HAND-MOUTH COORDINATION, CONGENITAL ABSENCE OF LIMB, AND EVIDENCE FORINNATE BODY SCHEMAS

Studies of phantom limb in cases of congenital (aplasic) absence of li mb have provided inadequate evidence concerning the innate neurologica l substrate responsible for the phantom. In this study we review evide nce from ultrasonic and behavioral studies of hand-mouth coordination in utero and in early infancy, neurobiological studies in primates, an d studies of neural reorganization following amputation. We suggest tw o complementary hypotheses to explain aplasic phantoms. First, aplasic phantoms are based on the existence of specific neural circuitry asso ciated with innate motor schemas, such as the neural matrix responsibl e for early hand-mouth coordination. Second, aplasic phantoms are modi fied by mechanisms that involve a reorganization of neural representat ions of the missing limb within a complex network involving both corti cal and subcortical structures. (C) 1998 Academic Press.