Cortical reorganization in the adult primary sensorimotor cortex

Seminal work on sensorimotor plasticity has established the notion that the adult cortex has the capacity to functionally reorganize in order to adapt itself to the changed capabilities of the body. Limb loss provides a key model for studying brain reorganization as it combines two main drivers of brain plasticity—sensory input loss and altered behavior. Here we explore how the highly structured and consistent hand representation in the primary somatosensory cortex (S1) changes following hand loss. We review classical findings demonstrating that following amputation, the neighboring body part representations “invade” the deprived hand area. We further review potential perceptual consequences of such reorganization, both maladaptive (e.g., phantom limb pain) and adaptive (e.g., compensatory strategies). We highlight recent evidence demonstrating that the functional organization in the deprived cortex is preserved even decades after amputation, consistent with the view that S1 reorganization reflects plasticity occurring at the brainstem level. Finally we highlight alternative models of deprivation-driven S1 plasticity, such as hand transplantation, temporary deafferentation, congenital handlessness, and neuroprostheses, providing further insights into the scope and functional consequences of S1 reorganization.