Theta burst stimulation (TBS) over DLPFC enhances executive functions in depressed patients

Background and Aim : Executive function includes many skills such as self-monitoring, task monitoring, inhibition, shift, emotional control, initiation, planning organizing, working memory. Executive function disorder is not a specific, standalone diagnosis or condition. Instead neurological, mental health and behavioral disorder, such as depression can affect a person’s executive function. the Dorso-Lateral Prefrontal cortex exhibits decreased connectivity with the dorsal anterior cingulate in depressed elderly and is a key in orchestration of executive function. A newer form of rTMS protocol , Theta burst stimulation (TBS) is a highly efficient repetitive transcranial magnetic stimulation (rTMS) variant employed in experimental and clinical treatment paradigms. TBS involves pulses being applied in bursts of three at high frequency (50hz) with an inter burst interval of 200ms (5hz, which is in the range of theta frequency). In cTBS Either 300 pulses (20s) or 600 pulses (40s) of TBS are delivered without any interruption. This paradigm reduces cortical excitability beyond its stimulation duration by approximately 20 min for 300 pulses of cTBS and up to 1 hr for 600 pulses of cTBS. In iTBS ,2s of TBS trains (30pulses) are repeated every 10 s for 190s, with a total number of 600 pulses. TBS over DLPFC modulates working memory performance and executive processes.Methods : This article is a review of published articles regarding Theta burst stimulation over DLPFC and executive functions in depressed patients.Results : The role of the executive function in the human left dorsolateral prefrontal cortex (LDLPFC) was explored using transcranial magnetic stimulation (TMS) after confirming the LDLPFC activation using fMRI. researches have explored the ability of cTBS and iTBS to modulate working memory and executive functions. 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. The iTBS paradigm was effective in improving mood and executive function in older adults. Both the psychometric measure and the self-reported executive function measure (indicative of dysexecutive behavior) reflected improvements post iTBS. Improvement in executive function was correlated with depression improvementConclusion : TBS protocol have a major advantage over standard rTMS approaches in their reduced administration duration. 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.

کلیدواژه ها:

transcranial magnetic stimulation ، Theta burst stimulation ، Dorsolateral prefrontal cortex ، DLPFC ، executive function ، depression