Angela Sirigu - US grants

Neural Plasticity and Functional Adaptation in the Human Brain
Abstract

With National Science Foundation support, Drs. Scheiber and Sirigu and colleagues will conduct a three-year investigation of adult human amputees who will undergo bilateral hand transplantation. Brain imaging, stimulation, and recordings of muscle activity underlying finger movements-all will be applied longitudinally before, and at intervals after, hand transplantation to address the following experimental questions. (1) Is reorganization limited to the cortical representation of the grafted hand, or does it involve additional body segments? (2) Is reorganization observed in the primary motor cortex correlated with changes occurring in the homologous regions of the primary sensory cortex? (3) Upon loss of the hands, does use-dependent reorganization in the sensorimotor cortex result in a loss of motor skills, which must be reacquired when the hands are restored? (4) Does re-expansion of the motor cortex hand representation correlate with the return of motor skill? The parts of brain studied in this project are the primary somatosensory and primary motor cortices, which contain the most detailed maps of bodily sensation and movement in the brain. These representational maps undergo considerable reorganization, however, in response to altered sensory stimulation, behavioral use, or amputation of a body part, such as the hand. After amputation, the cortical territory that has been deprived of its specific body part reorganizes to represent remaining nearby body parts. Amputation-induced reorganization occurs even in adult humans, and can occur rapidly and reversibly. Little is known, however, about the reversibility of such plastic reorganization months to years after amputation, when structural changes in nerve cells and their interconnections have had time to occur. Transplantation to replace amputated body parts offers the opportunity to study the reversibility of reorganization in the primary somatosensory and motor cortex after such long-term changes. The results of these studies will expand our basic understanding of how representations of bodily movement in the sensorimotor cortex are shaped and re-shaped by plastic reorganization.