A comparative study of the effect of drugs on activating and vasomotor responses evoked by midbrain stimulation: atropine, pentobarbital, chlorpromazine and chlorpromazine sulfoxide.

Abstract

A method for the quantification of the effects of drugs upon the EEG and the EEG activating response using an Offner frequency analyser has been presented. The activating response has been shown to be graded in three respects: (1) latency of onset, (2) degree of depression of certain brain waves, and (3) degree of acceleration of frequency of certain brain waves. Using the degree of depression of activity of brain waves in the frequency range of 1.5 to 3.5 c.p.s. by graded stimuli to the midbrain reticular formation, it was possible to obtain estimates of the effect of drugs on the excitability and reactivity of the activating response. Simultaneous estimates of the excitability and reactivity of vasopressor responses to midbrain stimulation were obtained.