Relationship Between Brain Potentials and Some Other Physiological Variables

Abstract

Most prominent in the records of the electrical activity from the brain in intact human subjects are large and fairly rhythmic oscillations of potential called alpha waves. In a recent study of brain potentials in children and adults by Lindsley 1 the average frequency of the alpha rhythm in 54 adults was found to be 10.4 per second with a range of variation from 8 to 12 per second. Under normal conditions the frequency for any one individual was remarkably constant, often varying by less than 1 cycle per second over a period of months and only occasionally by as much as 2 cycles per second. In children the rhythmic alpha waves first appeared at about 3 months of age and at a frequency of 3 to 4 per second. The frequency increased with age until the adult average was reached at 8 to 10 years of age. A slight rise in frequency above the adult level occurred between 10 to 12 years of age.

The present study is concerned mainly with the frequency variations observed in adults, since the various processes of growth and development make difficult certain comparisons in children. An attempt has been made to determine the relationship between the frequency of the alpha waves and some other physiological variables such as metabolic rate, heart rate, blood pressure, rectal temperature and respiration.

Thirteen adults, 12 women and 1 man, were used as subjects. Of these, 4 women medical students ranging in age from 21 to 31 years were studied every morning for 32 or 34 consecutive days. All records were obtained early in the morning under basal conditions. Rectal temperatures were taken by the women on awakening and before getting out of bed.