The non-transcranial TMS-evoked potential is an inherent source of ambiguity in TMS-EEG studies
By Virginia Conde, Leo Tomasevic, Irina Akopian, Konrad Stanek, Guilherme B. Saturnino, Axel Thielscher, Til Ole Bergmann, Hartwig Roman Siebner. bioRxiv, 2018
314 citations recorded by the source corpus.
Transcranial Magnetic Stimulation (TMS) excites populations of neurons in the stimulated cortex, and the resulting activation may spread to connected brain regions. The distributed cortical response can be recorded with electroencephalography (EEG). Since TMS also stimulates peripheral sensory and motor axons and generates a loud “click” sound, the TMS-evoked EEG potential (TEP) not only reflects neural activity induced by transcranial neuronal excitation but also neural activity reflecting somatosensory and auditory processing. In 17 healthy young individuals, we systematically assessed the contribution of multisensory peripheral stimulation to TEPs using a TMS-compatible EEG system. Real TMS was delivered with a figure-of-eight coil over the left para-median posterior parietal cortex or superior frontal gyrus with the coil being oriented perpendicularly or in parallel to the target gyrus. We also recorded the EEG responses evoked by sham stimulation over the posterior parietal and superior frontal cortex, mimicking the auditory and somatosensory sensations evoked by real TMS. We applied state-of-the-art procedures to attenuate somatosensory and auditory confounds during real TMS, including the placement of a foam layer underneath the coil and auditory noise masking. Despite these precautions, the temporal and spatial features of the cortical potentials evoked by real TMS at the prefrontal and parietal site closely resembled the cortical potentials evoked by realistic sham TMS, both for early and late TEP components. Our findings stress the need to include a peripheral multisensory control stimulation in the study design to enable a dissociation between truly transcranial and non-transcranial components of TEPs.
Subfields: Cognitive Neuroscience, Neurology
View Paper: https://www.semanticscholar.org/paper/1dd12ba31abdcf677eaf558945da6f18aa07fa32
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Citations in the corpus
- Cell type-specific excitability probed by optogenetic stimulation depends on the phase of the alpha oscillation (2022, background): “Yet, given the number of confounding variables [17-19], the 50 neuronal basis of such phasic gating of stimulation pulses remains poorly understood.”
- Inferring Causality from Noninvasive Brain Stimulation in Cognitive Neuroscience (2020, unknown): “…beneath the coil to attenuate vibration, a TMS coil discharging at an ineffective distance to control for residual auditory input, and individually adjusted electric stimulation of the skin via surface electrodes beneath the TMS coil to mimic peripheral nerve stimulation (Conde et al., 2019).”