Selective visual neglect in right brain damaged patients with splenial interhemispheric disconnection

Area of Science:

• Neuroscience
• Neurology
• Cognitive Science

Background:

• Left unilateral neglect typically follows right hemispheric lesions, particularly those affecting the middle cerebral artery (MCA) pathway.
• However, neglect can also occur with posterior cerebral artery (PCA) lesions, suggesting alternative mechanisms beyond direct parietal-frontal network damage.

Observation:

• This study examined two patients with PCA lesions impacting the splenium of the corpus callosum and the adjacent right primary visual cortex.
• These lesions caused severe neglect specifically within the visual domain.

Findings:

• Unlike typical neglect, these patients showed no personal, motor, or representational-imagery neglect.
• The neglect was exclusively visual, without associated motor or tactile deficits, distinguishing it from neglect caused by lesions in other callosal regions.

Implications:

• These findings demonstrate that spatial neglect can arise from disruptions in sensory input to attentional areas, even without direct damage to those areas.
• This suggests that specific sensory modalities or spatial sectors can be selectively affected by lesions that disconnect sensory information from higher-order processing regions.