Prefrontal cortex in long-term memory: an “interference” approach using magnetic stimulation.

Neuroimaging has consistently shown engagement of the prefrontal cortex during episodic memory
tasks, but the functional relevance of this metabolic/hemodynamic activation in memory processing
is still to be determined. We used repetitive transcranial magnetic stimulation (rTMS) to transiently
interfere with either left or right prefrontal brain activity during the encoding or retrieval of pictures
showing complex scenes. We found that the right dorsolateral prefrontal cortex (DLPFC) was crucial
for the retrieval of the encoded pictorial information, whereas the left DLPFC was involved in encoding
operations. This ‘interference’ approach allowed us to establish whether a cortical area activated
by a memory task actually contributes to behavioral performance.