Symmetry in frontal but not motor and somatosensory corticocortical and corticostriatal circuitry.

The mammalian brain is divided into two cerebral hemispheres, each responsible for sensation and movement on the opposite side of the body. The two sides communicate via an enormous bundle of midline-crossing fibers, the corpus callosum. The callosal projections mainly target neocortex and striatum. While callosal projections originate from most areas of the neocortex, how the anatomy and function of these projections might vary across motor, sensory, and frontal regions is unknown. In particular, callosal projections are proposed here to play a large role in frontal areas, where maintaining unity across hemispheres in value assessment and decision-making for the whole individual is key, but a smaller role for sensory representations where perceptions from the contralateral body are less informative.