Proceedings of The Physiological Society

University College London December 2005 (2006) Proc Physiol Soc 1, C13

Oral Communications

Time-specific activation of transcallosal projections between the left dorsal premotor and the right motor cortex during selection of movement in humans

Koch, Giacomo; Franca, Michele; Milton, Rosemary; Fernandez del Olmo, Miguel; Cheeran, Binith; Rothwell, John C;

1. Sobell Department of Motor Neuroscience and Movement Disorders, Institute of Neurology, University College London, London, United Kingdom. 2. Fondazione S. Lucia IRCCS, Rome, Italy.

The dorsal premotor cortex (PMd) has a role in selection of movements through a densely interconnected network linking the premotor areas and the motor cortex (MCx) of the two hemispheres. Mochizuki et al. (2004) recently described a method using paired pulse transcranial magnetic stimulation to explore the transcallosal projections connecting the PMd with the contralateral primary MCx. They found that the amplitude of EMG responses evoked by a standard TMS pulse to the left MCx could be modulated by applying a conditioning stimulus (CS) to the right PMd some 8-10 ms beforehand. Inhibition occurred if the intensity of the CS was 110% rest motor threshold (RMT). In another study facilitation was induced at a similar interstimulus interval (8 ms) using low intensity CS to the left PMd (CS=80% RMT) (T. B

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