The Role of the Parahippocampal Cortex in Memory Encoding and Retrieval: An fMRI Study

A large number of studies have provided evidence of the parahippocampal cortex (PHC) activation during episodic memory which refers to two major processes that encoding and retrieval. To date, the differential role of PHC is involved memory encoding and retrieval remains unclear. We examined this issue in an fMRI study by measuring the brain activity of 36 normal subjects. The tasks consisted of encoding and retrieval two present forms of information (text and figure). At encoding, subjects were required to try to read and comprehend the meaning of the text or figure; at retrieval, they were asked to make judgments in regard to the content of reading comprehension. The direct comparison was between encoding and retrieval irrespective of text and figure that encoding was more significantly activated the left PHC (BA36) than retrieval; in contrast, retrieval was no significantly activated the PHC than encoding. The results suggest that the PHC is more involved in memory encoding. In addition, more significantly activated regions in PHC related to figure than text irrespective of encoding and retrieval indicates that the PHC more contributes to figure than text.