Abstract
Electrical stimulation of area 24 causes respiratory, cardio-vascular and pupillary responses as well as pilorection. It also causes profound suppression of all motor activity, abolition of the deep reflexes and suppression of the electrical activity of the cerebral cortex. It may evoke complex bilateral tonic movements. Marchi degeneration extends from area 24 through the cerebral peduncles to the medial reticular formation of the pons. Ablation of area 24 causes a loss of fear of man, social indifference to fellow monkeys and loss of mimetic activity, grooming, and signs of affection.