Postural control is destabilized by theta-burst stimulation over the DLPFC during the performance of a concurrent working memory task

Human balance control requires the coordination of the human motor, cognitive, and sensory systems. Several studies have assessed the interaction between postural control and cognitive tasks when performed concurrently, but this interaction is yet to be fully understood. The current study aims to examine whether the postural control system is impacted by working memory, but more specifically by downregulating the Dorsal Lateral Prefrontal Cortex (DLPFC) during the performance of a working memory task using repetitive Transcranial magnetic stimulation (TMS). Additionally, this study aims to understand if there is a lateralization effect during TMS of the left vs right DLPFC, an area that is activated during the performance of working memory tasks. Postural sway of healthy young adults was recorded while participants performed a modified working memory task of varying difficulties across 3 blocks. The sessions were randomized to include continuous theta-burst transcranial magnetic stimulation of the left DLPFC, right DLPFC, or a sham condition. Our results showed that the performance of a cognitive task caused a destabilizing effect to occur in the postural control system, and with the introduction of TMS to the DLPFC, this effect was intensified. There was no difference between the left vs right stimulation of the DLPFC, but the overall effect seen shows that the cognitive and postural control systems rely on similar mechanisms that, when performed simultaneously, cause a negative interference effect.