The mid-ventrolateral prefrontal cortex and active mnemonic retrieval.

The role of the mid-ventrolateral prefrontal cortex in memory retrieval is examined and compared with the role of the mid-dorsolateral prefrontal cortex in the monitoring of information in memory. It has been argued that the mid-ventrolateral prefrontal cortex (areas 47/12 and 45) is involved in the active retrieval of information from posterior cortical association areas. Active retrieval is required when stimuli in memory do not bear stable relations to each other and therefore retrieval cannot be automatically driven by strong, stable, and unambiguous stimulus or context relations. Data from functional activation studies with normal human subjects are presented that have demonstrated specific changes in activity within the mid-ventrolateral region of the frontal cortex in relation to the active retrieval of information from memory. By contrast, increases in activity in the mid-dorsolateral region of the frontal cortex occur when the performance of the tasks requires monitoring of information in memory.