Agenesis of which major brain commissure results in impaired interhemispheric communication?

Agenesis of which major brain commissure results in impaired interhemispheric communication?

• A. Anterior commissure
• B. Corpus callosum
• C. Pyramidal decussation
• D. Fornix

Answer: (B)

Interhemispheric communication mainly relies on a large bundle of axons that spans the two cerebral hemispheres. The corpus callosum is that primary bridge, containing hundreds of millions of fibers that wire almost every cortical area to its counterpart on the opposite side. When the corpus callosum fails to develop (agenesis), the most important route for cross-hemisphere signaling is missing, leading to impaired coordination and integration of information between the two sides of the brain. The anterior commissure, while it does connect the two hemispheres, is much smaller and mainly links parts of the temporal lobes and olfactory regions, not the whole cortex. The pyramidal decussation is where corticospinal fibers cross in the brainstem/spinal cord, affecting motor control rather than cortical interhemispheric transfer. The fornix connects the hippocampus with limbic structures, not the two hemispheres broadly.

Interhemispheric communication mainly relies on a large bundle of axons that spans the two cerebral hemispheres. The corpus callosum is that primary bridge, containing hundreds of millions of fibers that wire almost every cortical area to its counterpart on the opposite side. When the corpus callosum fails to develop (agenesis), the most important route for cross-hemisphere signaling is missing, leading to impaired coordination and integration of information between the two sides of the brain. The anterior commissure, while it does connect the two hemispheres, is much smaller and mainly links parts of the temporal lobes and olfactory regions, not the whole cortex. The pyramidal decussation is where corticospinal fibers cross in the brainstem/spinal cord, affecting motor control rather than cortical interhemispheric transfer. The fornix connects the hippocampus with limbic structures, not the two hemispheres broadly.