The Decerebrate State in the Primate: II. Studies in Man

Electromyographic analysis of postural reflexes in (1) patients considered “decerebrate,” ie, manifesting the signs reported in monkeys with brain stem transection, (2) patients with upper motoneuron disorders, and (3) normal controls revealed in all groups a stereotyped extensor posturing especially of the forelimbs, called the reactive extensor postural synergy (REPS), with increased amplitude of response the only difference between patients with rostral brain disconnection and control subjects. Therefore, the primate central nervous system has an intrinsic pattern of extensor neck and limb responses, lacking in absolute reciprocal inhibition. Its threshold is lowered in relative isolation of the brain stem. The term decerebrate rigidity is rejected, as it implies a continually manifest condition of extension. Rather, the term decerebrate state indicates the collective sum of reflexes, including REPS, posture and tone as are seen in the brain stem transected monkey.