Repetitive transcranial magnetic stimulation (rTMS) of the dorsolateral prefrontal cortex reduces resting-state insula activity and modulates functional connectivity of the orbitofrontal cortex in cigarette smokers

Abstract

Background Previous studies reported that repetitive transcranial magnetic stimulation (rTMS) can reduce cue-elicited craving and decrease cigarette consumption in smokers. The mechanism of this effect however, remains unclear. We used resting-state functional magnetic resonance imaging (rsfMRI) to test the effect of rTMS in non-treatment seeking smokers. Methods We used a single blinded, sham-controlled, randomized counterbalanced crossover design where participants underwent two visits separated by at least 1 week. Participants received active rTMS over the left dorsolateral prefrontal cortex (DLPFC) during one of their visits, and sham rTMS during their other visit. They had two rsFMRI scans before and after each rTMS session. We used the same rTMS stimulation parameters as in a previous study (10 Hz, 5 seconds-on, 10 seconds-off, 100% resting motor threshold, 3000 pulses). Results Ten non-treatment-seeking, nicotine-dependent, cigarette smokers (6 women, an average age of 39.72 and an average cigarette per day of 17.30) finished the study. rsFMRI results demonstrate that as compared to a single session of sham rTMS, a single session of active rTMS inhibits brain activity in the right insula and thalamus in fractional amplitude of low frequency fluctuation (fALFF). For intrinsic brain connectivity comparisons, active TMS resulted in significantly decreased connectivity from the site of rTMS to the left orbitomedial prefrontal cortex. Conclusions This data suggests that one session of rTMS can reduce activity in the right insula and right thalamus as measured by fALFF. The data also demonstrates that rTMS can reduce rsFC between the left DLPFC and the medial orbitofrontal cortex.

Resting State Functional Connectivity Signature of Treatment Effects of Repetitive Transcranial Magnetic Stimulation in Mal de Debarquement Syndrome

“…Thus, it was suggested that the therapeutic mechanism of rTMS was to effectively normalize functional connectivity. The finding that TMS acts by modulating functional connectivity within cortical networks is corroborated by studies employing rTMS in depression (Kozel et al, 2011 ), essential tremor (Popa et al, 2013 ), stroke (Volz et al, 2016 ), and other behavior modification (Li et al, 2017 ). Our findings are consistent with these studies such that in MdDS, reduction of symptoms after rTMS treatment was associated with a decrease of RSFC, particularly between the EC and the default mode network.…”

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“…Eleven studies were conducted to investigate the use of rTMS on tobacco use disorder (nicotine dependence). Apart from Li et al, all studies demonstrated positive effects of rTMS, via reduction in nicotine cravings and/or overall cigarette consumption post‐active stimulation compared to baseline and sham data. Nine studies directed stimulation at either the left or the right DLPFC with a stimulation frequency of 1–20 Hz.…”

“…With respect to effects of brain stimulation observed between SUDs, commonalities between rTMS and tDCS emerged. Studies utilizing rTMS observed promising findings in trials conducted in nicotine or stimulant (cocaine, methamphetamine) dependent samples, with 10/11 and 5/7 positive studies, respectively in domains of craving and/or consumption. Moreover, in alcohol‐dependent participants, 6/9 studies suggested reductions in alcohol craving and/or consumption after active rTMS treatment.…”

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