Towards a general semantics account of social cognition

: neuroimaging and neurostimulation evidence

Abstract

Social cognition is essential for effective social interactions, and its breakdown has profound consequences for an individual’s ability to function in society. To this end, social neurosciences have strived to develop a full account of the cognitive and brain basis of social cognition. However, a key remaining challenge is to elucidate whether brain regions are specialised for distinct social domains or whether they are supported by brain regions involved in more domain-general processes. With a focus on semantic cognition, the overarching question in this thesis asked about the degree to which social cognition implicates the same brain regions as semantic cognition and about the nature of their contribution. Accordingly, the principal aim of the empirical work outlined in this thesis is to present novel evidence regarding the neurobiological underpinnings of social processing. To achieve this, the research described in this thesis made use of three complementary neuroimaging approaches; functional magnetic resonance imaging (fMRI), large-scale neuroimaging meta-analysis and transcranial magnetic stimulation (TMS). The general Chapters 1 and 2 offer a broader introduction to the theoretical underpinnings of the topic and to the methodological considerations made in the empirical chapters. The focus in empirical Chapter 3 is on the role of the anterior temporal lobes (ATL), a key region identified as a supramodal semantic representational hub. Because of the methodological challenges to capture the exact function of this area, ATL-optimised fMRI was used to map the contribution of different ATL structures to a variety of experimental tasks used to probe both a social ability of theory of mind (ToM) and semantic cognition. The findings suggest that common to all of the tasks was the activation of a key ventrolateral ATL region that is often invisible to standard fMRI. The primary aim of Chapter 4 was to establish the degree of topological overlap between the cortical networks involved in social ToM and semantic tasks. Moreover, a set of secondary analyses accounted for possible methodological confounds, such as the stimulus format (verbal vs non-verbal) and input modality (visual vs auditory). The results highlight an extensive overlap between the two networks in regions strongly implicated in semantic cognition, including the bilateral ATLs and the left temporoparietal junction. The data in Chapter 5 is an outcome of a pilot study which investigated the involvement of the left and right ATLs in another domain of social cognition; facial emotion recognition (FER). After using repetitive TMS, significant differences were observed in reaction times on the facial valence categorization task after left ATL TMS. Finally, Chapter 6 outlines a discussion on the contribution of the empirical work in this thesis to novel insights into the neurobiological underpinnings of social cognition. These findings are supportive of the social semantic framework, which posits that social cognition draws upon cognitive processes related to semantic retrieval.

Date of Award	2023
Original language	English
Awarding Institution	Prifysgol Bangor | Bangor University
Supervisor	Richard Binney (Supervisor) & Paul E. Downing (Supervisor)