TMS SMART – Scalp mapping of annoyance ratings and twitches caused by Transcranial Magnetic Stimulation

Abstract

The peripheral sensations and discomfort caused by TMS pulses significantly and systematically influence RTs during single-pulse, online TMS experiments.

Subjective Discomfort of TMS Predicts Reaction Times Differences in Published Studies

“…From these articles, we extracted all the locations stimulated (including any additional non-parietal or non-frontal/temporal areas) and the RTs associated with those locations, averaging across other conditions. These reported locations were matched as closely as possible with those stimulated in Meteyard and Holmes ( 2018 ), which mostly corresponded to 10–10 EEG electrode locations. As predictor variables, we used the mean of median rating of muscle twitches and the mean effect of TMS on RT (i.e., change in RT with TMS as compared to no TMS), which were extracted from http://www.tms-smart.info .…”

“…TMS can still be uncomfortable and painful, however, as it stimulates excitable superficial tissue including scalp muscles and peripheral nerves (Maizey et al, 2013 ). This causes annoyance, pain, and muscle twitches (i.e., discomfort) that vary systematically across the scalp (Meteyard and Holmes, 2018 ). While superior and posterior scalp locations are associated with almost no discomfort, inferior frontal and temporal locations are associated with significant discomfort.…”

“…Meteyard and Holmes ( 2018 ) found that participants' subjective ratings of the annoyance, pain, and muscle twitches caused by single pulse TMS was significantly and strongly correlated with changes in reaction time (RT) on two simple stimulus-response congruency tasks. Ratings of muscle twitches accounted for 43% of the variance in RT.…”

“…Where multiple TMS locations, groups, or experiments were reported, each study contributed multiple data points. RT differences and standardized RT differences (RT difference/pooled SD) were correlated with the per-location mean of median ratings of muscle twitches and effect of TMS on RT from Meteyard and Holmes ( 2018 ). 95% confidence intervals for r -values were obtained by bootstrapping over 10,000 iterations.…”

Quantitative assessment of pain threshold induced by a single-pulse transcranial magnetic stimulation

“…TMS also causes head and face muscles to contract and stimulates cutaneous fibers, which often leads to pain or discomfort on the scalp (Rossi et al, 2009;Wassermann, 1998;Rumi et al, 2005). This side-effect of TMS influences aspects of task performance such as accuracy and reaction time (Abler et al, 2005;Meteyard and Holmes, 2018), and to interfere with successful completion of experiments (Wassermann, 1998;Satow et al, 2002). Even though researchers have assessed the degree of pain and the area in which pain is perceived during TMS of certain intensities (Arana et al, 2008;Meteyard and Holmes, 2018), to our knowledge, no studies have quantitatively evaluated what TMS intensities actually cause pain (i.e., the pain threshold).…”