Intact hemisphere and corpus callosum compensate for visuomotor functions after early visual cortex damage

Area of Science:

• Neuroscience
• Visual Neuroscience
• Developmental Neuroscience

Background:

• Unilateral primary visual cortex (V1) damage causes hemifield blindness.
• Blindsight demonstrates retained nonconscious visual processing despite V1 lesions.
• Investigating brain plasticity in early V1 damage is crucial for understanding recovery.

Observation:

• A single patient with early V1 lesion and blindsight was studied using psychophysics, fMRI, and tractography.
• Visual stimuli were presented to intact and blind hemifields, with motor responses from ipsilateral and contralateral hands.
• This design allowed examination of same- vs. opposite-hemisphere visuomotor processing.

Findings:

• The corpus callosum (CC) dynamically recruited dorsal stream and premotor areas in the intact hemisphere.
• This recruitment compensated for altered visuomotor functions when the V1-damaged hemisphere was stimulated or controlled responses.
• Increased CC connectivity in posterior regions, linking parietal cortices, paralleled functional compensation.

Implications:

• The developing brain exhibits remarkable plasticity following early V1 lesions.
• The corpus callosum plays a key role in interhemispheric compensation for visual field deficits.
• Findings offer insights into neural mechanisms underlying recovery from early visual cortex injury.