Brain Potentials Provide Insights Into the Role of Prefrontal Cortex in Long-term Memory Retrieval

Three experiments were performed to examine contributions of prefrontal cortex to long-term memory retrieval in humans. In Experiment 1, electrical activity was recorded from the brain during an episodic retrieval task (retrieval of autobiographical memories) and during a semantic retrieval task (category-exemplar naming). Novel sounds presented intermittently during memory retrieval elicited a brain potential identifiable as the P3a potential. Predictions based on prior findings linking P3a with prefrontal cortex were that P3a amplitude would be reduced in proportion to the level of interference between novelty detection and memory retrieval. Relative to a condition in which participants attended to the sounds, P3a amplitudes were reduced during episodic retrieval, particularly at right lateral frontal scalp locations. A similar but less lateralized pattern of frontal P3a reduction was observed during semantic retrieval. These findings support the notion that right prefrontal cortex contributes to long-term memory retrieval, particularly for episodic memories.