P237 Modulating executive functions and working memory performance on clinical neuropsychological tasks with theta burst transcranial magnetic stimulation

Abstract

Introduction Theta burst stimulation (TBS) protocols hold high promise in neuropsychological rehabilitation thanks to its ability to induce lasting effects on cortical excitability following a short delivery time. Nevertheless, its ability to inhibit (continuous protocol, cTBS) or facilitate (intermittent, iTBS) brain function from cortical areas other than the motor cortex remains to be fully established. The behavioral effects of TBS over the dorsolateral prefrontal cortex (DLPFC) are particularly interesting given its involvement in working memory and executive processing, often impaired after brain injury, and also due to its role of hub of frontal areas, for which it is frequently chosen as a target for treatment and rehabilitation. Objective To explore the ability of cTBS and iTBS to modulate working memory and executive functions assessed with clinical neuropsychological tasks. Materials and methods 36 healthy participants performed 3 clinical neuropsychological tasks: Digits Backward, Stroop test and Tower of Hanoi (Fig. 1). Subjects were assessed twice, first at baseline 1 week prior to stimulation and immediately following a single session of either active cTBS, active iTBS or sham TBS, delivered to the left DLPFC. Results Following sham TBS participants’ performance improved in the Stroop test, with higher scores in Color and Color-Word conditions, as well as lower interference scores (Fig. 2), likely caused by practice effects. Both, iTBS and cTBS, yielded improvements in the Digits Backward task and the Word score of the Stroop test. Moreover, similarly to the sham group, following iTBS participants showed lower Interference scores. In contrast, expected improvements in color score were not induced. Finally, cTBS decreased the number of movements necessary to complete the Tower of Hanoi. Nonetheless, at difference with the sham group, no improvements were observed in the Interference score of Stroop test. Conclusions TBS over DLPFC modulates working memory performance and executive processes. Both protocols resulted in similar working memory and information processing speed outcomes, whereas their effect on executive functions differed: cTBS impaired inhibitory control but improved planning abilities in a spatial task, meanwhile, no specific effects were observed following iTBS. Download : Download high-res image (431KB) Download : Download full-size image Download : Download high-res image (217KB) Download : Download full-size image