uu.seUppsala University Publications
Change search
Refine search result
1 - 45 of 45
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1.
    Barnett, Paul D
    et al.
    University of Adelaide.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    O'Carroll, David C
    University of Adelaide .
    Motion adaptation and the velocity coding of natural scenes2010In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 20, no 11, p. 994-999Article in journal (Refereed)
    Abstract [en]

    Estimating relative velocity in the natural environment is challenging because natural scenes vary greatly in contrast and spatial structure. Widely accepted correlation-based models for elementary motion detectors (EMDs) are sensitive to contrast and spatial structure and consequently generate ambiguous estimates of velocity [1]. Identified neurons in the third optic lobe of the hoverfly can reliably encode the velocity of natural images largely independent of contrast [2], despite receiving inputs directly from arrays of such EMDs [3, 4]. This contrast invariance suggests an important role for additional neural processes in robust encoding of image motion [2, 5, 6]. However, it remains unclear which neural processes are contributing to contrast invariance. By recording from horizontal system neurons in the hoverfly lobula, we show two activity-dependent adaptation mechanisms acting as near-ideal normalizers for images of different contrasts that would otherwise produce highly variable response magnitudes. Responses to images that are initially weak neural drivers are boosted over several hundred milliseconds. Responses to images that are initially strong neural drivers are reduced over longer time scales. These adaptation mechanisms appear to be matched to higher-order natural image statistics reconciling the neurons' accurate encoding of image velocity with the inherent ambiguity of correlation-based motion detectors.

  • 2.
    Barnett, Paul
    et al.
    The University of Adelaide.
    Nordström, Karin
    O'Carroll, David
    The University of Adelaide.
    Retinotopic organization of small-field-target-detecting neurons in the insect visual system.2007In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 17, no 7, p. 569-578Article in journal (Refereed)
    Abstract [en]

    Background

    Despite having tiny brains and relatively low-resolution compound eyes, many fly species frequently engage in precisely controlled aerobatic pursuits of conspecifics. Recent investigations into high-order processing in the fly visual system have revealed a class of neurons, coined small-target-motion detectors (STMDs), capable of responding robustly to target motion against the motion of background clutter. Despite limited spatial acuity in the insect eye, these neurons display exquisite sensitivity to small targets.

     

    Results

    We recorded intracellularly from morphologically identified columnar neurons in the lobula complex of the hoverfly Eristalis tenax. We show that these columnar neurons with exquisitely small receptive fields, like their large-field counterparts recently described from both male and female flies, have an extreme selectivity for the motion of small targets. In doing so, we provide the first physiological characterization of small-field neurons in female flies. These retinotopically organized columnar neurons include both direction-selective and nondirection-selective classes covering a large area of visual space.

     

    Conclusions

    The retinotopic arrangement of lobula columnar neurons sensitive to the motion of small targets makes a strong case for these neurons as important precursors in the local processing of target motion. Furthermore, the continued response of STMDs with such small receptive fields to the motion of small targets in the presence of moving background clutter places further constraints on the potential mechanisms underlying their small-target tuning.

  • 3.
    Bolzon, Douglas M
    et al.
    University of Adelaide.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    O'Carroll, David C
    Local and large-range inhibition in feature detection2009In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 29, no 45, p. 14143-14150Article in journal (Refereed)
    Abstract [en]

    Lateral inhibition is perhaps the most ubiquitous of neuronal mechanisms, having been demonstrated in early stages of processing in many different sensory pathways of both mammals and invertebrates. Recent work challenges the long-standing view that assumes that similar mechanisms operate to tune neuronal responses to higher order properties. Scant evidence for lateral inhibition exists beyond the level of the most peripheral stages of visual processing, leading to suggestions that many features of the tuning of higher order visual neurons can be accounted for by the receptive field and other intrinsic coding properties of visual neurons. Using insect target neurons as a model, we present unequivocal evidence that feature tuning is shaped not by intrinsic properties but by potent spatial lateral inhibition operating well beyond the first stages of visual processing. In addition, we present evidence for a second form of higher-order spatial inhibition--a long-range interocular transfer of information that we argue serves a role in establishing interocular rivalry and thus potentially a neural substrate for directing attention to single targets in the presence of distracters. In so doing, we demonstrate not just one, but two levels of spatial inhibition acting beyond the level of peripheral processing.

  • 4. Brinkworth, Russel
    et al.
    McCann, Ben
    Matthews, Carol
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    First year expectations and experiences: Student and teacher perspectives 2009In: Higher Education, ISSN 0018-1560, E-ISSN 1573-174X, Vol. 58, no 2, p. 157-173Article in journal (Refereed)
    Abstract [en]

    Transitioning from high-school to university can be difficult, and many university teachers feel students are often ill-prepared for the change. To investigate this 233 Humanities and Science students at the University of Adelaide were surveyed 6 months into their first year regarding experiences of teaching and learning at university. 189 students were also surveyed 18 months after commencement, to gain retrospective views of their transition year, as were lecturers and tutors of both groups. Results were compared to similar Orientation Week questionnaires that focused on expectations. Questions included reasons for selecting degrees, quality of teacher feedback and perceived impact of outside commitments. Even though student expectations, student experience, and teacher views differed, remarkable similarities emerged across the two degree programs (Science and Humanities). Our findings thus highlight a call for non-specialised transition programs to meet the needs of first year students and facilitate the transition from secondary to tertiary education.

  • 5.
    de Haan, Roel
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Lee, Yu-Jen
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Novel Flicker-Sensitive Visual Circuit Neurons Inhibited by Stationary Patterns2013In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 33, no 21, p. 8980-8989Article in journal (Refereed)
    Abstract [en]

    Many animals use visual motion cues for navigating within their surroundings. Both flies and vertebrates compute local motion by temporal correlation of neighboring photoreceptors, via so-called elementary motion detectors (EMDs). In the fly lobula plate and the vertebrate visual cortex the output from many EMDs is pooled in neurons sensitive to wide-field optic flow. Although the EMD has been the preferred model for more than 50 years, recent work has highlighted its limitations in describing some visual behaviors, such as responses to higher-order motion stimuli. Non-EMD motion processing may therefore serve an important function in vision. Here, we describe a novel neuron class in the fly lobula plate that clearly does not derive its input from classic EMDs. The centrifugal stationary inhibited flicker excited (cSIFE) neuron is strongly excited by flicker, up to very high temporal frequencies. The non-EMD driven flicker sensitivity leads to strong, nondirectional responses to high-speed, wide-field motion. Furthermore, cSIFE is strongly inhibited by stationary patterns, within a narrow wavelength band. cSIFE's outputs overlap with the inputs of well described optic flow-sensitive lobula plate tangential cells (LPTCs). Driving cSIFE affects the active dendrites of LPTCs, and cSIFE may therefore play a large role in motion vision.

  • 6.
    de Haan, Roel
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Lee, Yu-Jen
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Octopaminergic modulation of contrast sensitivity2012In: Frontiers in Integrative Neuroscience, ISSN 1662-5145, E-ISSN 1662-5145, Vol. 6, no Article 55Article in journal (Refereed)
    Abstract [en]

    Sensory systems adapt to prolonged stimulation by decreasing their response to continuous stimuli. Whereas visual motion adaptation has traditionally been studied in immobilized animals, recent work indicates that the animal's behavioral state influences the response properties of higher-order motion vision-sensitive neurons. During insect flight octopamine is released, and pharmacological octopaminergic activation can induce a fictive locomotor state. In the insect optic ganglia, lobula plate tangential cells (LPTCs) spatially pool input from local elementary motion detectors (EMDs) that correlate luminosity changes from two spatially discrete inputs after delaying the signal from one. The LPTC velocity optimum thereby depends on the spatial separation of the inputs and on the EMD's delay properties. Recently it was shown that behavioral activity increases the LPTC velocity optimum, with modeling suggesting this to originate in the EMD's temporal delay filters. However, behavior induces an additional post-EMD effect: the LPTC membrane conductance increases in flying flies. To physiologically investigate the degree to which activity causes presynaptic and postsynaptic effects, we conducted intracellular recordings of Eristalis horizontal system (HS) neurons. We constructed contrast response functions before and after adaptation at different temporal frequencies, with and without the octopamine receptor agonist chlordimeform (CDM). We extracted three motion adaptation components, where two are likely to be generated presynaptically of the LPTCs, and one within them. We found that CDM affected the early, EMD-associated contrast gain reduction, temporal frequency dependently. However, a CDM-induced change of the HS membrane conductance disappeared during and after visual stimulation. This suggests that physical activity mainly affects motion adaptation presynaptically of LPTCs, whereas post-EMD effects have a minimal effect.

  • 7.
    Dyakova, Olga
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Lee, Yu-Jen
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Longden, Kit D.
    Kiselev, Valerij G.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    A higher order visual neuron tuned to the spatial amplitude spectra of natural scenes2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, article id 8522Article in journal (Refereed)
    Abstract [en]

    Animal sensory systems are optimally adapted to those features typically encountered in natural surrounds, thus allowing neurons with limited bandwidth to encode challengingly large input ranges. Natural scenes are not random, and peripheral visual systems in vertebrates and insects have evolved to respond efficiently to their typical spatial statistics. The mammalian visual cortex is also tuned to natural spatial statistics, but less is known about coding in higher order neurons in insects. To redress this we here record intracellularly from a higher order visual neuron in the hoverfly. We show that the cSIFE neuron, which is inhibited by stationary images, is maximally inhibited when the slope constant of the amplitude spectrum is close to the mean in natural scenes. The behavioural optomotor response is also strongest to images with naturalistic image statistics. Our results thus reveal a close coupling between the inherent statistics of natural scenes and higher order visual processing in insects.

  • 8.
    Dyakova, Olga
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Müller, Martin M
    Egelhaaf, Martin
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Image statistics of the environment surrounding freely behaving hoverflies2019In: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology, ISSN 0340-7594, E-ISSN 1432-1351, Vol. 205, no 3, p. 373-385Article in journal (Refereed)
    Abstract [en]

    Natural scenes are not as random as they might appear, but are constrained in both space and time. The 2-dimensional spatial constraints can be described by quantifying the image statistics of photographs. Human observers perceive images with naturalistic image statistics as more pleasant to view, and both fly and vertebrate peripheral and higher order visual neurons are tuned to naturalistic image statistics. However, for a given animal, what is natural differs depending on the behavior, and even if we have a broad understanding of image statistics, we know less about the scenes relevant for particular behaviors. To mitigate this, we here investigate the image statistics surrounding Episyrphus balteatus hoverflies, where the males hover in sun shafts created by surrounding trees, producing a rich and dense background texture and also intricate shadow patterns on the ground. We quantified the image statistics of photographs of the ground and the surrounding panorama, as the ventral and lateral visual field is particularly important for visual flight control, and found differences in spatial statistics in photos where the hoverflies were hovering compared to where they were flying. Our results can, in the future, be used to create more naturalistic stimuli for experimenter-controlled experiments in the laboratory.

  • 9.
    Dyakova, Olga
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology. Centre for Neuroscience, Flinders University, Adelaide, Australia.
    Image statistics and their processing in insect vision2017In: Current Opinion in Insect Science, ISSN 2214-5745, Vol. 24, p. 7-14Article, review/survey (Refereed)
    Abstract [en]

    Natural scenes may appear random, but are not only constrained in space and time, but also show strong spatial and temporal correlations. Spatial constraints and correlations can be described by quantifying image statistics, which include intuitive measures such as contrast, color and luminance, but also parameters that need some type of transformation of the image. In this review we will discuss some common tools used to quantify spatial and temporal parameters of naturalistic visual input, and how these tools have been used to inform us about visual processing in insects. In particular, we will review findings that would not have been possible using conventional, experimenter defined stimuli.

  • 10.
    Dyakova, Olga
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Nordström: Motion Vision.
    Rångtell, Frida H
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Schiöth: Functional Pharmacology.
    Tan, Xiao
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Schiöth: Functional Pharmacology.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Nordström: Motion Vision. Centre for Neuroscience, Flinders University, Adelaide, South Australia, Australia.
    Benedict, Christian
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Schiöth: Functional Pharmacology.
    Acute sleep loss induces signs of visual discomfort in young men2019In: Journal of Sleep Research, ISSN 0962-1105, E-ISSN 1365-2869, Vol. 28, no 6, article id e12837Article in journal (Refereed)
    Abstract [en]

    Acute sleep loss influences visual processes in humans, such as recognizing facial emotions. However, to the best of our knowledge, no study till date has examined whether acute sleep loss alters visual comfort when looking at images. One image statistic that can be used to investigate the level of visual comfort experienced under visual encoding is the slope of the amplitude spectrum, also referred to as the slope constant. The slope constant describes the spatial distribution of pixel intensities and deviations from the natural slope constant can induce visual discomfort. In the present counterbalanced crossover design study, 11 young men with normal or corrected-to-normal vision participated in two experimental conditions: one night of sleep loss and one night of sleep. In the morning after each intervention, subjects performed a computerized psychophysics task. Specifically, they were required to adjust the slope constant of images depicting natural landscapes and close-ups with a randomly chosen initial slope constant until they perceived each image as most natural looking. Subjects also rated the pleasantness of each selected image. Our analysis showed that following sleep loss, higher slope constants were perceived as most natural looking when viewing images of natural landscapes. Images with a higher slope constant are generally perceived as blurrier. The selected images were also rated as less pleasant after sleep loss. No such differences between the experimental conditions were noted for images of close-ups. The results suggest that sleep loss induces signs of visual discomfort in young men. Possible implications of these findings are discussed.

  • 11.
    Geurten, Bart
    et al.
    The University of Adelaide.
    Nordström, Karin
    Sprayberry, Jordanna
    The University of Adelaide.
    Bolzon, Douglas
    The University of Adelaide.
    O, David
    The University of Adelaide.
    Neural mechanisms underlying target detection in a dragonfly centrifugal neuron.2007In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 210, no 18, p. 3277-3284Article in journal (Refereed)
    Abstract [en]

    Visual identification of targets is an important task for many animals searching for prey or conspecifics. Dragonflies utilize specialized optics in the dorsal acute zone, accompanied by higher-order visual neurons in the lobula complex, and descending neural pathways tuned to the motion of small targets. While recent studies describe the physiology of insect small target motion detector (STMD) neurons, little is known about the mechanisms that underlie their exquisite sensitivity to target motion. Lobula plate tangential cells (LPTCs), a group of neurons in dipteran flies selective for wide-field motion, have been shown to take input from local motion detectors consistent with the classic correlation model developed by Hassenstein and Reichardt in the 1950s. We have tested the hypothesis that similar mechanisms underlie the response of dragonfly STMDs. We show that an anatomically characterized centrifugal STMD neuron (CSTMD1) gives responses that depend strongly on target contrast, a clear prediction of the correlation model. Target stimuli are more complex in spatiotemporal terms than the sinusoidal grating patterns used to study LPTCs, so we used a correlation-based computer model to predict response tuning to velocity and width of moving targets. We show that increasing target width in the direction of travel causes a shift in response tuning to higher velocities, consistent with our model. Finally, we show how the morphology of CSTMD1 allows for impressive spatial interactions when more than one target is present in the visual field.

  • 12. Gonzalez-Bellido, Paloma T
    et al.
    Fabian, Samuel T
    Nordström, Karin
    Centre for Neuroscience, Flinders University, GPO Box 2100, Adelaide, SA 5001, Australia.
    Target detection in insects: optical, neural and behavioral optimizations2016In: Current Opinion in Neurobiology, ISSN 0959-4388, E-ISSN 1873-6882, Vol. 41, p. 122-128Article in journal (Refereed)
    Abstract [en]

    Motion vision provides important cues for many tasks. Flying insects, for example, may pursue small, fast moving targets for mating or feeding purposes, even when these are detected against self-generated optic flow. Since insects are small, with size-constrained eyes and brains, they have evolved to optimize their optical, neural and behavioral target visualization solutions. Indeed, even if evolutionarily distant insects display different pursuit strategies, target neuron physiology is strikingly similar. Furthermore, the coarse spatial resolution of the insect compound eye might actually be beneficial when it comes to detection of moving targets. In conclusion, tiny insects show higher than expected performance in target visualization tasks.

  • 13.
    Hidayat, Egi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Medvedev, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Identification of the elementary motion detector model in fly motion vision from intracellularly recorded neural data2014Article in journal (Other academic)
  • 14.
    Hidayat, Egi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Medvedev, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Identification of the Reichardt elementary motion detector model2015In: Signal and Image Analysis for Biomedical and Life Sciences, Springer, 2015, p. 83-105Chapter in book (Refereed)
    Abstract [en]

    The classical Hassenstein-Reichardt mathematical elementary motion detector (EMD) model is treated analytically. The EMD is stimulated with drifting sinusoidal gratings, which are often used in motion vision research, thus enabling direct comparison with neural responses from motion-sensitive neurones in the fly brain. When sinusoidal gratings are displayed on a cathode ray tube monitor, they are modulated by the refresh rate of the monitor. This generates a pulsatile signature of the visual stimulus, which is also seen in the neural response. Such pulsatile signals make a Laguerre domain identification method for estimating the parameters of a single EMD suitable, allowing estimation of both finite and infinite-dimensional dynamics. To model the response of motion-sensitive neurones with large receptive fields, a pool of spatially distributed EMDs is considered, with the weights of the contributing EMDs fitted to the neural data by a sparse estimation method. Such an EMD-array is more reliably estimated by stimulating with multiple sinusoidal gratings, since these provide higher spatial excitation than a single sinusoidal grating. Consequently, a way of designing the visual stimuli for a certain order of spatial resolution is suggested.

  • 15.
    Hidayat, Egi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Medvedev, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Laguerre Domain Identification of the Elementary Motion Detector Model in Insect Vision2013In: Adaptation and Learning in Control and Signal Processing, International Federation of Automatic Control , 2013, p. 623-628Conference paper (Refereed)
    Abstract [en]

    A Laguerre domain approach to the identification of the so-called Elementary Motion Detector (EMD) that is hypothesized to constitute the basis of biological motion vision in nearly all animals is proposed. Despite the vast popularity of the EMD concept in both biology and biologically inspired computer vision, the problem of estimating the dynamics of the EMD from experimental data has been poorly addressed. The choice of the Laguerre domain for the representation of the input and the output of the EMD is motivated by the pulse-modulated character of the visual stimuli produced by the CRT displays that are often used in animal experiments. An analytical expression for the Laguerre spectrum of the EMD output given the Laguerre spectrum of the input is derived and a parameter estimation algorithm of the system dynamics is developed. The feasibility of the approach is illustrated by simulation using actual visual stimuli from fly electrophysiology.

  • 16.
    Hidayat, Egi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Medvedev, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    On identification of elementary motion detectors2013In: Computational Models for Life Sciences: CMLS 2013, Melville, NY: American Institute of Physics (AIP), 2013, p. 14-23Conference paper (Refereed)
    Abstract [en]

    The classical mathematical elementary motion detector (EMD) model stimulated with sinusoidal and pulsatile input signals is treated analytically. Drifting sinusoidal gratings are often used in insect vision research, enabling direct comparison with biological data. When displayed on a cathode ray tube monitor, the sinusoidal grating is modulated by the refresh rate of the monitor. Due to the resulting pulsatile nature of the visual stimuli and the corresponding biological response, a Laguerre domain identification method for estimating the dynamics of a single EMD appears to be suitable. A pool of spatially distributed EMDs is considered as the model for the measured neural output. The weights of the contributing EMDs are evaluated by a sparse optimization method to fit the experimental data.

  • 17.
    Hidayat, Egi
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Soltanalian, Mojtaba
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Medvedev, Alexander
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Systems and Control. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Automatic control.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Spatial excitation properties of sinusoidal grating stimuli in the identification of a layer of motion detectors2014Article in journal (Other academic)
  • 18. Huss, Mikael
    et al.
    Nordström, Karin
    Prediction of transcription factor binding to DNA using rule induction methods2006In: Journal of Integrative Bioinformatics - JIB, ISSN 1613-4516, Vol. 3, no 2, p. 42-Article in journal (Refereed)
    Abstract [en]

    In this study, we seek to develop a predictive model for finding the strength of bindingbetween a particular transcription factor (TF) variant and a particular DNA target variant.The DNA binding paired domains of the Pax transcription factors, which are our mainfocus, show seemingly fuzzy and degenerate binding to various DNA targets, and paireddomain-DNA binding is not a problem well suited for previously proposed algorithms.Here, we introduce a simple way to use rule induction for predicting the strength of TFDNAbinding. We have created a dataset consisting of 597 example cases for paireddomain-DNA binding by collecting information about all published and quantifiedinteractions between TF and DNA sequence variants. Application of the rule inductionbased method on this dataset yields a high, although far from ideal accuracy of 69.7%(based on cross-validation), but perhaps more importantly, several useful rules forpredicting the binding strength have been found. Although the primary motivation forintroducing the rule induction based methods is the lack of efficient algorithms for paireddomain-DNA binding prediction, we also show that the method can be applied with somesuccess to a more well-studied TF-DNA binding prediction task involving the earlygrowth response (EGR) TF family.

  • 19.
    Larhammar, Dan
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Pharmacology.
    Nordström, Karin
    School of Molecular and Biomedical Science, The University of Adelaide, Adelaide SA 5005, Australia .
    Larsson, Tomas A.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Pharmacology.
    Evolution of vertebrate rod and cone phototransduction genes2009In: Philosophical Transactions of the Royal Society of London. Biological Sciences, ISSN 0962-8436, E-ISSN 1471-2970, Vol. 364, no 1531, p. 2867-2880Article, review/survey (Refereed)
    Abstract [en]

    Vertebrate cones and rods in several cases use separate but related components for their signal transduction (opsins, G-proteins, ion channels, etc.). Some of these proteins are also used differentially in other cell types in the retina. Because cones, rods and other retinal cell types originated in early vertebrate evolution, it is of interest to see if their specific genes arose in the extensive gene duplications that took place in the ancestor of the jawed vertebrates (gnathostomes) by two tetraploidizations (genome doublings). The ancestor of teleost fishes subsequently underwent a third tetraploidization. Our previously reported analyses showed that several gene families in the vertebrate visual phototransduction cascade received new members in the basal tetraploidizations. We here expand these data with studies of additional gene families and vertebrate species. We conclude that no less than 10 of the 13 studied phototransduction gene families received additional members in the two basal vertebrate tetraploidizations. Also the remaining three families seem to have undergone duplications during the same time period but it is unclear if this happened as a result of the tetraploidizations. The implications of the many early vertebrate gene duplications for functional specialization of specific retinal cell types, particularly cones and rods, are discussed.

  • 20.
    Lee, Yu-Jen
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Jönsson, Olof H.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Spatio-temporal dynamics of impulse responses to figure motion in optic flow neurons2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 5, article id e0126265Article in journal (Refereed)
    Abstract [en]

    White noise techniques have been used widely to investigate sensory systems in both vertebrates and invertebrates. White noise stimuli are powerful in their ability to rapidly generate data that help the experimenter decipher the spatio-temporal dynamics of neural and behavioral responses. One type of white noise stimuli, maximal length shift register sequences (m-sequences), have recently become particularly popular for extracting response kernels in insect motion vision. We here use such m-sequences to extract the impulse responses to figure motion in hoverfly lobula plate tangential cells (LPTCs). Figure motion is behaviorally important and many visually guided animals orient towards salient features in the surround. We show that LPTCs respond robustly to figure motion in the receptive field. The impulse response is scaled down in amplitude when the figure size is reduced, but its time course remains unaltered. However, a low contrast stimulus generates a slower response with a significantly longer time-to-peak and half-width. Impulse responses in females have a slower time-to-peak than males, but are otherwise similar. Finally we show that the shapes of the impulse response to a figure and a widefield stimulus are very similar, suggesting that the figure response could be coded by the same input as the widefield response.

  • 21.
    Lee, Yu-Jen
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Higher-order motion sensitivity in fly visual circuits2012In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 109, no 22, p. 8758-8763Article in journal (Refereed)
    Abstract [en]

    In higher-order motion stimuli, the direction of object motion does not follow the direction of luminance change. Such stimuli could be generated by the wing movements of a flying butterfly and further complicated by its motion in and out of shadows. Human subjects readily perceive the direction of higher-order motion, although this stands in stark contrast to prevailing motion vision models. Flies and humans compute motion in similar ways, and because flies behaviorally track bars containing higher-order motion cues, they become an attractive model system for investigating the neurophysiology underlying higher-order motion sensitivity. We here use intracellular electrophysiology of motion-vision-sensitive neurons in the hoverfly lobula plate to quantify responses to stimuli containing higher-order motion. We show that motion sensitivity can be broken down into two separate streams, directionally coding for elementary motion and figure motion, respectively, and that responses to Fourier and theta motion can be predicted from these. The sensitivity is affected both by the stimulus' time course and by the neuron's underlying receptive field. Responses to preferred-direction theta motion are sexually dimorphic and particularly robust along the visual midline.

  • 22.
    Nicholas, Sarah
    et al.
    Centre for Neuroscience, Flinders University, 5001 Adelaide, South Australia, Australia.
    Supple, Jack
    Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, United Kingdom.
    Leibbrandt, Richard
    Centre for Neuroscience, Flinders University, 5001 Adelaide, South Australia, Australia.
    Gonzalez-Bellido, Paloma T
    Department of Ecology, Evolution, and Behavior, University of Minnesota, St. Paul, Minnesota, USA; Department of Physiology, Development and Neuroscience, University of Cambridge, Cambridge CB2 3EG, United Kingdom.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Integration of Small- and Wide-Field Visual Features in Target-Selective Descending Neurons of both Predatory and Non-Predatory Dipterans2018In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 38, no 50, p. 10725-10733Article in journal (Refereed)
    Abstract [en]

    For many animals, target motion carries high ecological significance as this may be generated by a predator, prey or potential mate. Indeed, animals whose survival depends on early target detection are often equipped with a sharply tuned visual system, yielding robust performance in challenging conditions. For example, many fast-flying insects use visual cues for identifying targets, such as prey (e.g. predatory dragonflies and robberflies) or conspecifics (e.g. non-predatory hoverflies), and can often do so against self-generated background optic flow. Supporting these behaviors, the optic lobes of insects that pursue targets harbor neurons that respond robustly to the motion of small moving objects, even when displayed against syn-directional background clutter. However, in diptera, the encoding of target information by the descending neurons, which are more directly involved in generating the behavioral output, has received less attention. We characterized target selective neurons by recording in the ventral nerve cord of male and female predatory Holcocephala fusca robberflies and of male non-predatory Eristalis tenax hoverflies. We show that both species have dipteran target-selective descending neurons (dTSDNs) that only respond to target motion if the background is stationary or moving slowly, moves in the opposite direction, or has un-naturalistic spatial characteristics. The response to the target is suppressed when background and target move at similar velocities, which is strikingly different to the response of target neurons in the optic lobes. As the neurons we recorded from are pre-motor, our findings affect our interpretation of the neurophysiology underlying target-tracking behaviors.SIGNIFICANCE STATEMENTMany animals use sensory cues to detect moving targets that may represent predators, prey or conspecifics. For example, birds of prey show superb sensitivity to the motion of small prey, and intercept these at high speeds. In a similar manner, predatory insects visually track moving prey, often against cluttered backgrounds. Accompanying this behavior, the brains of insects that pursue targets contain neurons that respond exclusively to target motion. We here show that dipteran insects also have target selective descending neurons in the part of their nervous system that corresponds to the vertebrate spinal cord. Surprisingly, and in contrast to the neurons in the brain, these pre-motor neurons are inhibited by background patterns moving in the same direction as the target.

  • 23. Nicholas, Sarah
    et al.
    Thyselius, Malin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Holden, Marissa
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Rearing and Long-Term Maintenance of Eristalis tenax Hoverflies for Research Studies.2018In: Journal of Visualized Experiments, ISSN 1940-087X, E-ISSN 1940-087X, no 135, article id e57711Article in journal (Refereed)
    Abstract [en]

    With an estimated 6000 species worldwide, hoverflies are ecologically important as alternative pollinators to domesticated honeybees. However, they are also a useful scientific model to study motion vision and flight dynamics in a controlled laboratory setting. As the larvae develop in organically polluted water, they are useful models for investigating investment in microbial immunity. While large scale commercial breeding for agriculture already occurs, there are no standardized protocols for maintaining captive populations for scientific studies. This is important as commercial captive breeding programs focusing on mass output during peak pollination periods may fail to provide a population that is consistent, stable and robust throughout the year, as is often needed for other research purposes. Therefore, a method to establish, maintain and refresh a captive research population is required. Here, we describe the utilization of an artificial hibernation cycle, in addition to the nutritional and housing requirements, for long term maintenance of Eristalis tenax. Using these methods, we have significantly increased the health and longevity of captive populations of E. tenax compared to previous reports. We furthermore discuss small scale rearing methods and options for optimizing yields and manipulating population demographics.

  • 24.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Neural specializations for small target detection in insects2012In: Current Opinion in Neurobiology, ISSN 0959-4388, E-ISSN 1873-6882, Vol. 22, no 2, p. 272-278Article in journal (Refereed)
    Abstract [en]

    Despite being equipped with low-resolution eyes and tiny brains, many insects show exquisite abilities to detect and pursue targets even in highly textured surrounds. Target tracking behavior is subserved by neurons that are sharply tuned to the motion of small high-contrast targets. These neurons respond robustly to target motion, even against self-generated optic flow. A recent model, supported by neurophysiology, generates target selectivity by being sharply tuned to the unique spatiotemporal profile associated with target motion. Target neurons are likely connected in a complex network where some provide more direct output to behavior, whereas others serve an inter-regulatory role. These interactions may regulate attention and aid in the robust detection of targets in clutter observed in behavior.

  • 25.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Robust prey detection in a small nervous system2013In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 110, no 2, p. 389-390Article in journal (Other (popular science, discussion, etc.))
  • 26.
    Nordström, Karin
    et al.
    The University of Adelaide.
    Barnett, Paul D
    The University of Adelaide.
    O'Carroll, David C
    The University of Adelaide.
    Insect detection of small targets moving in visual clutter.2006In: PLoS biology, ISSN 1544-9173, E-ISSN 1545-7885, Vol. 4, no 3, p. e54-Article in journal (Refereed)
    Abstract [en]

    Detection of targets that move within visual clutter is a common task for animals searching for prey or conspecifics, a task made even more difficult when a moving pursuer needs to analyze targets against the motion of background texture (clutter). Despite the limited optical acuity of the compound eye of insects, this challenging task seems to have been solved by their tiny visual system. Here we describe neurons found in the male hoverfly, Eristalis tenax, that respond selectively to small moving targets. Although many of these target neurons are inhibited by the motion of a background pattern, others respond to target motion within the receptive field under a surprisingly large range of background motion stimuli. Some neurons respond whether or not there is a speed differential between target and background. Analysis of responses to very small targets (smaller than the size of the visual field of single photoreceptors) or those targets with reduced contrast shows that these neurons have extraordinarily high contrast sensitivity. Our data suggest that rejection of background motion may result from extreme selectivity for small targets contrasting against local patches of the background, combined with this high sensitivity, such that background patterns rarely contain features that satisfactorily drive the neuron.

  • 27. Nordström, Karin
    et al.
    Barnett, Paul
    The University of Adelaide.
    Moyer de Miguel, Irene
    The University of Adelaide.
    Brinkworth, Russel
    The University of Adelaide.
    O'Carroll, David
    The University of Adelaide.
    Sexual dimorphism in the hoverfly motion vision pathway.2008In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 18, no 9, p. 661-667Article in journal (Refereed)
    Abstract [en]

    Many insects perform high-speed aerial maneuvers in which they navigate through visually complex surrounds. Among insects, hoverflies stand out, with males switching from stationary hovering to high-speed pursuit at extreme angular velocities [1]. In dipterans, 50-60 large interneurons -- the lobula-plate tangential cells (LPTCs) -- detect changes in optic flow experienced during flight [2-5]. It has been predicted that large LPTC receptive fields are a requirement of accurate "matched filters" of optic flow [6]. Whereas many fly taxa have three horizontal system (HS) LPTC neurons in each hemisphere, hoverflies have four [7], possibly reflecting the more sophisticated flight behavior. We here show that the most dorsal hoverfly neuron (HS north [HSN]) is sexually dimorphic, with the male receptive field substantially smaller than in females or in either sex of blowflies. The (hoverfly-specific) HSN equatorial (HSNE) is, however, sexually isomorphic. Using complex optic flow, we show that HSN, despite its smaller receptive field, codes yaw velocity as well as HSNE. Responses to a target moving against a plain or textured background suggest that the male HSN could potentially play a role in target pursuit under some conditions.

  • 28.
    Nordström, Karin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Bolzon, Douglas M.
    O'Carroll, David C.
    Spatial facilitation by a high-performance dragonfly target-detecting neuron2011In: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 7, no 4, p. 588-592Article in journal (Refereed)
    Abstract [en]

    Many animals visualize and track small moving targets at long distances-be they prey, approaching predators or conspecifics. Insects are an excellent model system for investigating the neural mechanisms that have evolved for this challenging task. Specialized small target motion detector (STMD) neurons in the optic lobes of the insect brain respond strongly even when the target size is below the resolution limit of the eye. Many STMDs also respond robustly to small targets against complex stationary or moving backgrounds. We hypothesized that this requires a complex mechanism to avoid breakthrough responses by background features, and yet to adequately amplify the weak signal of tiny targets. We compared responses of dragonfly STMD neurons to small targets that begin moving within the receptive field with responses to targets that approach the same location along longer trajectories. We find that responses along longer trajectories are strongly facilitated by a mechanism that builds up slowly over several hundred milliseconds. This allows the neurons to give sustained responses to continuous target motion, thus providing a possible explanation for their extraordinary sensitivity.

  • 29.
    Nordström, Karin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology. Flinders University, Centre for Neuroscience, Adelaide.
    Dahlbom, Josefin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Pragadheesh, V.S.
    Tata Institute of Fundamental Research, National Centre for Biological Sciences, Naturalist-Inspired Chemical Ecology, Bangalore.
    Ghosh, Suhrid
    Tata Institute of Fundamental Research, National Centre for Biological Sciences, Naturalist-Inspired Chemical Ecology, Bangalore; Max Planck Institute of Molecular Cell Biology and Genetics, Suzanne Eaton Group, Dresden.
    Olsson, Amadeus
    Tata Institute of Fundamental Research, National Centre for Biological Sciences, Naturalist-Inspired Chemical Ecology, Bangalore.
    Dyakova, Olga
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Krishna Suresh, Shravanti
    Tata Institute of Fundamental Research, National Centre for Biological Sciences, Naturalist-Inspired Chemical Ecology, Bangalore; Iowa State University, College of Liberal Arts and Sciences, Ames.
    Olsson, Shannon B.
    Tata Institute of Fundamental Research, National Centre for Biological Sciences, Naturalist-Inspired Chemical Ecology, Bangalore.
    In situ modeling of multimodal floral cues attracting wild pollinators across environments2017In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 114, no 50, p. 13218-13223Article in journal (Refereed)
    Abstract [en]

    With more than 80% of flowering plant species specialized for animal pollination, understanding how wild pollinators utilize resources across environments can encourage efficient planting and maintenance strategies to maximize pollination and establish resilience in the face of environmental change. A fundamental question is how generalist pollinators recognize “flower objects” in vastly different ecologies and environments. On one hand, pollinators could employ a specific set of floral cues regardless of environment. Alternatively, wild pollinators could recognize an exclusive signature of cues unique to each environment or flower species. Hoverflies, which are found across the globe, are one of the most ecologically important alternative pollinators after bees and bumblebees. Here, we have exploited their cosmopolitan status to understand how wild pollinator preferences change across different continents. Without employing any a priori assumptions concerning the floral cues, we measured, predicted, and finally artificially recreated multimodal cues from individual flowers visited by hoverflies in three different environments (hemiboreal, alpine, and tropical) using a field-based methodology. We found that although “flower signatures” were unique for each environment, some multimodal lures were ubiquitously attractive, despite not carrying any reward, or resembling real flowers. While it was unexpected that cue combinations found in real flowers were not necessary, the robustness of our lures across insect species and ecologies could reflect a general strategy of resource identification for generalist pollinators. Our results provide insights into how cosmopolitan pollinators such as hoverflies identify flowers and offer specific ecologically based cues and strategies for attracting pollinators across diverse environments.

  • 30.
    Nordström, Karin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    de Miguel, Irene Moyer
    O'Carroll, David C.
    Rapid contrast gain reduction following motion adaptation2011In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 214, no 23, p. 4000-4009Article in journal (Refereed)
    Abstract [en]

    Neural and sensory systems adapt to prolonged stimulation to allow signaling across broader input ranges than otherwise possible with the limited bandwidth of single neurons and receptors. In the visual system, adaptation takes place at every stage of processing, from the photoreceptors that adapt to prevailing luminance conditions, to higher-order motion-sensitive neurons that adapt to prolonged exposure to motion. Recent experiments using dynamic, fluctuating visual stimuli indicate that adaptation operates on a time scale similar to that of the response itself. Further work from our own laboratory has highlighted the role for rapid motion adaptation in reliable encoding of natural image motion. Physiologically, motion adaptation can be broken down into four separate components. It is not clear from the previous studies which of these motion adaptation components are involved in the fast and dynamic response changes. To investigate the adapted response in more detail, we therefore analyzed the effect of motion adaptation using a test-adapt-test protocol with adapting durations ranging from 20 ms to 20 s. Our results underscore the very rapid rate of motion adaptation, suggesting that under free flight, visual motion-sensitive neurons continuously adapt to the changing scenery. This might help explain recent observations of strong invariance in the response to natural scenes with highly variable contrast and image structure.

  • 31.
    Nordström, Karin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Gonzalez-Bellido, Paloma T.
    MBL.
    Invertebrate vision: Peripheral adaptation to repeated object motion2013In: Current Biology, ISSN 0960-9822, E-ISSN 1879-0445, Vol. 23, no 15, p. R655-R656Article in journal (Other academic)
    Abstract [en]

    Visual systems adapt rapidly to objects moving repeatedly within the visual field, because such objects are likely irrelevant. In the crab, the neural switch for such adaptation has been found to take place at a surprisingly early stage of the visual processing pathway.

  • 32. Nordström, Karin
    et al.
    Larsson, Tomas A
    Larhammar, Dan
    Extensive duplications of phototransduction genes in early vertebrate evolution correlate with block (chromosome) duplications.2004In: Genomics, ISSN 0888-7543, E-ISSN 1089-8646, Vol. 83, no 5, p. 852-72Article in journal (Refereed)
    Abstract [en]

    Many gene families in mammals have members that are expressed more or less uniquely in the retina or differentially in specific retinal cell types. We describe here analyses of nine such gene families with regard to phylogenetic relationships and chromosomal location. The families are opsins, G proteins (alpha, beta, and gamma subunits), phosphodiesterases type 6, cyclic nucleotide-gated channels, G-protein-coupled receptor kinases, arrestins, and recoverins. The results suggest that multiple new gene copies arose in all of these families very early in vertebrate evolution during a period with extensive gene duplications. Many of the new genes arose through duplications of large chromosome regions (blocks of genes) or even entire chromosomes, as shown by linkage with other gene families. Some of the phototransduction families belong to the same duplicated regions and were thus duplicated simultaneously. We conclude that gene duplications in early vertebrate evolution probably helped facilitate the specialization of the retina and the subspecialization of different retinal cell types.

  • 33. Nordström, Karin
    et al.
    O'Carroll, David
    The University of Adelaide.
    Feature detection and the hypercomplex property in insects.2009In: TINS - Trends in Neurosciences, ISSN 0166-2236, E-ISSN 1878-108X, Vol. 32, no 7, p. 383-391Article in journal (Refereed)
    Abstract [en]

    Discerning a target amongst visual ‘clutter’ is a complicated task that has been elegantly solved by flying insects, as evidenced by their mid-air interactions with conspecifics and prey. The neurophysiology of smalltarget motion detectors (STMDs) underlying these complex behaviors has recently been described and suggests that insects use mechanisms similar to those of hypercomplex cells of the mammalian visual cortex to achieve target-specific tuning. Cortical hypercomplex cells are end-stopped, which means that they respond optimally to small moving targets, with responses to extended bars attenuated. We review not only the underlying mechanisms involved in this tuning but also how recently proposed models provide a possible explanation for another remarkable property of these neurons – their ability to respond robustly to the motion of targets even against moving backgrounds.

     

  • 34. Nordström, Karin
    et al.
    O'Carroll, David
    The University of Adelaide.
    The motion after-effect: local and global contributions to contrast sensitivity.2009In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 276, no 1662, p. 1545-1554Article in journal (Refereed)
    Abstract [en]

    Motion adaptation is a widespread phenomenon analogous to peripheral sensory adaptation, presumed to play a role in matching responses to prevailing current stimulus parameters and thus to maximize efficiency of motion coding. While several components of motion adaptation (contrast gain reduction, output range reduction and motion after-effect) have been described, previous work is inconclusive as to whether these are separable phenomena and whether they are locally generated. We used intracellular recordings from single horizontal system neurons in the fly to test the effect of local adaptation on the full contrast-response function for stimuli at an unadapted location. We show that contrast gain and output range reductions are primarily local phenomena and are probably associated with spatially distinct synaptic changes, while the antagonistic after-potential operates globally by transferring to previously unadapted locations. Using noise analysis and signal processing techniques to remove 'spikelets', we also characterize a previously undescribed alternating current component of adaptation that can explain several phenomena observed in earlier studies.

  • 35. Nordström, Karin
    et al.
    O'Carroll, David C
    Small object detection neurons in female hoverflies.2006In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 273, no 1591, p. 1211-6Article in journal (Refereed)
    Abstract [en]

    While predators such as dragonflies are dependent on visual detection of moving prey, social interactions make conspecific detection equally important for many non-predatory insects. Specialized 'acute zones' associated with target detection have evolved in several insect groups and are a prominent male-specific feature in many dipteran flies. The physiology of target selective neurons associated with these specialized eye regions has previously been described only from male flies. We show here that female hoverflies (Eristalis tenax) have several classes of neurons within the third optic ganglion (lobula) capable of detecting moving objects smaller than 1 degrees . These neurons have frontal receptive fields covering a large part of the ipsilateral world and are tuned to a broad range of target speeds and sizes. This could make them suitable for detecting targets under a range of natural conditions such as required during predator avoidance or conspecific interactions.

  • 36. Nordström, Karin
    et al.
    Scholten, Ingo
    Nordström, Johanna
    Larhammar, Dan
    Miller, David
    Mutational analysis of the Acropora millepora PaxD paired domain highlights the importance of the linker region for DNA binding.2003In: Gene, ISSN 0378-1119, E-ISSN 1879-0038, Vol. 320, p. 81-7Article in journal (Refereed)
    Abstract [en]

    Pax transcription factors are found in animals, from simple sponges to insects and vertebrates. The defining feature of Pax proteins is the DNA-binding paired domain (PD), which consists of two helix-turn-helix subdomains, joined with a linker region. Despite high specificity in vivo, the paired domains of different Pax proteins bind similar consensus DNA sequences in vitro. Using bandshift techniques, we show here that the paired domain of the Acropora millepora PaxD protein, which unambiguously belongs to the Pax3/7 group, does not bind to three defined paired domain-binding sites. Domain swapping experiments and site-directed mutagenesis identified two amino acid residues in the linker region of the paired domain as critical to DNA binding; G70 and S71 are highly conserved in Pax proteins, but differ in PaxD (L70 and N71). The PaxD data thus highlight the importance of the linker region, and particularly G70 and S71, in DNA binding by Pax proteins.

  • 37. Nordström, Karin
    et al.
    Wallén, Rita
    Seymour, Jamie
    Nilsson, Dan
    A simple visual system without neurons in jellyfish larvae.2003In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 270, no 1531, p. 2349-54Article in journal (Refereed)
    Abstract [en]

    Earlier detailed studies of cnidarian planula larvae have revealed a simple nervous system but no eyes or identifiable light sensing structures. Here, we describe the planula of a box jellyfish, Tripedalia cystophora, and report that these larvae have an extremely simple organization with no nervous system at all. Their only advanced feature is the presence of 10-15 pigment-cup ocelli, evenly spaced across the posterior half of the larval ectoderm. The ocelli are single cell structures containing a cup of screening pigment filled with presumably photosensory microvilli. These rhabdomeric photoreceptors have no neural connections to any other cells, but each has a well-developed motor-cilium, appearing to be the only means by which light can control the behaviour of the larva. The ocelli are thus self-contained sensory-motor entities, making a nervous system superfluous.

  • 38. O'Carroll, David
    et al.
    Barnett, Paul
    Mah, Eng
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Brinkworth, Russell
    A neuromorphic model for a robust, adaptive photoreceptor reduces variability in correlation based motion detectors2006In: Proc. Second. Int. ICSC Symposium Brain Inspired Cognitive Systems (BICS), 2006, p. 34-34Conference paper (Refereed)
  • 39. O'Carroll, David
    et al.
    Barnett, Paul
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Computational models reveal non-linearity in integration of local motion signals by insect motion detectors viewing natural scenes2011In: Proceedings of 7th International conference on Intelligent Sensors, Sensor Networks and Information Processing: ISSNIP 2011, 2011, p. 131-136Conference paper (Refereed)
    Abstract [en]

    Motion detection in animals and humans employs non-linear correlation of local spatiotemporal contrast induced by movement through the environment to estimate local motion. An undesirable consequence of this mechanism is that variability in pattern structure and contrast inherent in natural scenes profoundly influences local motion responses. In fly motion detection, this `pattern noise' is mitigated in part by spatial integration across wide regions of space to form matched filters for expected higher order patterns of optical flow. While this spatial averaging provides a partial solution to the pattern noise problem, recent work using physiological techniques highlights contributions to velocity coding from static non-linear spatial integration mechanisms (spatial gain control) and dynamic temporal gain control mechanisms. Little is known, however, about how such non-linearities co-ordinate to assist neural coding in the context of the motion of natural scenes. In this paper we used a simple computational model for an array of elaborated elementary motion detector (EMDs) based on the classical Hassenstein-Reichardt correlation model, as a predictor for the local pattern dependence of responses to a set of natural scenes as used in our recent work on velocity coding. Our results reveal that receptive field alone is a poor predictor of the spatial integration properties of these neurons. If anything, additional non-linearity appears to enhance the pattern dependence of the response.

  • 40. O'Carroll, David C.
    et al.
    Barnett, Paul D.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Local and global responses of insect motion detectors to the spatial structure of natural scenes2011In: Journal of Vision, ISSN 1534-7362, E-ISSN 1534-7362, Vol. 11, no 14, p. 20-Article in journal (Refereed)
    Abstract [en]

    As a consequence of the non-linear correlation mechanism underlying motion detection, the variability in local pattern structure and contrast inherent within natural scenes profoundly influences local motion responses. To accurately interpret optic flow induced by self-motion, neurons in many dipteran flies smooth this "pattern noise" by wide-field spatial integration. We investigated the role that size and shape of the receptive field plays in smoothing out pattern noise in two unusual hoverfly optic flow neurons: one (HSN) with an exceptionally small receptive field and one (HSNE) with a larger receptive field. We compared the local and global responses to a sequence of panoramic natural images in these two neurons with a parsimonious model for elementary motion detection weighted for their spatial receptive fields. Combined with manipulation of size and contrast of the stimulus images, this allowed us to separate spatial integration properties arising from the receptive field, from other local and global non-linearities, such as motion adaptation and dendritic gain control. We show that receptive field properties alone are poor predictors of the response to natural scenes. If anything, additional non-linearity enhances the pattern dependence of HSN's response, particularly to vertically elongated features, suggesting that it may serve a role in forward fixation during hovering.

  • 41. O’Carroll, David C
    et al.
    Barnett, Paul
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Temporal and spatial adaptation of transient responses to local features2012In: Frontiers in Neural Circuits, ISSN 1662-5110, E-ISSN 1662-5110, Vol. 6, no Article 74, p. 1-12Article in journal (Refereed)
    Abstract [en]

    Interpreting visual motion within the natural environment is a challenging task, particularly considering that natural scenes vary enormously in brightness, contrast and spatial structure. Current models for the detection of self-generated optic flow depend heavily on these very parameters, but despite this, animals manage to successfully navigate within a broad range of scenes. Within global scenes local areas with more salient features are common. Recent work has highlighted the influence that local, salient features have on the encoding of optic flow, but it has been difficult to quantify how local transient responses affect responses to subsequent features and thus contribute to the global neural response. To investigate this in more detail we used experimenter-designed stimuli and recorded intracellularly from motion-sensitive neurons. We limited the stimulus to a small vertically elongated strip, to investigate local and global neural responses to pairs of local ᅵdoubletᅵ features that were designed to interact with each other in the temporal and spatial domain. We show that the passage of a high contrast doublet feature produces a complex transient response from local motion detectors consistent with predictions of a simple computational model. In the neuron, the passage of a high-contrast feature induces a local reduction in responses to subsequent low contrast features. However, this neural contrast gain reduction appears to be recruited only when features stretch vertically (i.e. orthogonal to the direction of motion) across at least several aligned neighbouring ommatidia. Horizontal displacement of the components of elongated features abolishes the local adaptation effect. It is thus likely that features in natural scenes with vertically aligned edges, such as tree trunks, would be expected to recruit the greatest amount of response suppression, which could emphasize the local responses to such features vs those in nearby texture within the scene.

  • 42.
    Outomuro, David
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Söderquist, Linus
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Johansson, Frank
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Ödeen, Anders
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Animal ecology.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology. Flinders Univ S Australia, Anat & Histol Ctr Neurosci, GPO Box 2100, Adelaide, SA 5001, Australia..
    The price of looking sexy: visual ecology of a three-level predator–prey system2017In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 31, no 3, p. 707-718Article in journal (Refereed)
    Abstract [en]

    Colour signals and colour vision play a pivotal role in intraspecific communication and predator-prey interactions. However, the costs of expressing conspicuous sexual signals at multiple trophic levels have been largely overlooked. Sexual signals can also experience character displacement in sympatric populations of closely related species, leading to potential changes in conspicuousness. We here investigate a bird-damselfly-fruit fly predator-prey system, where two closely related damselfly species have conspicuous, sexually selected wing coloration. The damselflies can occur in sympatry and allopatry, and reproductive character displacement in the coloration size has been previously reported. We quantify the damselfly wing reflectance from replicated sympatric and allopatric populations, and use receptor noise models to investigate the visual discriminability of the wing coloration for the bird, damselfly and fly vision systems, against natural backgrounds. We perform electroretinograms to study damselfly eye sensitivity. We also estimate damselfly predation risk in natural populations. We find that the chromatic component of wing coloration makes males highly discriminable to the predator, but not to the prey. However, female wing coloration is predominantly cryptic for the predator and prey, and interestingly, also for male damselflies. A female being cryptic to conspecifics likely reduces male harassment. The estimates of predation risk partially support the discriminability results. We also show that there is no difference in colour vision sensitivity between the two damselfly species and sexes, and no difference in wing coloration or its discriminability between sympatric and allopatric populations. Our results suggest that sexually selected traits can be antagonistically selected by predators and prey and that this antagonistic selection can be sex-dependent: males are paying a large cost in terms of conspicuousness, while females remain mostly cryptic. Our study thus emphasizes the need for investigating visual communication at multitrophic levels since the degree of colour discriminability can differ between predators, prey and the focal species.

  • 43.
    Thyselius, Malin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Gonzalez-Bellido, Paloma
    Univ Cambridge, Dept Physiol Dev & Neurosci, Cambridge, England.
    Wardill, Trevor
    Univ Cambridge, Dept Physiol Dev & Neurosci, Cambridge, England.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Visual approach computation in feeding hoverflies2018In: Journal of Experimental Biology, ISSN 0022-0949, E-ISSN 1477-9145, Vol. 221, no 10, article id jeb.177162Article in journal (Refereed)
    Abstract [en]

    On warm sunny days, female hoverflies are often observed feeding from a wide range of wild and cultivated flowers. In doing so, hoverflies serve a vital role as alternative pollinators, and are suggested to be the most important pollinators after bees and bumblebees. Unless the flower hoverflies are feeding from is large, they do not readily share the space with other insects, but instead opt to leave if another insect approaches. We used high-speed videography followed by 3D reconstruction of flight trajectories to quantify how female Eristalis hoverflies respond to approaching bees, wasps and two different hoverfly species. We found that, in 94% of the interactions, the occupant female left the flower when approached by another insect. We found that compared with spontaneous take-offs, the occupant hoverfly's escape response was performed at similar to 3 times higher speed (spontaneous take-off at 0.20.05 m s(-1) compared with 0.55 +/- 0.08 m s(-1) when approached by another Eristalis). The hoverflies tended to take off upward and forward, while taking the incomer's approach angle into account. Intriguingly, we found that, when approached by wasps, the occupant Eristalis took off at a higher speed and when the wasp was further away. This suggests that feeding hoverflies may be able to distinguish these predators, demanding impressive visual capabilities. Our results, including quantification of the visual information available before occupant take-off, provide important insight into how freely behaving hoverflies perform escape responses from competitors and predators (e.g. wasps) in the wild.

  • 44.
    Thyselius, Malin
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology. Flinders Univ S Australia, Ctr Neurosci, Anat & Histol, Adelaide, SA 5001, Australia.
    Hoverfly locomotor activity is resilient to external influence and intrinsic factors2016In: Journal of Comparative Physiology A. Sensory, neural, and behavioral physiology, ISSN 0340-7594, E-ISSN 1432-1351, Vol. 202, no 1, p. 45-54Article in journal (Refereed)
    Abstract [en]

    Hoverflies are found across the globe, with approximately 6000 species described worldwide. Many hoverflies are being used in agriculture and some are emerging as model species for laboratory experiments. As such it is valuable to know more about their activity. Like many other dipteran flies, Eristalis hoverflies have been suggested to be strongly diurnal, but this is based on qualitative visualization by human observers. To quantify how hoverfly activity depends on internal and external factors, we here utilize a locomotor activity monitoring system. We show that Eristalis hoverflies are active during the entire light period when exposed to a 12 h light:12 h dark cycle, with a lower activity if exposed to light during the night. We show that the hoverflies' locomotor activity is stable over their lifetime and that it does not depend on the diet provided. Surprisingly, we find no difference in activity between males and females, but the activity is significantly affected by the sex of an accompanying conspecific. Finally, we show that female hoverflies are more resilient to starvation than males. In summary, Eristalis hoverflies are resilient to a range of internal and external factors, supporting their use in long-term laboratory experiments.

  • 45. Wardill, T. J.
    et al.
    Knowles, K.
    Barlow, L.
    Tapia, G.
    Nordström, Karin
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience, Physiology.
    Olberg, R. M.
    Gonzalez-Bellido, P. T.
    The Killer Fly Hunger Games: Target Size and Speed Predict Decision to Pursuit2015In: Brain, behavior, and evolution, ISSN 0006-8977, E-ISSN 1421-9743, Vol. 86, no 1, p. 28-37Article in journal (Refereed)
    Abstract [en]

    Predatory animals have evolved to optimally detect their prey using exquisite sensory systems such as vision, olfaction and hearing. It may not be so surprising that vertebrates, with large central nervous systems, excel at predatory behaviors. More striking is the fact that many tiny insects, with their miniscule brains and scaled down nerve cords, are also ferocious, highly successful predators. For predation, it is important to determine whether a prey is suitable before initiating pursuit. This is paramount since pursuing a prey that is too large to capture, subdue or dispatch will generate a substantial metabolic cost (in the form of muscle output) without any chance of metabolic gain (in the form of food). In addition, during all pursuits, the predator breaks its potential camouflage and thus runs the risk of becoming prey itself. Many insects use their eyes to initially detect and subsequently pursue prey. Dragonflies, which are extremely efficient predators, therefore have huge eyes with relatively high spatial resolution that allow efficient prey size estimation before initiating pursuit. However, much smaller insects, such as killer flies, also visualize and successfully pursue prey. This is an impressive behavior since the small size of the killer fly naturally limits the neural capacity and also the spatial resolution provided by the compound eye. Despite this, we here show that killer flies efficiently pursue natural <i>(Drosophila melanogaster)</i> and artificial (beads) prey. The natural pursuits are initiated at a distance of 7.9 ± 2.9 cm, which we show is too far away to allow for distance estimation using binocular disparities. Moreover, we show that rather than estimating absolute prey size prior to launching the attack, as dragonflies do, killer flies attack with high probability when the ratio of the prey's subtended retinal velocity and retinal size is 0.37. We also show that killer flies will respond to a stimulus of an angular size that is smaller than that of the photoreceptor acceptance angle, and that the predatory response is strongly modulated by the metabolic state. Our data thus provide an exciting example of a loosely designed matched filter to <i>Drosophila</i>, but one which will still generate successful pursuits of other suitable prey.

1 - 45 of 45
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf