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, 34 (5), 841-51

Complex Movements Evoked by Microstimulation of Precentral Cortex


Complex Movements Evoked by Microstimulation of Precentral Cortex

Michael S A Graziano et al. Neuron.


Electrical microstimulation was used to study primary motor and premotor cortex in monkeys. Each stimulation train was 500 ms in duration, approximating the time scale of normal reaching and grasping movements and the time scale of the neuronal activity that normally accompanies movement. This stimulation on a behaviorally relevant time scale evoked coordinated, complex postures that involved many joints. For example, stimulation of one site caused the mouth to open and also caused the hand to shape into a grip posture and move to the mouth. Stimulation of this site always drove the joints toward this final posture, regardless of the direction of movement required to reach the posture. Stimulation of other cortical sites evoked different postures. Postures that involved the arm were arranged across cortex to form a map of hand positions around the body. This stimulation-evoked map encompassed both primary motor and the adjacent premotor cortex. We suggest that these regions fit together into a single map of the workspace around the body.

Comment in

  • Reaching for Answers
    RJ Krauzlis. Neuron 34 (5), 673-4. PMID 12062014. - Review
    The exact function of motor cortex continues to be an enigma. In this issue of Neuron, present provocative data showing that microstimulation of the precentral cortex evo …

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