Plasticity and memory in the prefrontal cortex.

Neuropsychological and neuroimaging studies in humans have shown that the prefrontal cortex (PFC) is involved in long-term memory functioning. In general, the participation of the PFC in long-term memory has been attributed to its role in executive control rather than information storage. Accumulating data from recent animal studies, however, suggest the possible role of the PFC in the storage of long-term memory. In support of this view, there is evidence that various projection systems in the PFC support long-term synaptic plasticity. Recording studies have further demonstrated neural correlates of learning in various animal species. Lastly, behavioral and physiological studies indicate that the PFC is critically involved in memory consolidation, retrieval and extinction processes. These studies then suggest that the PFC is an integral part of the neural network where long-term memory trace is stored and retrieved. Though decisive evidence is still lacking at present, we propose here to assign a term 'control memory' (i.e., memory for top-down control processes) as a new type of memory function for the PFC. This new principle of PFC-long-term memory can help organize existing data and provide novel insights into future empirical studies.