The baseline transcephalic D.C. potential in normals

This study, employing six groups of non-psychotic, unmedicated male subjects, ranging from six to sixty in number in each group, replicates and expands on previous work concerning the effects of a number of variables on the initial baseline transcephalic d.c. potential (IP) and the baseline d.c. shift (δP) after a 10-min test period involving the subjects in performing mental tasks. In agreement with prior studies, the range of IP was found to be from -25·0 to + 30·0 mV and appears to be unaffected by age or intelligence. Anxiety increases the variance of the group tested. Subjects tend to be most negative around 3:00 p.m. to 5:00 p.m. and 2–3 hr after eating. Heavy eaters show a decreased -δP in response to novel stimuli, faecal retainers show a more positive IP and a more negative δP, and mild urinary retention increases the variance of the IP. Subjects with an allergic history show a general increase of both negative IP and δP. A 20-min waiting period abolishes any effect of nicotine inhalation. The greatest stimulus to promote a -δP is one requiring the subject to develop a new and complex orientation in order to respond to a task.