A Working Memory Buffer in Parahippocampal Regions: Evidence from a Load Effect during the Delay Period

In this study, we tested the prediction that a putative WM buffer would demonstrate a load-dependent effect during a WM delay. Using high-resolution fMRI, we examined whether activity within the hippocampus (CA3/DG, CA1, and subiculum) and surrounding medial temporal cortices (PrC, EC, and parahippocampal cortex—PHC) is modulated in a load-dependent manner. We employed a delayed matching-to-sample task with novel scenes at 2 different WM loads. A contrast between high- and low-WM load showed greater activity within CA1 and subiculum during the encoding phase, and greater EC, PrC, and PHC activity during WM maintenance. These results are consistent with computational models and suggest that EC/PrC and PHC act as a WM buffer by actively maintaining novel information in a capacity-dependent manner.

Source: Cerebral Cortex - April 12, 2016 Category: Neurology Authors: Schon, K., Newmark, R. E., Ross, R. S., Stern, C. E. Tags: Articles Source Type: research