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Lee, Yu-Jen
Publications (4 of 4) Show all publications
de Haan, R., Lee, Y.-J. & Nordström, K. (2013). Novel Flicker-Sensitive Visual Circuit Neurons Inhibited by Stationary Patterns. Journal of Neuroscience, 33(21), 8980-8989
Open this publication in new window or tab >>Novel Flicker-Sensitive Visual Circuit Neurons Inhibited by Stationary Patterns
2013 (English)In: Journal of Neuroscience, ISSN 0270-6474, E-ISSN 1529-2401, Vol. 33, no 21, p. 8980-8989Article in journal (Refereed) Published
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.

National Category
Neurosciences
Identifiers
urn:nbn:se:uu:diva-200302 (URN)10.1523/JNEUROSCI.5713-12.2013 (DOI)000319391200007 ()23699509 (PubMedID)
Funder
Swedish Research Council
Available from: 2013-05-24 Created: 2013-05-24 Last updated: 2018-01-11Bibliographically approved
Lee, Y.-J. & Nordström, K. (2012). Higher-order motion sensitivity in fly visual circuits. Proceedings of the National Academy of Sciences of the United States of America, 109(22), 8758-8763
Open this publication in new window or tab >>Higher-order motion sensitivity in fly visual circuits
2012 (English)In: 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) Published
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.

Keywords
elementary motion detector, neural delays, sexual dimorphism, bar motion
National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-176824 (URN)10.1073/pnas.1203081109 (DOI)000304881700079 ()
Available from: 2012-06-27 Created: 2012-06-26 Last updated: 2017-12-07Bibliographically approved
de Haan, R., Lee, Y.-J. & Nordström, K. (2012). Octopaminergic modulation of contrast sensitivity. Frontiers in Integrative Neuroscience, 6(Article 55)
Open this publication in new window or tab >>Octopaminergic modulation of contrast sensitivity
2012 (English)In: Frontiers in Integrative Neuroscience, ISSN 1662-5145, E-ISSN 1662-5145, Vol. 6, no Article 55Article in journal (Refereed) Published
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.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-181382 (URN)10.3389/fnint.2012.00055 (DOI)22876224 (PubMedID)
Available from: 2012-09-25 Created: 2012-09-24 Last updated: 2017-12-07Bibliographically approved
Boije, H., Harun-Or-Rashid, M., Lee, Y.-J., Imsland, F., Bruneau, N., Vieaud, A., . . . Hallböök, F. (2012). Sonic Hedgehog-Signalling Patterns the Developing Chicken Comb as Revealed by Exploration of the Pea-comb Mutation. PLoS ONE, 7(12), e50890
Open this publication in new window or tab >>Sonic Hedgehog-Signalling Patterns the Developing Chicken Comb as Revealed by Exploration of the Pea-comb Mutation
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2012 (English)In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 12, p. e50890-Article in journal (Refereed) Published
Abstract [en]

The genetic basis and mechanisms behind the morphological variation observed throughout the animal kingdom is stillrelatively unknown. In the present work we have focused on the establishment of the chicken comb-morphology byexploring the Pea-comb mutant. The wild-type single-comb is reduced in size and distorted in the Pea-comb mutant. Peacombis formed by a lateral expansion of the central comb anlage into three ridges and is caused by a mutation in SOX5,which induces ectopic expression of the SOX5 transcription factor in mesenchyme under the developing comb. Analysis ofdifferential gene expression identified decreased Sonic hedgehog (SHH) receptor expression in Pea-comb mesenchyme. Byexperimentally blocking SHH with cyclopamine, the wild-type single-comb was transformed into a Pea-comb-likephenotype. The results show that the patterning of the chicken comb is under the control of SHH and suggest that ectopicSOX5 expression in the Pea-comb change the response of mesenchyme to SHH signalling with altered combmorphogenesis as a result. A role for the mesenchyme during comb morphogenesis is further supported by the recentfinding that another comb-mutant (Rose-comb), is caused by ectopic expression of a transcription factor in combmesenchyme. The present study does not only give knowledge about how the chicken comb is formed, it also adds to ourunderstanding how mutations or genetic polymorphisms may contribute to inherited variations in the human face.

National Category
Medical and Health Sciences
Identifiers
urn:nbn:se:uu:diva-187458 (URN)10.1371/journal.pone.0050890 (DOI)000312588200079 ()
Available from: 2012-12-07 Created: 2012-12-06 Last updated: 2017-12-07Bibliographically approved
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