Poster D124, Monday, March 26, 8:00-10:00 am, Exhibit Hall C
Dissociable cortico-hippocampal networks during the processing of time and space information in episodic encoding
Saeko Iwata1, Hikaru Sugimoto1,2, Takashi Tsukiura1; 1Graduate School of Human and Environmental Studies, Kyoto University, 2Japan Society for the Promotion of Science
Episodic memory is defined as memory for personally experienced events with time and space contexts. Previous studies have demonstrated that a temporal context processed in the lateral prefrontal cortices (lPFC) and a spatial context processed in the parahippocampal (PHC) and retrosplenial cortices (RSC) are integrated in the hippocampus during episodic remembering. However, little is known about the functional dissociation in the cortico-hippocampal networks underlying the processing of time and space information during episodic encoding. To investigate this issue, we scanned 42 healthy young adults to investigate neural activation by fMRI during the encoding of pictures, and then performed the picture retrieval task outside fMRI. During encoding, participants were presented with scene pictures, and judged how close the time in each picture was to the time when participants were performing this task (Time), how close the landscape in each picture was to a landscape of the place where participants were performing this task (Place), and the location of a dot in each corner of the pictures (Control). During retrieval, participants made old-new judgments for target and distracter pictures. In fMRI results, the lPFC showed significantly greater activation in Time, and PHC and RSC activation significantly increased in Place. The gPPI analyses revealed that activation in the lPFC, RSC and PHC was functionally connected with that in the hippocampus, but regions reflecting the functional connectivity were dissociable between Time and Place within the hippocampus. These findings suggest that temporal and spatial contexts in episodic memories could be represented in different cortico-hippocampal networks.
Topic Area: LONG-TERM MEMORY: Episodic