RELATION OF THE CEREBRAL CORTEX TO THE GRASP REFLEX AND TO POSTURAL AND RIGHTING REFLEXES

Abstract

It has long been recognized that many of the postural reflexes described by Magnus cannot be demonstrated when the cerebral cortex is intact. The region of the cortex normally concerned in suppressing these reactions, however, has never been determined. Fulton and Keller¹could not elicit the postural neck reflexes in monkeys and chimpanzees from which one or both motor areas (area 4 of Brodmann) had been removed, and it has since been found in this laboratory that the thalamic righting reflexes are not obtainable in such preparations. Evidently, therefore, some other cortical area or areas are also concerned in suppressing these reactions. In a study of cortical pareses in monkeys²it was found that integrity of a portion of one premotor area (area 6a of Vogt) in animals from which both motor areas had been ablated made possible the execution of fairly well coordinated volitional movements in all