I. INTRODUCTION Anxiety is generally regarded as a problem of prime importance for clinical psychiatry. The literature is replete with descriptions of its subjective symptomatology and peripheral physiology, as well as its cultural and philosophical significance.* The fact that anxious patients characteristically show signs of restlessness, sympathetic overactivity, and resistance to sedation has led some authors to assume that anxiety is associated with an increased excitability of brain and thus with an increased susceptibility to seizures.† However, we are not aware of any reports on direct measurements of cortical excitability in anxiety. Therefore, the present study was designed to shed some light on the central physiology of anxiety by measuring variations in seizure threshold in hospitalized psychotic patients undergoing electroshock treatment (E. S. T.). Our own observations, previously reported in brief,14show that human anxiety is associated with an elevation of threshold to electrically induced seizures. Parallel studies on