The Contribution of the Dorsolateral Prefrontal Cortex in Full and Divided Encoding: A Paired-Pulse Transcranial Magnetic Stimulation Study

Sophie Blanchet,Cyril Schneider,Geneviève Gagnon

doi:10.1155/2010/928436

Abstract

This research investigated the contribution of the dorsolateral prefrontal cortex (DLPFC) in the attentional resources in episodic encoding for both verbal and non-verbal material. Paired-pulse transcranial magnetic stimulations (TMS) were used to interfere transiently with either the left or right DLPFC during encoding under full attention (FA) or under divided attention (DA) in a recognition paradigm using words and random shapes. Participants recognized fewer items after TMS over the left DLPFC than over the right DLPFC during FA encoding. However, TMS over the left DLPFC did not impair performance when compared to sham condition. Conversely, participants produced fewer items after TMS over the right DLPFC in DA encoding compared to sham condition, but not compared to TMS over the left DLPFC. These effects were found for both words and random shapes. These results suggest that the right DLPFC play an important role in successful encoding with a concomitant task regardless of the type of material.

Highlights

Episodic memory allows an individual to remember the temporal and spatial context of events [29]
The present study aimed to investigate the involvement of the dorsolateral PFC (DLPFC) in the attentional resources during encoding according to the type of material
We found that transcranial magnetic stimulations (TMS) over the left DLPFC during encoding under full attention (FA) decreased hit percent when compared to TMS over the right DLPFC, for both random shapes and words

Summary

Introduction

Episodic memory allows an individual to remember the temporal and spatial context of events [29]. Successful encoding into episodic memory depends on the availability of attentional resources. Divided attention (DA) during encoding has a detrimental effect on subsequent recall performance in healthy young individuals [2,14,22]. Left PFC is often activated in episodic encoding under FA regardless of the type of material (see [12] for a review). The dorsolateral PFC (DLPFC) subareas have been reported to be sensitive to the DA detrimental effect during encoding. The previous findings rely on neuroimaging data, which use hemodynamic and metabolic indices.

Methods

Results

Conclusion