Bilateral activation of the prefrontal cortex after strategic semantic cognitive training

Abstract

The prefrontal cortex (PFC) has been implicated in the ability to apply semantic organizational strategies during verbal encoding and episodic learning. However, there has been no direct evidence demonstrating which specific areas in the PFC are engaged after cognitive training using semantic organizational strategies in healthy adult human subjects. In this study, we investigated the effects of semantic strategic training on brain activity and changes in behavioral performance, after cognitive training, using functional MRI (fMRI). There was a significant activation in bilateral dorsolateral prefrontal (DLPF) and orbitofrontal (OFC) areas after cognitive training. These results demonstrate the engagement of bilateral DLPF and OFC cortex during strategic memory processes, particularly when mobilization and effort of effective use of strategies are required. The functional adaptations observed here may also shed light on some of the processes underlying recovery with cognitive rehabilitation in patient populations with brain injury.

Brain regions supporting verbal memory improvement in healthy older subjects

“…In addition, participants recalled more words after the directed instructions for the SR condition and there was a significant correlation between semantic strategy scores and words recalled for the SR condition, a condition where this strategy can be used. These findings are similar to the ones found in healthy adult subjects 19 and other studies using different cognitive training in elderly subjects 21,22 and show that after a brief period of practice to apply efficient strategies older subjects can substantially improve their memory performance.…”

“…These findings are in line with studies of healthy older subjects employing longer periods of cognitive training showing increased activity after training in bilateral prefrontal regions including the inferior and medial frontal gyrus 21,23,25 . Previous results suggested that the left middle and inferior frontal gyrus and cerebellum support young adults' verbal encoding strategies 19,27 . In addition, there was greater activity in the right medial superior frontal gyrus and anterior cingulate.…”

“…The current paradigm was based on the California Verbal Learning Test (CVLT) 26 and validated in healthy adults and patients with brain lesions using fMRI 19,27 . For the UR condition, the words presented were not semantically related making it difficult to apply the semantic organizational strategies.…”

“…The left inferior prefrontal cortex (IPFC) mediates semantic processing of information 17,18 . The dorsolateral prefrontal cortex (DLPFC) supports updating, sequencing, and monitoring operations, all features of working memory, along with attention 19 . The orbitofrontal cortex (OFC) plays an important role in initiating relevant behavior, suppressing irrelevant responses and in the early mobilization of efficient strategies in novel situations 20 .…”

The basal ganglia circuits, dopamine, and ambiguous word processing: A neurobiological account of priming studies in Parkinson's disease

“…They proposed that the DLPFC was more directly involved in maintaining information relevant to response selection and execution at retrieval. Miotto et al (2006) investigated semantic organizational strategy application after cognitive training and found bilateral DLPFC and orbitofrontal cortex activation after training. It is difficult to evaluate the studies of Chan et al (2004) and Rodd et al (2005) against the requirements for working memory or semantic strategy application given that these tasks did not explicitly test for these effects.…”