Abstract
Working memory is important for a wide range of high-level cognitive activities. Previous studies have shown that the dorsal lateral prefrontal cortex (DLPFC) plays a critical role in working memory and that behavioral training of working memory can alter the activity of DLPFC. However, it is unclear whether the activation in the DLPFC can be self-regulated and whether any self-regulation can affect working memory behavior. The recently emerged real-time functional magnetic resonance imaging (rtfMRI) technique enables the individuals to acquire self-control of localized brain activation, potentially inducing desirable behavioral changes. In the present study, we employed the rtfMRI technique to train subjects to up-regulate the activation in the left DLPFC, which is linked to verbal working memory. After two rtfMRI training sessions, activation in the left DLPFC was significantly increased, whereas the control group that received sham feedback did not show any increase in DLPFC activation. Pre- and post-training behavioral tests indicated that performance of the digit span and letter memory task was significantly improved in the experimental group. Between-group comparison of behavioral changes showed that the increase of digit span in the experimental group was significantly greater than that in the control group. These findings provide preliminary evidence that working memory performance can be improved through learned regulation of activation in associated brain regions using rtfMRI.
Highlights
Working memory involves the temporary storage and manipulation of information that is assumed to be necessary for a wide range of complex cognitive activities such as reasoning, comprehension and learning [1]
We aimed to explore whether activation in the dorsal lateral prefrontal cortex (DLPFC) can be self-regulated through real-time functional magnetic resonance imaging (rtfMRI) training and, if so, whether successful up-regulation of activation in the DLPFC can lead to an improvement in working memory behavior
One-sample t-tests on the region of interest (ROI) localizer run data for the two groups together showed that the digital 3-back task significantly activated the bilateral DLPFC, supplement motor area (SMA), bilateral premotor area (PMA), left inferior frontal gyrus (IFG), bilateral posterior parietal cortex (PPC), bilateral insular, caudate, putamen, thalamus and cerebellum
Summary
Working memory involves the temporary storage and manipulation of information that is assumed to be necessary for a wide range of complex cognitive activities such as reasoning, comprehension and learning [1]. According to a multicomponent model proposed by Baddeley and Hitch, working memory could be divided into an attention control system, the central executive, and two modality-based temporary storage systems, the phonological loop and the visuospatial sketch pad. The central executive system controls attention and information flows to and from the phonological loop and visuospatial sketch pad, which separately buffer the verbal-acoustic and visual material [2]. Funahashi et al used a spatial working memory task to explore the prefrontal cortex of monkeys and the result of single-unit recording showed that the DLPFC controlled information maintenance [7]. By examining the activation of the human prefrontal cortex as verbal and spatial working memory tasks were performed simultaneously, D’ Esposito et al identified the key role of the DLPFC in coordinating two concurrent tasks [8]. To further determine the functional importance of the DLPFC in working memory, Barbey et al
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