Abstract
A plethora of previous studies, including monkey electrophysiology and human neuroimaging, have suggested that frontoparietal regions are activated during spatial working memory (WM) tasks (Smith & Jonides, 1999). Here we aimed to identify correlations between grey matter volume and spatial WM capacity estimates in healthy young adults. We performed voxel-based morphometry on the structural MRI data of 48 young healthy volunteers to obtain measures of grey matter volume. Behavioral capacity estimates of spatial WM were obtained using a staircase method (3-up-1-down starting at 2 locations) that varied the number of locations in the memory set of a delayed-response WM task. Participants were presented with a memory set containing irregular shapes (1.5°×1.5°) that appeared for 100 ms each at peripheral locations arranged in a circle around fixation (3° from fixation). Participants maintained the location (and ignored the shape) of the memory set items. Following a 1 sec delay, a memory probe was presented for up to 3 sec that matched the location of one of the memory set items in 50% of the trials. Participants made a button press to indicate whether the memory probe matched any of the memory set locations. A multiple regression analysis using SPM8 was performed to identify cortical regions with a significant correlation with individuals' spatial WM capacity. We observed positive correlations between individual spatial WM capacity estimates and grey matter density in bilateral inferior parietal lobule (IPL) and right middle frontal gyrus (MFG). Our findings are consistent with previous work showing that these brain areas are consistently recruited during the maintenance of spatial information (Wager & Smith, 2003; Leung, Gore & Goldman-Rakic, 1999), further indicating that people with higher grey matter density in IPL and right MFG are able to maintain a greater amount of spatial information in WM.
Meeting abstract presented at VSS 2013