Limit of spared pattern vision following lesions of the immature visual cortex |
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Authors: | Email author" target="_blank">Bertram?R?PayneEmail author |
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Institution: | (1) Cerebral Dynamics, Plasticity and Rehabilitation, W702, Department of Anatomy and Neurobiology, Center for Advanced Biomedical Research, Boston University School of Medicine, 700 Albany Street, MA 02118, Boston, USA, |
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Abstract: | Lesions of primary visual cortex sustained early in life spare certain aspects of visual processing that can be linked to
expansions of bypass pathways to extrastriate cortex. They also trigger, in an age-dependent way, partial or complete transneuronal
retrograde degeneration of β (X) retinal ganglion cells, which are implicated in visual processing under conditions of low
contrast. We used two-dimensional geometric patterns whose saliency was reduced by gradually increasing levels of superimposed
masking lines, and by reductions in spatial contrast. Normative data were collected from intact cats, and baseline lesion
data were collected from cats with lesions sustained as young adults (postnatal day 180, P180). Experimental data were collected
from cats that sustained lesions on P1–3 or P26–30. For high contrast patterns, the adult group was impaired at both acquisition
(sequential progressive levels of masking) and concurrent (parallel high and low levels of masking) performance, whereas the
early-lesioned groups were impaired only at concurrent performance. All lesion groups were equally impaired when contrast
was reduced to modest or lower levels. These results show that sparing of masked-pattern learning is limited to the high end
of the spatial contrast domain.
Electronic Publication |
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Keywords: | Areas 17 and 18 X-System β Ganglion cells Acuity Rewiring of circuits Neuroplasticity Contrast Human |
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