Dual-site TMS demonstrates causal functional connectivity between the left and right posterior temporal sulci during facial expression recognition

Abstract

Background: Neuroimaging studies suggest that facial expression recognition is processed in the bilateral posterior superior temporal sulcus (pSTS). Our recent repetitive transcranial magnetic stimulation (rTMS) study demonstrates that the bilateral pSTS is causally involved in expression recognition, although involvement of the right pSTS is greater than involvement of the left pSTS. Objective: /Hypothesis: In this study, we used a dual-site TMS to investigate whether the left pSTS is functionally connected to the right pSTS during expression recognition. We predicted that if this connection exists, simultaneous TMS disruption of the bilateral pSTS would impair expression recognition to a greater extent than unilateral stimulation of the right pSTS alone. Methods: Participants attended two TMS sessions. In Session 1, participants performed an expression recognition task while rTMS was delivered to the face-sensitive right pSTS (experimental site), objectsensitive right lateral occipital complex (control site) or no rTMS was delivered (behavioural control). In Session 2, the same experimental design was used, except that continuous theta-burst stimulation (cTBS) was delivered to the left pSTS immediately before behavioural testing commenced. Session order was counter-balanced across participants. Results: In Session 1, rTMS to the rpSTS impaired performance accuracy compared to the control conditions. Crucially in Session 2, the size of this impairment effect doubled after cTBS was delivered to the left pSTS. Conclusions: Our results provide evidence for a causal functional connection between the left and right pSTS during expression recognition. In addition, this study further demonstrates the utility of the dualsite TMS for investigating causal functional links between brain regions.

Measuring the response to visually presented faces in the human lateral prefrontal cortex

“…Results demonstrated that the connectivity between the lateral prefrontal cortex and the pSTS was greater than between other face processing nodes. This is consistent with studies demonstrating that the pSTS preferentially processes dynamic facial aspects (Fox et al, 2009; Pitcher et al, 2019; Puce et al, 1998) and facial expressions (LaBar et al, 2003; Phillips et al, 1998; Sliwinska, Elson, et al, 2020; Winston et al, 2004). In addition, a study that assessed damage to the arcuate fasciculus (a white matter tract that connects the lateral temporal lobe with the inferior frontal lobe) reported behavioural impairments in face based mentalising tasks (Nakajima et al, 2018).…”

Synchronous facial action binds dynamic facial features

“…Lateralisation of the synchrony effect to the right field, and by implication to the left hemisphere, suggests a link to facial speech perception 39 , 40 . The processing of facial expression can be disrupted by TMS delivered to left and right 41 , 42 STS, and comparisons between moving faces and static faces tend to show activation in the right pSTS 23 , 43 . There is, however, recent evidence of greater activation in the left pSTS for speech-based expressions 23 and an area in the left hemisphere designated the Temporal Visual Speech Area ventral and posterior to pSTS has similarly been identified as specialised for visual speech 40 , 44 , 45 .…”

Face learning via brief real-world social interactions induces changes in face-selective brain areas and hippocampus

“…Movies of bodies, scenes, and scrambled objects were not relevant to this study hence their data are not presented. These stimuli have been successfully used for functional localisation of face-responsive areas in prior studies ( Handwerker et al, 2020 ; Sliwinska, Bearpark, et al, 2020 ; Sliwinska, Elson, et al, 2020 ; Sliwinska & Pitcher, 2018 ). There were 60 movie clips for each category in which distinct exemplars appeared multiple times.…”