SINGLE UNIT PATTERNS DURING ANTICIPATORY BEHAVIOR

1. 1. Animals with several fine-wire electrodes implanted chronically in the brain for single unit recordings were pre-trained to immobilize themselves for brief intervals in order to obtain food or water. Unit activity was recorded simultaneously from 4 probes in each animal during these periods of immobilization and in other quiet intervals during wakefulness and sleep. Groups of from 7 to 20 probes were studied in each of the following areas: hippocampal, preoptic, lateral hypothalamic, ventral tegmental, thalamic, ventral reticular and dorsal reticular. 2. 2. Relatively large and stable changes in neuronal activity were noted in the course of the brief waiting periods. In dorsal reticular formation, thalamus and ventral tegmentum changes were regularly in the positive direction, neurons firing more rapidly as the reinforcing stimulus became more imminent. In the neuronal activity of hippocampus, preoptic area, ventral reticular. formation and hypothalamus, there was more variability between neurons; the firing rate would show either a decrement or on increment or no change depending on the particular unit involved. 3. 3. In individual experiments the activity of some neurons seemed to be especially related to either food or water behavior; these elements were more frequently found in the hippocampus, hypothalamus and preoptic area, the largest number appearing in area CA-3 of hippocampus. © 1969.