Impact of Prefrontal Theta Burst Stimulation on Clinical Neuropsychological Tasks

Abstract

Theta burst stimulation (TBS) protocols hold high promise in neuropsychological rehabilitation. Nevertheless, their ability to either decrease (continuous, cTBS) or increase (intermittent, iTBS) cortical excitability in areas other than the primary motor cortex, and their consistency modulating human behaviors with clinically relevant tasks remain to be fully established. The behavioral effects of TBS over the dorsolateral prefrontal cortex (dlPFC) are particularly interesting given its involvement in working memory (WM) and executive functions (EF), often impaired following frontal brain damage. We aimed to explore the ability of cTBS and iTBS to modulate WM and EF in healthy individuals, assessed with clinical neuropsychological tests (Digits Backward, 3-back task, Stroop Test, and Tower of Hanoi). To this end, 36 participants were assessed using the four tests 1 week prior to stimulation and immediately following a single session of either cTBS, iTBS, or sham TBS, delivered to the left dlPFC. No significant differences were found across stimulation conditions in any of the clinical tasks. Nonetheless, in some of them, active stimulation induced significant pre/post performance modulations, which were not found for the sham condition. More specifically, sham stimulation yielded improvements in the 3-back task and the Color, Color-Word, and Interference Score of the Stroop Test, an effect likely caused by task practice. Both, iTBS and cTBS, produced improvements in Digits Backward and impairments in 3-back task accuracy. Moreover, iTBS increased Interference Score in the Stroop Test in spite of the improved word reading and impaired color naming, whereas cTBS decreased the time required to complete the Tower of Hanoi. Differing from TBS outcomes reported for cortico-spinal measures on the primary motor cortex, our analyses did not reveal any of the expected performance differences across stimulation protocols. However, if one considers independently pre/post differences for each individual outcome measure and task, either one or both of the active protocols appeared to modulate WM and EF. We critically discuss the value, potential explanations, and some plausible interpretations for this set of subtle impacts of left dlPFC TBS in humans.

Impact of different intensities of intermittent theta burst stimulation on the cortical properties during TMS‐EEG and working memory performance

“…The reason for this discrepancy remains unclear, and further research is required as currently only a few studies have been performed in this area to date (Cheng et al, ; Debarnot et al, ; Demeter, Mirdamadi, Meehan, & Taylor, ; Hoy et al, ; Ryals, Rogers, Gross, Polnaszek, & Voss, ). A recent study investigated the effect of prefrontal TBS on a series of cognitive tasks, such as Digits Backward, 3‐back task, Stroop Colour and Word Test, and the Tower of Hanoi (Viejo‐Sobera et al, ). Only subtle behavioural changes were found in these measures in the absence of statistical differences between iTBS, cTBS and sham condition, and with no clear bi‐directional changes (i.e., enhanced or impaired performance following iTBS or cTBS, respectively).…”

The effects of individualised intermittent theta burst stimulation in the prefrontal cortex: A TMS‐EEG study

“…However, several studies with large sample sizes (n > 50) have found no group-level change in MEPs following 50 Hz iTBS (Hamada et al, 2013;Lopez-Alonso et al, 2014;Player, Taylor, Alonzo, & Loo, 2012). Similarly, prefrontal iTBS has shown an improvement in working memory in some studies Lowe et al, 2018), however, not in other studies (Chung, Rogasch, Hoy, Sullivan, et al, 2018b;Grossheinrich et al, 2009;Viejo-Sobera et al, 2017). Similarly, prefrontal iTBS has shown an improvement in working memory in some studies Lowe et al, 2018), however, not in other studies (Chung, Rogasch, Hoy, Sullivan, et al, 2018b;Grossheinrich et al, 2009;Viejo-Sobera et al, 2017).…”

“…Evidence suggests TBS over the prefrontal cortex may also modulate executive functioning in healthy individuals (Cho et al, 2010;Verbruggen, Aron, Stevens, & Chambers, 2010;Viejo-Sobera et al, 2017). Evidence suggests TBS over the prefrontal cortex may also modulate executive functioning in healthy individuals (Cho et al, 2010;Verbruggen, Aron, Stevens, & Chambers, 2010;Viejo-Sobera et al, 2017).…”

“…Increased interest in prefrontal application of TBS has also led to the investigation of associated cognitive processes. Evidence suggests TBS over the prefrontal cortex may also modulate executive functioning in healthy individuals (Cho et al, 2010;Verbruggen, Aron, Stevens, & Chambers, 2010;Viejo-Sobera et al, 2017). iTBS to the left prefrontal cortex has been shown to improve n-back task performances Viejo-Sobera et al, 2017), while cTBS had the opposite effect (Lee & D'Esposito, 2012;Schicktanz et al, 2015;Viejo-Sobera et al, 2017).…”

“…Evidence suggests TBS over the prefrontal cortex may also modulate executive functioning in healthy individuals (Cho et al, 2010;Verbruggen, Aron, Stevens, & Chambers, 2010;Viejo-Sobera et al, 2017). iTBS to the left prefrontal cortex has been shown to improve n-back task performances Viejo-Sobera et al, 2017), while cTBS had the opposite effect (Lee & D'Esposito, 2012;Schicktanz et al, 2015;Viejo-Sobera et al, 2017). Furthermore, a recent meta-analysis has demonstrated that the effectiveness of iTBS may be task-dependent and most reliable effects were observed in working memory paradigms (Lowe, Manocchio, Safati, & Hall, 2018).…”