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  • 1. Anens, Elisabeth
    et al.
    Kristensen, Bo
    Häger-Ross, Charlotte
    Reactive grip force control in persons with cerebellar stroke: effects on ipsilateral and contralateral hand.2010In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 203, no 1Article in journal (Refereed)
    Abstract [en]

    This study investigates the cerebellar contribution to reactive grip control by examining differences between (22-48 years) subjects with focal cerebellar lesion due to ischaemic stroke (CL) and healthy subjects (HS). The subjects used a pinch grip to grasp and restrain an instrumented handle from moving when it was subject to unpredictable load forces of different rates (2, 4, 8, 32 N/s) or amplitudes (1, 2, 4 N). The hand ipsilateral to the lesion of the cerebellar subjects showed delayed and more variable response latencies, e.g., 278 +/- 162 ms for loads delivered at 2 N/s, compared to HS 180 +/- 53 ms (P = 0.005). The CL also used a higher pre-load grip force with the ipsilateral hand, 1.6 +/- 0.8 N, than the HS, 1.3 +/- 0.6 N (P = 0.017). In addition, the contralateral hand in subjects with unilateral cerebellar stroke showed a delayed onset of the grip response compared to HS. Cerebellar lesions thus impair the reactive grip control both in the ipsilateral and contralateral hand.

  • 2. Daum, Moritz M
    et al.
    Gredebäck, Gustaf
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    The Development of Grasping Comprehension in Infancy: Covert Shifts of Attention Caused by Referential Actions2011In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 208, no 2, p. 297-307Article in journal (Refereed)
    Abstract [en]

    An eye tracking paradigm was used to investigate how infants' attention is modulated by observed goal-directed manual grasping actions. In Experiment 1, we presented 3-, 5-, and 7-month-old infants with a static picture of a grasping hand, followed by a target appearing at a location either congruent or incongruent with the grasping direction of the hand. The latency of infants gaze shift from the hand to the target was recorded and compared between congruent and incongruent trials. Results demonstrate a congruency effect from 5 months of age. A second experiment illustrated that the congruency effect of Experiment 1 does not extend to a visually similar mechanical claw (instead of the grasping hand). Together these two experiments describe the onset of covert attention shifts in response to manual actions and relate these findings to the onset of manual grasping.

  • 3.
    Daum, Moritz
    et al.
    Univ Zurich, Dept Psychol, Binzmuehlestr 14,Box 21, CH-8050 Zurich, Switzerland.; Max Planck Inst Human Cognit & Brain Sci, Leipzig, Germany.
    Wronski, Caroline
    Univ Zurich, Dept Psychol, Binzmuehlestr 14,Box 21, CH-8050 Zurich, Switzerland.; Max Planck Inst Human Cognit & Brain Sci, Leipzig, Germany.; Univ Appl Sci, Potsdam, Germany.
    Harms, Annekatrin
    Max Planck Institute for Human Cognitive and Brain Sciences.
    Gredebäck, Gustaf
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Action perception in infancy: the plasticity of 7-month-olds’ attention to grasping actions2016In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 234, no 9, p. 2465-2478Article in journal (Refereed)
    Abstract [en]

    The present study investigates the plasticity of 7-month-old infants' orienting of attention during their perception of grasping actions. Previous research has shown that when infants observe a grasping hand, they shift their attention in line with the grasping direction, which is indicated by a reliable priming effect in this direction. The mechanisms behind this priming effect are largely unknown, and it is unclear how malleable this priming effect is with respect to a brief exposure to novel action-target contingencies. In a spatial-cueing paradigm, we presented a series of training trials prior to a series of test trials. These training sequences significantly modulated infants' attention. This suggests that action perception, when assessed through shifts of attention, is not solely based on the infants' grasping experience but quickly adapts to context-specific observed regularities.

  • 4.
    Diamantopoulou, Sofia
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Poom, Leo
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Klaver, Peter
    Talsma, Durk
    Visual working memory capacity and stimulus categories: a behavioral and electrophysiological investigation2011In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 209, no 4, p. 501-513Article in journal (Refereed)
    Abstract [en]

    It has recently been suggested that visual working memory capacity may vary depending on the type of material that has to be memorized. Here, we use a delayed match-to-sample paradigm and event-related potentials (ERP) to investigate the neural correlates that are linked to these changes in capacity. A variable number of stimuli (1-4) were presented in each visual hemifield. Participants were required to selectively memorize the stimuli presented in one hemifield. Following memorization, a test stimulus was presented that had to be matched against the memorized item(s). Two types of stimuli were used: one set consisting of discretely different objects (discrete stimuli) and one set consisting of more continuous variations along a single dimension (continuous stimuli). Behavioral results indicate that memory capacity was much larger for the discrete stimuli, when compared with the continuous stimuli. This behavioral effect correlated with an increase in a contralateral negative slow wave ERP component that is known to be involved in memorization. We therefore conclude that the larger working memory capacity for discrete stimuli can be directly related to an increase in activity in visual areas and propose that this increase in visual activity is due to interactions with other, non-visual representations.

  • 5.
    Ekberg, Therese L.
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Rosander, Kerstin
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    von Hofsten, Claes
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Olsson, Ulf
    Soska, Kasey C.
    Adolph, Karen E.
    Dynamic reaching in infants during binocular and monocular viewing2013In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 229, no 1, p. 1-12Article in journal (Refereed)
    Abstract [en]

    This study examined reaching in 6-, 8-, and 10-month-olds during binocular and monocular viewing in a dynamic reaching situation. Infants were rotated toward a flat vertical board and reached for objects at one of seven positions along a horizontal line at shoulder height. Hand selection, time to contact the object, and reaching accuracy were examined in both viewing conditions. Hand selection was strongly dependent on object location, not on infants' age or whether one eye was covered. Monocular viewing and age did, however, affect time to object contact and contact errors: Infants showed longer contact times when one eye was covered, and 6-month-olds made more contact errors in the monocular condition. For right-hand selection, contact times were longer when the covered right eye was leading during the chair rotation. For left-hand selection, there were no differences in contact time due to whether the covered eye was leading during rotation.

  • 6.
    Farrokhnia, Nasim
    et al.
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Roos, Magnus
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences, Clinical Physiology.
    Terént, Andreas
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Sciences.
    Lennmyr, Fredrik
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Surgical Sciences, Anaesthesiology and Intensive Care.
    Experimental treatment for focal hyperglycemic ischemic brain injury in the rat2005In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 167, no 2, p. 310-314Article in journal (Refereed)
    Abstract [en]

    Hyperglycemia aggravates ischemic brain injury, possibly due to the activation of signaling pathways involving reactive oxygen species, Src and mitogen-activated protein kinases. The aim of this study was to investigate the effects of the spin trap agent alpha-phenyl-N-tert-butyl nitrone (PBN), the Src family kinase inhibitor PP2 and the MEK1-inhibitor U0126 on focal hyperglycemic ischemic brain injury. Temporary middle cerebral artery occlusion (90 min) was induced in four groups of rats (PBN, PP2, and U0126 vs. control). Neurological testing and tetrazolium red staining were performed after 1 day. PBN decreased the infarct volume by 70% compared with the control (P<0.05) and a tendency towards reduced infarcts was seen in the PP2 or U0126 groups. Furthermore, neurological testing was consistent with the volumetric analysis. In conclusion, PBN appears to be a potential neuroprotective agent in hyperglycemic, focal ischemic brain injury, while the efficacy of PP2 and U0126 could not be confirmed by the present data.

  • 7.
    Gottwald, Janna M.
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Gredebäck, Gustaf
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Infants' prospective control during object manipulation in an uncertain environment2015In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 233, no 8, p. 2383-2390Article in journal (Refereed)
    Abstract [en]

    This study investigates how infants use visual and sensorimotor information to prospectively control their actions. We gave 14-month-olds two objects of different weight and observed how high they were lifted, using a Qualisys Motion Capture System. In one condition, the two objects were visually distinct (different color condition) in another they were visually identical (same color condition). Lifting amplitudes of the first movement unit were analyzed in order to assess prospective control. Results demonstrate that infants lifted a light object higher than a heavy object, especially when vision could be used to assess weight (different color condition). When being confronted with two visually identical objects of different weight (same color condition), infants showed a different lifting pattern than what could be observed in the different color condition, expressed by a significant interaction effect between object weight and color condition on lifting amplitude. These results indicate that (a) visual information about object weight can be used to prospectively control lifting actions and that (b) infants are able to prospectively control their lifting actions even without visual information about object weight. We argue that infants, in the absence of reliable visual information about object weight, heighten their dependence on non-visual information (tactile, sensorimotor memory) in order to estimate weight and pre-adjust their lifting actions in a prospective manner.

  • 8.
    Gredebäck, Gustaf
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Kochukhova, Olga
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Goal anticipation during action observation in influenced by synonymous action capabilities, a puzzling developmental study2010In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 202, p. 493-497Article in journal (Refereed)
  • 9.
    Gredebäck, Gustaf
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Kochukhova, Olga
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Goal anticipation during action observation is influenced by synonymous action capabilities, a puzzling developmental study2010In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, no 202, p. 493-497Article in journal (Refereed)
  • 10.
    Gredebäck, Gustaf
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Kochukhova, Olga
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Goal anticipation during action observation is influenced by synonymous action capabilities, a puzzling developmental study2010In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 202, no 2, p. 493-497Article in journal (Refereed)
    Abstract [en]

    Eighteen- and 25-month-old human toddlers' ability to manually solve a puzzle and their ability to anticipate the goal during observation of similar actions were investigated. Results demonstrate that goal anticipation during action observation is dependent on manual ability, both on a group level (only 25-month-olds solved the manual task and anticipated the goal during observation) and individually within the older age group (r (xy) = 0.53). These findings suggests a connection between manual ability and the ability to anticipate the goal of others' actions in toddlers, in accordance with the direct matching hypothesis.

  • 11.
    Gredebäck, Gustaf
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    von Hofsten, Claes
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Karlsson, Jessika
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Aus, Cathy
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    The development of two-dimensional tracking: a longitudinal study of circular pursuit2005In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 163, no 2, p. 204-213Article in journal (Refereed)
    Abstract [en]

    We investigated 6- to 12-month-old infants’ ability to track an object moving on circular trajectories, using a longitudinal design. Consistent predictive gaze tracking was not found before 8 months of age. These results indicate that infants’ horizontal and vertical components of circular tracking are less mature than expected from previous studies of one-dimensional horizontal tracking. Vertical components are especially immature, particularly during high velocity tracking (~20°/s). The results also suggest that horizontal and vertical tracking are mutually dependent during early development. Saccades were predictive (average lag >−125 ms) from 6 months onwards.

  • 12.
    Gredebäck, Gustaf
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Örnkloo, Helena
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    von Hofsten, Claes
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    The development of reactive saccade latencies2006In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 173, no 1, p. 159-164Article in journal (Refereed)
    Abstract [en]

    Saccadic reaction time (SRT) of 4-, 6- and 8-month-old infants' was measured during tracking of abruptly changing trajectories, using a longitudinal design. SRTs decreased from 595 ms (SE=30) at 4 months of age to 442 ms (SE=13) at 8 months of age. In addition, SRTs were lower during high velocities (comparing 4.5 and 9 degrees/s) and vertical (compared to horizontal) saccades.

  • 13.
    Grönqvist, Helena
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Brodd, Katarina Strand
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Women's and Children's Health.
    von Hofsten, Claes
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Reaching strategies of very preterm infants at 8 months corrected age2011In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 209, no 2, p. 225-233Article in journal (Refereed)
    Abstract [en]

    Reaching strategies and kinematics for a group of very preterm infants were investigated and compared with a group of full-term infants when reaching for a moving object. Eight-month-old (corrected-age) infants were presented with small toys moving on a semicircular path in the vertical plane. The trajectories of the target and the hands of the infants were measured using a 3D motion analysis system. No differences were found in how often the infants encountered the target. The very preterm group, however, used bimanual strategies more often and had more curved reaching paths than the full-term group. These results suggest that very preterm infants are equally successful as healthy full-term infants in catching a moving object but their reaching strategies are less efficient compared with full-term infants at 8 months (corrected age).

  • 14. Hasenöhrl, R U
    et al.
    Söderström, S
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Mohammed, A H
    Ebendal, Ted
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Neuroscience.
    Huston, J P
    Reciprocal changes in expression of mRNA for nerve growth factor and its receptors TrkA and LNGFR in brain of aged rats in relation to maze learning deficits1997In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 114, no 2, p. 205-213Article in journal (Refereed)
    Abstract [en]

    Quantitative in situ hybridization was used to examine the expression of mRNA for nerve growth factor (NGF) and its receptors, p140Trk (TrkA) and p75LNGFR (LNGFR), in different brain regions of adult (3-month-old) and aged (27-month-old) Wistar rats. The brain regions studied were hippocampus (dentate gyrus, CA3 region), basal forebrain (medial septum, diagonal band) and caudate-putamen. Prior to hybridization histochemistry behaviorally impaired as well as severely impaired animals were selected from a large group of old rats according to their performance in the Morris water maze. The impaired rats showed longer escape latencies and, thus, implicitly impaired performance in the place version of the task, but did not differ from adult controls on the platform crossing measure registered during the spatial probe trial. The severely impaired rats were significantly impaired on both measures, both in comparison with the adult animals and in comparison with the impaired aged rats. Inspection of the hippocampus revealed no age- or performance-related changes in NGF mRNA levels. The overall expression of TrkA mRNA in basal forebrain and caudate was found to be decreased in the impaired (-20%) as well as the severely impaired aged rats (-17%). A significant increase in p75LNGFR mRNA was found in the basal forebrain of the impaired rats in comparison with the severely impaired aged rats (+35%) and adult animals (+33%). These findings show that age-related maze performance deficits are accompanied by a decrease in basal forebrain and striatal TrkA mRNA expression. The increase in basal forebrain LNGFR mRNA levels observed in impaired, but not severely impaired, aged rats may reflect an early manifestation of processes underlying age-related cognitive deficits and may constitute a restorative and/or compensatory mechanism, since these rats displayed fewer deficits in navigation of the maze.

  • 15. Lee, Young Lim
    et al.
    Lind, Mats
    Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Division of Visual Information and Interaction. Uppsala University, Disciplinary Domain of Science and Technology, Mathematics and Computer Science, Department of Information Technology, Computerized Image Analysis and Human-Computer Interaction.
    Bingham, Geoffrey P.
    Perceived 3D metric (or Euclidean) shape is merely ambiguous, not systematically distorted2013In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 224, no 4, p. 551-555Article in journal (Refereed)
    Abstract [en]

    Many studies have reported that perceived shape is systematically distorted, but Lind et al. (Inf Vis 2:51-57, 2003) and Todd and Norman (Percept Psychophys 65:31-47, 2003) both found that distortions varied with tasks and observers. We now investigated the hypothesis that perception of 3D metric (or Euclidean) shape is ambiguous rather than systematically distorted by testing whether variations in context would systematically alter apparent distortions. The task was to adjust the aspect ratio of an ellipse on a computer screen to match the cross-section of a target elliptical cylinder object viewed in either frontoparallel elliptical cross-section (2D) or elliptical cross-section in depth (3D). Three different groups were tested using two tasks and two different ranges of aspect ratio: Group 1) 2D(Small) -> 3D(Large), Group 2) 2D(Large) -> 3D(Small), Group 3a) 2D(Small) -> 3D(Small), and Group 3b) 2D(Large) -> 3D(Large). Observers performed the 2D task accurately. This provided the context. The results showed the expected order of slopes when judged aspect ratios were regressed on actual aspect ratios: Group 1 (SL) < Group 3 (SS and LL) < Group 2 (LS). The ambiguity of perceived 3D aspect ratios allowed the range of aspect ratios experienced in the 2D task to affect the 3D judgments systematically. Nevertheless, when the 2D and 3D ranges of aspect ratios were the same (LL and SS) and the 2D were judged accurately, this did not yield accurate 3D judgments. The results supported the hypothesis that perceived 3D metric shape is merely ambiguous rather than systematically distorted.

  • 16. Melinder, Annika M. D.
    et al.
    Konijnenberg, Carolien
    Hermansen, Tone
    Daum, Moritz M.
    Gredebäck, Gustaf
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    The developmental trajectory of pointing perception in the first year of life2015In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 233, no 2, p. 641-647Article in journal (Refereed)
    Abstract [en]

    The present study investigated the development of the neural basis of pointing perception in 6-month- and 13-month-old infants. In a spatial-cueing paradigm, infants were presented with a peripheral target followed by a hand pointing toward (congruent condition) or away (incongruent condition) from the previously cued location. EEG responses to the presentation of the hand were measured. Thirteen-month-olds demonstrated larger amplitudes of ERP component P400 to incongruent compared to congruent pointing gestures over posterior temporal areas; 6-month-olds did not show any differential activation. This result suggests that the neural correlates of pointing perception undergo substantial development between 6 and 13 months of age.

  • 17. Nikkhah, G
    et al.
    Odin, P
    Smits, A
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, Ludwig Institute for Cancer Research.
    Tingström, A
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, Ludwig Institute for Cancer Research.
    Othberg, A
    Brundin, P
    Funa, K
    Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Medicinska och farmaceutiska vetenskapsområdet, centrumbildningar mm, Ludwig Institute for Cancer Research.
    Lindvall, O
    Platelet-derived growth factor promotes survival of rat and human mesencephalic dopaminergic neurons in culture1993In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 92, no 3, p. 516-523Article in journal (Refereed)
    Abstract [en]

    The effect of two isoforms of platelet-derived growth factor (PDGF), PDGF-AA and PDGF-BB, was tested on dissociated cell cultures of ventral mesencephalon from rat and human embryos. PDGF-BB but not PDGF-AA reduced the progressive loss of tyrosine hydroxylase- (TH)-positive neurons in rat and human cell cultures. The mean number of TH-positive cells in the PDGF-BB-treated rat culture was 64% and 106% higher than in the control cultures after 7 and 10 days in vitro, respectively. Corresponding figures for human TH-positive neurons were 90% and 145%. The influence of PDGF-BB was specific for TH-positive neurons and not a general trophic effect, since no change of either total cell number or metabolic activity was found. In PDGF-BB-treated cultures of human but not rat tissue the TH-positive neurons had longer neurites than observed in control or PDGF-AA-treated cultures. These data indicate that PDGF-BB may act as a trophic factor for mesencephalic dopaminergic neurons and suggest that administration of PDGF-BB could ameliorate degeneration and possibly promote axonal sprouting of these neurons in vivo.

  • 18.
    Rosander, Kerstin
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    von Hofsten, Claes
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Psychology.
    Development of gaze tracking of small and large objects2002In: Experimental Brain Research, ISSN 0014-4819, E-ISSN 1432-1106, Vol. 146, no 2, p. 257-264Article in journal (Refereed)
    Abstract [en]

    A longitudinal study was designed to address the relationships between the smooth pursuit (SP) and the optokinetic response (OKR). Eye and head movements were measured in infants between 7 and 14 weeks of age. They were placed in front of a moving object subtending visual angles of 2.5, 5, 7, 14, 21, 28, and 35°. The object oscillated sinusoidally along a horizontal path with a frequency of 0.25 Hz and an amplitude of  ±25° visual angle. It was found that the number of saccades was dependent on object size: at 6 and 9 weeks of age there were more saccades for the smallest objects. With increasing age, the number of saccades decreased. The composite eye movement gain (smooth tracking + saccades) did not change with age but for the 6.5-week group the gain was higher for smaller objects. The gain of the smooth eye tracking increased with age and showed no dependency on object size. In conclusion, the results do not support the concept of two separate systems, the OKR and the SP, each of them processing eye tracking of small and large objects. Finally, it was observed that two infants at 6.5 weeks of age who used considerable head movements did not inhibit the vestibular-ocular response.

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