Specificity of evoked cortical response as a function of arousal state

This study was undertaken to demonstrate that specific cortical response to a rhythmic stimulus would vary as a function of arousal level. Three levels of arousal were employed. The first consisted of a relaxed, resting state; in the second the subject placed his hand in a beaker of ice water, and in the third 1-1/2 grains of sodium amytal were taken. The first condition is "medium" arousal, the second "hig" arousal, and the third "low" arousal. In each of these three conditions, three treatments were employed in the following order: 10 seconds of no stimulus (silence), 10 seconds of photic stimulus at 15 cycles per second, then 10 seconds of sound stimulus (clicks) at 15 per second. It was predicted that the amount of 15 cycle per second activity on EEG recording would increase from treatment 1 to 2 and from 1 to 3. This was in fact demonstrated. It was further predicted that the specificity of cortical response to rhythmic stimulation, when compared to medum arousal condition, would break down under the two other experimentally imposed conidtions. This was not demonstrated. [...]