Document Detail

Binocularity in the little owl, Athene noctua. II. Properties of visually evoked potentials from the Wulst in response to monocular and binocular stimulation with sine wave gratings.
MedLine Citation:
PMID:  2340414     Owner:  NLM     Status:  MEDLINE    
Visually evoked potentials (VEPs) have been recorded from the Wulst surface of the little owl, Athene noctua, in response to counterphase-reversal of sinusoidal gratings with different contrast, spatial frequency and mean luminance, presented either monocularly or binocularly. Monocular full-field stimuli presented to either eye evoked VEPs of similar amplitude, waveform and latency. Under binocular viewing, VEPs approximately doubled in amplitude without waveform changes. VEPs with similar characteristics could be obtained in response to stimulation of the contralateral, but not ipsilateral, hemifield. These results suggest that a 50% recrossing occurs in thalamic efferents and that different ipsilateral and contralateral regions converge onto the same Wulst sites. The VEP amplitude progressively decreased with increase of the spatial frequency beyond 2 cycles/degree, and the high spatial frequency cut-off (VEP acuity) was under binocular viewing (8 cycles/degree) higher than under monocular (5 cycles/degree) viewing (200 cd/m2, 45% contrast). The VEP acuity increased with increase in the contrast and decreased with reduction of the mean luminance. The binocular gain in both VEP amplitude and VEP acuity was largest at the lowest luminance levels. Binocular VEP summation occurred in the medium-high contrast range. With decreased contrast, both monocular and binocular VEPs progressively decreased in amplitude and tended to the same contrast threshold. The VEP contrast threshold depended on the spatial frequency (0.6-1.8% in the range 0.12-2 cycles/degree). Binocular VEPs often showed facilitatory interaction (binocular/monocular amplitude ratio greater than 2), but the binocular VEP amplitude did not change either by changing the stimulus orientation (horizontal vs. vertical gratings) or by inducing different retinal disparities.(ABSTRACT TRUNCATED AT 250 WORDS)
V Porciatti; G Fontanesi; A Raffaelli; P Bagnoli
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Brain, behavior and evolution     Volume:  35     ISSN:  0006-8977     ISO Abbreviation:  Brain Behav. Evol.     Publication Date:  1990  
Date Detail:
Created Date:  1990-06-27     Completed Date:  1990-06-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  0151620     Medline TA:  Brain Behav Evol     Country:  SWITZERLAND    
Other Details:
Languages:  eng     Pagination:  40-8     Citation Subset:  IM    
Ophthalmology Division, USL 13, Livorno, Italy.
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MeSH Terms
Attention / physiology
Birds / physiology*
Brain Mapping
Dark Adaptation / physiology
Dominance, Cerebral / physiology*
Evoked Potentials, Visual / physiology*
Form Perception / physiology*
Neurons / physiology
Optic Nerve / physiology*
Pattern Recognition, Visual / physiology*
Photic Stimulation
Retina / physiology
Sensory Thresholds / physiology
Thalamic Nuclei / physiology
Vision Disparity / physiology
Vision, Binocular / physiology*
Visual Cortex / physiology*
Visual Fields / physiology
Visual Pathways / physiology

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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