Macaque Ventral Premotor Cortex Exerts Powerful Facilitation of Motor Cortex Outputs to Upper Limb Motoneurons

• Published in: The Journal of neuroscience 2004-02, Vol.24 (5), p.1200-1211
• Main Authors: Shimazu, H, Maier, M. A, Cerri, G, Kirkwood, P. A, Lemon, R. N
• Format: Article
• Language: English
• Subjects: Animals; Electric Stimulation; Electrodes, Implanted; Excitatory Postsynaptic Potentials - physiology; Frontal Lobe - physiology; GABA Agonists - pharmacology; Macaca fascicularis - physiology; Macaca mulatta - physiology; Microinjections; Motor Cortex - drug effects; Motor Cortex - physiology; Motor Neurons - physiology; Research Support, Non-U.S. Gov't; Upper Extremity - physiology
• ISSN: 0270-6474; 1529-2401
• DOI: 10.1523/JNEUROSCI.4731-03.2004

The ventral premotor area (F5) is part of the cortical circuit controlling visuomotor grasp. F5 could influence hand motor function through at least two pathways: corticospinal projections and corticocortical projections to primary motor cortex (M1). We found that stimulation of macaque F5, which by itself evoked little or no detectable corticospinal output, could produce a robust modulation of motor outputs from M1. Arrays of fine microwires were implanted in F5 and M1. During terminal experiments under chloralose anesthesia, single stimuli delivered to M1 electrodes evoked direct (D) and indirect (I1,I2, and I3) corticospinal volleys. In contrast, single F5 shocks were ineffective; double shocks (3 msec separation) evoked small I waves but no D wave. However, when the test (T) M1 shock was conditioned (C) by single or double F5 shocks, there was strong facilitation of I2 and I3 waves from M1, with C-T intervals of