The Anatomy of Manual Dexterity

The macaque monkey uses the hand to grasp, digitally explore, and identify objects within reach, and to use them intelligently. This review is focused on the topography and connections of some of the neuron populations that determine this manual dexterity. In the last decade these neuron populations have been analyzed using modern axon tracer techniques, single neuron recording in the alert monkey, and PET, resulting in a serious reconsideration of their structural and functional organization, and their roles in voluntary action. This review critically examines some of the new ideas triggered by these observations.