4.23 - Neurological Specializations for Manual Gesture and Tool Use in Humans

Abstract

Primates possess a unique ability to manipulate their environments through dexterous use of the hands. Neuroantomical and physiological data from Old and New World monkeys suggest the existence of functionally specialized parietofrontal circuits involved in sensorimotor transformations that are necessary to control manual prehension (reaching, grasping, and object manipulation). Recent findings in macaques indicate that simple tool use behaviors may arise through experience-dependent changes within these representations. Although necessary, these sensorimotor transformations alone are insufficient to account for the complex tool use behaviors of ancestral and modern humans. These abilities require additional input from mechanisms that represent the physical properties of objects, and semantic knowledge concerning their acquired functions and uses. Data from human neuropsychology and functional neuroimaging suggest that a distributed network within the human left cerebral hemisphere may be critical for these semantically mediated actions.