Behavioural and neurophysiological effects of continuous theta-burst stimulation to the right superior temporal sulcus

<h2>Abstract</h2> Facial emotion processing (FEP) is vital for social interactions and fostering positive, healthy relationships. The posterior portion of the right superior temporal sulcus (pSTS) is particularly involved in FEP and has been implicated in conditions characterised by FEP difficulties such as autism spectrum disorder (autism). The present research used a double-blind, repeated measures (crossover), sham-controlled design to test the causal role of the right pSTS in FEP using continuous theta-burst stimulation (cTBS). Nineteen right-handed, English-speaking, neurotypical adults aged 18-24 years (Mean = 20.42, Standard Deviation=1.80; biological sex: 12 females, 7 males) received a single session of either active or sham cTBS over the right pSTS. Participants completed a neutral face recognition task and an emotional face recognition task while their brain activity was recorded using electroencephalography (EEG). We measured the face-sensitive N170 event-related potential (ERP) over the right and left pSTS, and over the medial prefrontal cortex using EEG. N170 amplitudes were larger in response to fearful and happy faces compared to neutral faces; however, cTBS did not modulate accuracy, reaction time, or N170 amplitude in response to neutral or emotional faces. The present research could not confirm a causal role of the right pSTS in FEP. The variability in response to cTBS, and the small sample size utilised in the present research may attribute to these null findings. This research may inform future efforts seeking to understand FEP in neurotypical and clinical cohorts.