Proceedings of The Physiological Society

University College London December 2005 (2006) Proc Physiol Soc 1, C11

Oral Communications

Activity of callosal neurons in primate SMA during a bimanual precision grip task

Soteropoulos, Demetris; Baker, Stuart N;

1. University of Newcastle, Newcastle Upon Tyne, United Kingdom.

  • Figure 1. Task-related modulation in firing rate.

The supplementary motor area (SMA) is important in bimanual motor control; although dense callosal connections serve to link SMA in each hemisphere, little is known about the firing patterns of these cells. We here report recordings from antidromically identified corpus callosum (CC) neurons in the hand representation of SMA, in two m. mulatta monkeys trained to perform a bimanual precision grip task for food reward. The monkeys initiated the task by placing both hands on home pads. Audiovisual cues indicated whether right hand, left hand or both were to be used, and following an instructed delay, the monkeys reached out and performed a precision grip (1s hold period). After training was complete, the monkeys were implanted (under full general anaesthesia: 1.52.5% isoflurane inhalation in 50:50 N2O:O2 and aseptic conditions) with a stainless steel headpiece to allow atraumatic head fixation and a recording chamber sited above a craniotomy exposing SMA. Single units were recorded in daily microelectrode penetrations whilst the animals performed the trained task. CC neurons were identified antidromically by stimulation through chronically implanted electrodes in the corpus callosum close to the midline. Thirty-five CC units were encountered, and 13 units were recorded long enough to permit firing rate analysis (e10 trials per task type). The mean antidromic latency was 1.8ms (22/35 had latencies < 1.8ms; 4/35 had latencies > 3ms). CC neurons had low mean firing rates during the trial for all three movement types, at 3.7

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