Theta Burst Stimulation: Effects of the Posterior Superior Temporal Sulcus on Emotional Perception

Theta Burst Stimulation: Effects of the Posterior Superior Temporal Sulcus on Emotional Perception

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Abstract

A fluid source of information about another person's intents, emotions, and focus areas is their face. The neurological underpinning for all these abilities is the temporal lobe, one of the major cerebral cortex divisions.

The suggested study aims to evaluate the function of the posterior superior temporal sulcus in the perception of facial emotions utilising theta burst stimulation (TBS).

Theta Burst Stimulation: Effects of the Posterior Superior Temporal Sulcus on Emotional PerceptionIntroduction

Humans have a diverse range of social behaviours. We exhibit intricate cooperative behaviour, adaptability in our social reactions, and deftness in navigating vast social groups. These behaviours are made feasible by more fundamental cognitive skills like communication, facial recognition, storing and accessing social concept information, and emotion processing. The temporal lobe, one of the main divisions of the cerebral cortex, serves as the neurological foundation for all these skills (Deen et al., 2015). Faces serve as a dynamic source of information about the feelings, intentions, and focus areas of other people (Pitcher et al., 2017). One of the longest sulci in the brain is the posterior superior temporal sulcus (pSTS), which extends anteriorly from theparietal lobe and continues over the full length of the temporal lobe (Deen et al., 2015). The superior temporal sulcus (STS) is recognised as a focal area for social perception and cognition. This entails seeing people's expressions and movements as well as understanding their actions, emotions, and language (Deen et al., 2015). One area of social perception and cognition where subregions of the pSTS have been related is the perception of faces.

There is substantial proof that the pSTS is active when people are performing tasks that require them to process information about human faces, as shown by functional brain imaging techniques (e.g., fMRI and PET scans). Transcranial magnetic stimulation (TMS) has been widely employed to investigate the physiology and plasticity of the cortex. The term transcranial brain stimulation (TBS) refers to a variety of non-invasive methods aimed at modulating brain cortex activity using an external source, typically an electric or magnetic field (Chung et al., 2016). Techniques for non-invasive brain stimulation are frequently employed in both clinical and research contexts because of their capacity to cause brief alterations in cortical activity (Chung et al., 2016).

Although it has been hypothesised that the pSTS aids in interpreting human faces, this theory is still unclear. Deen et al. (2015) employed a conventional block-design functional magnetic resonance imaging (fMRI) method to look for functional specialisation within the pSTS. The response to several situations was measured in relation to the fixation baseline, and the responses in a few conditions were contrasted. In various studies, offline repeated transcranial magnetic stimulation (rTMS) to the pSTSwhere "offline" denotes that stimulation does not take place concurrently with the taskwas used to study how people perceive emotions (basil et al., 2017). As a result, "online" stimulation protocols deliver stimulation while the task is being performed. This means that stimulation happens at a specified point in the task protocol, generally with a single TMS pulse or a quick burst of high-frequency stimulation. Continuous theta burst stimulation (cTBS) may have advantages over repetitive transcranial magnetic stimulation (rTMS), including similar effect sizes to online stimulation, noticeably shorter stimulation times, and longer effect durations (Basil et al., 2017).

Although Deen et al. (2015) study makes progress in our understanding of pSTS, it is still unknown how much of the functional characteristics of pSTS will be included in the expanded face processing system and how much this will add to the discussion of pSTS and emotion recognition. The purpose of the proposed study is to investigate, using theta burst stimulation (TBS), the role of the right pSTS in the perception of facial emotions, specifically the happiness. The intended candidates are adults aged 18 and over. It is hypothesised that participants FINISH THIS

Method

An a-priori power analysis performed in G*Power (Faul et al., 2007) for a repeated measures design indicated that a total sample size of 46 patients is required to detect a moderately sized effect (f = .25), with = .05 and power = .90. Those who have a history of seizures, people who have metal in their head, and any implanted devices are all to be excluded from the study. The precise placement of the right pSTS is adjusted for individual variances using magnetic resonance imaging (MRI) guided neuro-navigation of the TMS coil.

Participants will have to determine if two faces belonging to separate people had the same expression when completing the facial expression matching test. The five images from the same model displaying the five different emotions will serve as the stimuli for the expression matching task. Each image will be cropped using the same contour and limited to showing only the area from the chin up (for an example, see Figure 1). This activity will be used to mitigate any non-TMS effects that might arise from variations in the somatosensory sense of stimulation at the different sites.

Figure SEQ Figure * ARABIC 1 From "FSTC: Face stimulus and tool collection", by Stolier, R, n.d. (https://rystoli.github.io/FSTC.html).

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