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A previous paper of ours (Begleiter, Gross, & Kissin, 1967) demonstrated that it was possible to condition affective meaning to meaningless figures (CS), and significantly alter visual evoked potential (VEP) amplitudes and latencies to them, without the S's awareness of the CS–UCS relationship (Experiment I, totally unaware). In the present study some Ss were deliberately informed that a CS–UCS connection existed; however, the exact nature of their relationship was not divulged (Experiment II, slightly aware). Other Ss were explicitly informed of the correct CS–UCS contingency, and entire conditioning paradigm (Experiment III, fully aware). One physiological (VEP) and two behavioral (interflash interval and semantic differential) indices of conditioning were obtained during an extinction procedure, and demonstrated significant differences between CRs in Experiment II, but none in Experiment III. VEP amplitudes to positive and negative CSs were enhanced in Experiment II, and suppressed in Experiment I, in comparison to the neutral CS. This effect was most marked in responses to the negative CS. It is suggested that level of awareness of the CS–UCS contingency might be reflected in our physiological index of conditioning - VEP amplitude.

It has been postulated that withdrawal from alcohol ingestion by alcoholics, is manifested by hyperexcitability of the central nervous system.

The effects of alcohol on the electrical activity of the brain have been studied in animals and in man. In a comprehensive review of the animal literature, Himwich and Callison (1972) reported that alcohol in adequate doses depresses the functions of the central nervous system. Begleiter and Platz (1972) reviewed the human literature and concluded that the effects of alcohol on human EEG appear primarily to be an increase in the total amount of alpha activity and as a slowing of its frequency.

Withdrawal has often been considered a phenomenon which occurs only after the cessation of long-term alcohol intake. The occurrence of withdrawal signs and symptoms upon cessation of alcohol ingestion is evidence of physiological dependence. It has also been postulated by Seevers and Deneau (1964) that physical dependence is characterized by hyperexcitability of the central nervous system. Consequently, we recently undertook to study changes in brain excitability of alcoholics, during alcoholization and withdrawal. We used the recovery function of somatosensory evoked potentials to assess changes in CNS excitability. Our findings (Begleiter, Porjesz and Yerre, in press) demonstrated that an increase of central nervous system excitability results from the cessation of alcohol intake, even after short periods of drinking. The state of hyperexcitability increases as drinking progresses and appears to reach a peak approximately 34 hours subsequent to withdrawal from prolonged alcohol ingestion. Three days after cessation of alcohol intake, our recovery function values return to normal. Our data support the hypothesis that partial withdrawal is manifested by a latent rebound hyperexcitability which occurs subsequent to depression of the central nervous system by alcohol.

The electrophysiological responses to a flash of medium intensity have different wave shapes in trials in which the occurrence of bright stimuli or dim stimuli is expected. When a bright or dim stimulus is signaled, the potentials evoked by the medium stimulus resemble the responses evoked by a real bright or dim flash.

THE ESTABLISHMENT of brainevoked potentials as a valid technique for tapping cerebral responses to specific stimuli has created frenzied attempts to relate it to many areas of research, not always appropriately. Many researchers have been investigating the possibility that the averaged evoked response might elucidate and differentiate mechanisms involved in psychopathology, and as a result, a wealth of evidence has been amassed relating various aspects of psychopathology to the cortical evoked response. In this paper, no attempt has been made to present an exhaustive review of the literature. Our purpose is to give a critical review of selected experiments from the current literature, attempting to integrate and compare them, and emphasizing the need for further controls in experimental design wherever necessary. In 1960 Shagass and Schwartz began to study evoked potentials in psychiatric patients, hoping to provide psychiatrically relevant