An hypothesis regarding the cortical mechanisms of operative memory

Investigations of the neuronal activity of the cerebral cortex of monkeys during the performance of a delayed spatial choice made it possible to formulate an hypothesis regarding the neuronal systems providing for operative memory. One system functions on the principle of relay race-reverberation transmission of information. During the action of a sensory signal a population of spatially selective "sensory" neurons is excited. By the delay period (operative memory) this information is transmitted to a population of "memory" neurons. The delay period is quantized in time segments in the course of which individual populations of cells are involved in relays in the reverberation activity. Each of these populations comprises a "neuronal trap" in which the excitation circulates for 1.5-2 sec. At the end of the delay period switching of the excitation to a different population of cells takes place, which are associated with the preparation of a goal-directed movement (the "neurons of the motor programs"). Another system of neurons assures the reliability of the transitional phases of the above-named processes, specifically: 1) of the switchings of information from the "sensory" neurons to the "memory" neurons and subsequently to the neurons of the "motor programs"; 2) the reflection of the entire period of operative memory without relay race-reverberation; and 3) the preservation of the signal information in the activity of a unified neuronal population right up to the moment of the performance of the goal-directed movement. The above-designated systems are represented variously in the associative (frontal and parietal) zones of the neocortex.