Modulating vicarious tactile perception with transcranial electrical current stimulation.

Natalie C Bowling,Michael J Banissy

doi:10.1111/ejn.13699

Natalie C Bowling, Michael J Banissy

Open Access

https://doi.org/10.1111/ejn.13699

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Abstract

Our capacity to share the experiences of others is a critical part of social behaviour. One process thought to be important for this is vicarious perception. Passively viewing touch activates some of the same network of brain regions as the direct experience of touch. This vicarious experience is usually implicit, but for some people, viewing touch evokes conscious tactile sensations (mirror‐touch synaesthesia). Recent work has attempted to induce conscious vicarious touch in those that do not normally experience these sensations, using transcranial direct current stimulation (tDCS). Anodal tDCS applied to primary somatosensory cortex (SI) was found to induce behavioural performance akin to mirror‐touch synaesthesia on a visuotactile interference task. Here, we conducted two experiments that sought to replicate and extend these findings by examining: (i) the effects of tDCS and high‐frequency transcranial random noise stimulation (tRNS) targeted at SI and temporo‐parietal junction (TPJ) on vicarious tactile perception, (ii) the extent to which any stimulation effects were specific to viewing touch to humans vs. inanimate agents and (iii) the influence of visual perspective (viewing touch from one's own vs. another's perspective) on vicarious perception. In Experiment 1, tRNS targeted at SI did not modulate vicarious perception. In Experiment 2, tDCS targeted at SI, but not TPJ, resulted in some modulation of vicarious perception, but there were important caveats to this effect. Implications regarding mechanisms of vicarious perception are discussed. Collectively, the findings do not provide convincing evidence for the potential to modulate vicarious tactile perception with transcranial electrical current stimulation.

Highlights

Representing and understanding others’ experiences is crucial to facilitate social interactions and build interpersonal relationships
We examined the impact of transcranial random noise stimulation (tRNS) targeted at bilateral primary somatosensory cortices (SI), and in another, we examine the effects of transcranial direct current stimulation (tDCS) (Experiment 2) targeted at right somatosensory cortex and the right temporo-parietal junction
Questionnaire of Mirror-Touch Synaesthesia (QMTS; from Bolognini et al, 2013): each participants’ experience during the Experiment 1: Effects of high-frequency tRNS targeted at bilateral somatosensory cortex on vicarious tactile perception

Summary

Introduction

Representing and understanding others’ experiences is crucial to facilitate social interactions and build interpersonal relationships. No study has examined if high-frequency tRNS might be useful to modulate vicarious perception, but given that in some circumstances bilateral somatosensory cortex activity is likely to contribute to perceiving touch to other people, this technique may offer a useful approach to examine the effect of increasing bilateral cortical excitability in the somatosensory cortices on tactile perception With this in mind, in addition to re-examining prior effects suggesting that tDCS targeted at the somatosensory cortex on the contralateral side to observed touch can induce MTS in non-synaesthetes, we sought to examine whether high-frequency tRNS targeted at bilateral somatosensory cortices would have similar effects. Based on prior research, increasing cortical excitability in somatosensory brain regions was expected to increase vicarious tactile perception when viewing another person being touched

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