Chapter

The Motor Cortical Circuit

Apostolos P. Georgopoulos and Costas N. Stefanis

in Handbook of Brain Microcircuits

Published on behalf of Oxford University Press

Published in print August 2010 | ISBN: 9780195389883
Published online September 2012 | e-ISBN: 9780199965137 | DOI: http://dx.doi.org/10.1093/med/9780195389883.003.0005
The Motor Cortical Circuit

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This chapter reviews the basic layout of the motor cortical circuit (MCC) as well as its spatial, temporal, and behavioral aspects, with an emphasis on recurrent inhibition. The MCC operates as an integrated network at the greater MCC (gMCC) level. The output of which is an orderly tuning function. This tuning function can refer to the direction of arm movement in space in the arm area or to a combination of finger movements in the hand area of the motor cortex. It is likely that a suitable tuning function pertains in different parts of the motor cortex, depending on the relevant parameters dictated by the somatotopic arrangement. For example, tuning of motor cortical cells with respect to the direction of tongue protrusion is described in the orofacial area of the motor cortex. In real time, external, synchronous, excitatory, and converging inputs to the relevant part of the motor cortex would initiate gMCC activation and pyramidal cell discharge; within a short time (a few tens of milliseconds), recurrent excitatory and inhibitory actions would ensure the shaping of the local motor cortical landscape, enhancing activity at its center (by boosting excitation) and gradually reducing activity at its periphery (by recurrent inhibition), that is, enhancing the motor contrast.

Chapter.  2142 words.  Illustrated.

Subjects: Development of the Nervous System

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