Role of the frontal lobes in integrative activity of the brain in Macaca mulatta.

Unit activity in the frontal cortex (s. principalis) during the performance of a complex behavior program--nonspecific expectation after a warning stimulus, conditioned stimulus, and delay period, trigger signal, and alternative choice, followed by food award--was studied by the multineuronal recording method. Processes of combination of external stimuli into an integrated program, retention of stimulus traces in the memory, and correct and incorrect problem solving were reflected in the unit activity of s. principalis. The level of the correct responses of choice and the corresponding correlates in modifications of unit activity depended directly on the level of food motivation. The results are discussed from the standpoint of the evolutionary formation of the thalamo-frontal association system of the brain, connected with the formation of behavior programs in accordance with current biological motivation.