A preliminary study of dynamic neurochemical changes in the dorsolateral
prefrontal cortex during working memory
Working memory (WM) is one of the fundamental cognitive functions
associated with the dorsolateral prefrontal cortex (DLPFC). However, we
still know little about the neurochemical mechanisms of WM in the DLPFC.
Here, we investigated WM-related dynamic neurometabolite and hemodynamic
responses in the DLPFC. We measured Glx (glutamate+glutamine) and GABA
alterations as well as blood-oxygen-level-dependent (BOLD) signal
changes during a WM task combining functional magnetic resonance
spectroscopy and functional magnetic resonance imaging (fMRI). In the
DLPFC, we found that a 2-back task increased Glx concentrations and
larger BOLD signal changes, and that these task-modulated Glx increases
were positively correlated with task-induced regional activity.
Importantly, task induced Glx changes in the DLPFC were associated with
individual WM performance. Higher Glx increases were associated with
increased DLPFC activation and lower WM task performance in the
individuals. There were no changes in DLPFC GABA levels during WM
processing. Our findings suggest that glutamatergic modulation in the
DLPFC may play a critical role in WM processing and its performance.