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November 1965

Spontaneous Activity in the Pyramidal Tract of Chronic Cats and Monkeys: Recorded with Indwelling Electrodes

Author Affiliations

From the Department of Neurology and the Beaumont-May Institute of Neurology, Washington University School of Medicine, St. Louis. Dr. Hardin is a US Public Health Service Special Fellow.

Arch Neurol. 1965;13(5):501-512. doi:10.1001/archneur.1965.00470050049006

THE FUNCTIONAL significance of the pyramidal tract and the central cortical area in the role of movement has been a subject of controversy since the latter part of the 19th century. Electrophysiological studies in the form of recording from or stimulating these structures have been done under the tacit assumption that the patterned responses so obtained may represent "true units of function, not materially changed from the normal despite the abnormality of the method."1

Leyton and Sherrington2 and Brown and Sherrington3 studied the character of muscular responses obtained by stimulating the motor (precentral) cortex of the higher apes. They described what they saw as "fractional movements," which were "local items of movement, perfect within themselves." In addition they reported three characteristic aberrations in cortical responsiveness which depended upon a number of spatial and temporal factors relating to the manner of stimulation. They related these phenomena to

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