Unveiling the dynamic interplay between the hub- and spoke-components of the brain's semantic system and its impact on human behaviour.

The neural architecture of semantic knowledge comprises two key structures: (i) A set of widely dispersed regions, located adjacent to the sensorimotor cortices, serve as spokes that represent various modality-specific and context-dependent contents. (ii) The anterior-temporal lobe (ATL) serves as a hub that computes the nonlinear mappings required to transform modality-specific information into pan-modality, multifaceted concepts. Little is understood regarding whether neural dynamics between the hub and spokes might flexibly alter depending on the nature of a concept and how it impinges upon behaviour. Using fMRI, we demonstrate for the first time that the ATL serves as a 'pivot' which dynamically forms flexible long-range networks with cortical modules specialised for different domains (in the present case, the knowledge about actions and places). In two experiments, we manipulated semantic congruity and asked participants to recognise visually presented items. In Experiment 1 (dual-object displays), the ATL increased its functional coupling with the bilateral frontoparietal action-sensitive system when the objects formed a pair that permitted semantically meaningful action. In Experiment 2 (objects embedded in a scene), the ATL augmented its coupling with the retrosplenial cortex of the place-sensitive system when the objects and scene formed a semantically coherent ensemble. Causative connectivity revealed that, while communication between the hub and spokes was bidirectional, the hub's directional impact on spokes dwarfed the strength of the inverse spoke-to-hub connectivity. Furthermore, the size of behavioural congruity effects co-varied with the strength of neural coupling between the ATL hub and action- / place-related spokes, evident both at the within-individual level (the behavioural fluctuation across scanning runs) and between-individual level (the behavioural variation of between participants). Together, these findings have important implications for understanding the machinery that links neural dynamics with semantic cognition

Bipartite Functional Fractionation within the Default Network Supports Disparate Forms of Internally Oriented Cognition.

Our understanding about the functionality of the brain's default network (DN) has significantly evolved over the past decade. Whereas traditional views define this network based on its suspension/disengagement during task-oriented behavior, contemporary accounts have characterized various situations wherein the DN actively contributes to task performance. However, it is unclear how different task-contexts drive componential regions of the DN to coalesce into a unitary network and fractionate into different subnetworks. Here we report a compendium of evidence that provides answers to these questions. Across multiple analyses, we found a striking dyadic structure within the DN in terms of the profiles of task-triggered fMRI response and effective connectivity, significantly extending beyond previous inferences based on meta-analysis and resting-state activities. In this dichotomy, one subset of DN regions prefers mental activities "interfacing with" perceptible events, while the other subset prefers activities "detached from" perceptible events. While both show a common "aversion" to sensory-motoric activities, their differential preferences manifest a subdivision that sheds light upon the taxonomy of the brain's memory systems. This dichotomy is consistent with proposals of a macroscale gradational structure spanning across the cerebrum. This gradient increases its representational complexity, from primitive sensory-motoric processing, through lexical-semantic representations, to elaborated self-generated thoughts.This research was funded by an MRC programme grant to MALR (MR/R023883/1) and a Sir Henry Wellcome Fellowship (201381/Z/16/Z) to RC

Neuroimaging investigations of cortical specialisation for different types of semantic knowledge

Embodied theories proposed that semantic knowledge is grounded in motor and perceptual experiences. This leads to two questions: (1) whether the neural underpinnings of perception are also necessary for semantic cognition; (2) how do biases towards different sensorimotor experiences cause brain regions to specialise for particular types of semantic information. This thesis tackles these questions in a series of neuroimaging and behavioural investigations. Regarding question 1, strong embodiment theory holds that semantic representation is reenactment of corresponding experiences, and brain regions for perception are necessary for comprehending modality-specific concepts. However, the weak embodiment view argues that reenactment may not be necessary, and areas near to perceiving regions may be sufficient to support semantic representation. In the particular case of motion concepts, lateral occipital temporal cortex (LOTC) has been long identified as an important area, but the roles of its different subregions are still uncertain. Chapter 3 examined how different parts of LOTC reacted to written descriptions of motion and static events, using multiple analysis methods. A series of anterior to posterior sub-regions were analyzed through univariate, multivariate pattern analysis (MVPA), and psychophysical interaction (PPI) analyses. MVPA revealed strongest decoding effects for motion vs. static events in the posterior parts of LOTC, including both visual motion area (V5) and posterior middle temporal gyrus (pMTG). In contrast, only the middle portion of LOTC showed increased activation for motion sentences in univariate analyses. PPI analyses showed increased functional connectivity between posterior LOTC and the multiple demand network for motion events. These findings suggest that posterior LOTC, which overlapped with the motion perception V5 region, is selectively involved in comprehending motion events, while the anterior part of LOTC contributes to general semantic processing. Regarding question 2, the hub-and-spoke theory suggests that anterior temporal lobe (ATL) acts as a hub, using inputs from modality-specific regions to construct multimodal concepts. However, some researchers propose temporal parietal cortex (TPC) as an additional hub, specialised in processing and integrating interaction and contextual information (e.g., for actions and locations). These hypotheses are summarized as the "dual-hub theory" and different aspects of this theory were investigated in in Chapters 4 and 5. Chapter 4 focuses on taxonomic and thematic relations. Taxonomic relations (or categorical relations) occur when two concepts belong to the same category (e.g., ‘dog’ and ‘wolf’ are both canines). In contrast, thematic relations (or associative relations) refer to situations that two concepts co-occur in events or scenes (e.g., ‘dog’ and ‘bone’), focusing on the interaction or association between concepts. Some studies have indicated ATL specialization for taxonomic relations and TPC specialization for thematic relations, but others have reported inconsistent or even converse results. Thus Chapter 4 first conducted an activation likelihood estimation (ALE) meta-analysis of neuroimaging studies contrasting taxonomic and thematic relations. This found that thematic relations reliably engage action and location processing regions (left pMTG and SMG), while taxonomic relations only showed consistent effects in the right occipital lobe. A primed semantic judgement task was then used to test the dual-hub theory’s prediction that taxonomic relations are heavily reliant on colour and shape knowledge, while thematic relations rely on action and location knowledge. This behavioural experiment revealed that action or location priming facilitated thematic relation processing, but colour and shape did not lead to priming effects for taxonomic relations. This indicates that thematic relations rely more on action and location knowledge, which may explain why the preferentially engage TPC, whereas taxonomic relations are not specifically linked to shape and colour features. This may explain why they did not preferentially engage left ATL. Chapter 5 concentrates on event and object concepts. Previous studies suggest ATL specialization for coding similarity of objects’ semantics, and angular gyrus (AG) specialization for sentence and event structure representation. In addition, in neuroimaging studies, event semantics are usually investigated using complex temporally extended stimuli, unlike than the single-concept stimuli used to investigate object semantics. Thus chapter 5 used representational similarity analysis (RSA), univariate analysis, and PPI analysis to explore neural activation patterns for event and object concepts presented as static images. Bilateral AGs encoded semantic similarity for event concepts, with the left AG also coding object similarity. Bilateral ATLs encoded semantic similarity for object concepts but also for events. Left ATL exhibited stronger coding for events than objects. PPI analysis revealed stronger connections between left ATL and right pMTG, and between right AG and bilateral inferior temporal gyrus (ITG) and middle occipital gyrus, for event concepts compared to object concepts. Consistent with the meta-analysis in chapter 4, the results in chapter 5 support the idea of partial specialization in AG for event semantics but do not support ATL specialization for object semantics. In fact, both the meta-analysis and chapter 5 findings suggest greater ATL involvement in coding objects' associations compared to their similarity. To conclude, the thesis provides support for the idea that perceptual brain regions are engaged in conceptual processing, in the case of motion concepts. It also provides evidence for a specialised role for TPC regions in processing thematic relations (pMTG) and event concepts (AG). There was mixed evidence for specialisation within the ATLs and this remains an important target for future research

Intersections between semantic cognition and affective processing: Insights from neuropsychology and neuroimaging

Semantic cognition, the basis for our understanding of the world, is supported by both the storage of semantic representations and the ability to flexibly retrieve them – semantic control. Semantic control dictates our ability to parse ambiguous information, and is supported by a distributed semantic control network (SCN). Patients with semantic aphasia (SA) experience multimodal semantic control deficits following left hemisphere stroke. Using cognitive neuropsychology and neuroimaging, this thesis further explores the neural bases of semantic retrieval and tests the relevance of semantic control to emotion, valence, and reward. Key findings were: (i) SA patients experience diffuse disconnection beyond lesion site. Lesion and structural disconnection of left-lateralised SCN nodes predict semantic impairment, while domain-general control impairment is predicted by lesion to adjacent fronto-parietal regions and by interhemispheric structural disconnection. (ii) SA patients present with impaired categorisation of facial emotion portrayals, susceptible to effects of cues and miscues. (iii) Valence congruency between words facilitates semantic matching, while semantic relatedness facilitates valence matching. SA patients present with impaired valence matching, exacerbated by semantic distractors. (iv) Impairments in the retrieval of weak associations can be facilitated in SA using cued extrinsic rewards. (v) The retrieval of both contextual and emotional associations is associated with activation in SCN, with these tasks being dissociated by default mode subnetworks. Effects of retrieval demands on the default mode network run orthogonally to effects of task. This thesis provides novel insight into the complex neural basis of retrieving meaning and emotion. It also contributes to our understanding of the impairments in SA, as well as how they can be ameliorated. Finally, this thesis supplements conceptually-focused models of emotion processing, stressing a role of semantic control. This work contributes to an increasingly clear understanding of controlled semantic retrieval and its contribution to cognition across domains

The professional learning of academics in higher education: a sociomaterial perspective

Introduction For academics in UK Higher Education (HE), professional learning (PL) is a complex endeavour involving a multitude of (in)formal learning encounters. However, these PL encounters are at risk as academics prioritised conflicting knowledge domains and negotiate various social and material engagements that can enable or encumber these encounters. This thesis reports on research that attempts to illuminate these sociomaterial entanglements using Actor-Network Theory and Non-Representational Theory as a theoretical framework. Methods A transformative mixed method case study of a single UK university using content analysis, questionnaire, interview and photovoice methods were undertaken. Twelve academic staff, with module leader responsibilities, were selected from the academic staff questionnaire (n:182) to be interviewed and photograph their PL experiences. Unique to sociomaterial investigation was the photovoice method, enabling the participants to become empowered as co-researchers. Results The analysis of the data suggests that academics tend to be strategic in prioritising conflicting knowledge domains. In the case of knowledge not related to their subject discipline, academics will often fast-track information from a "knowledgeable other". Furthermore, academics will construct "surrogate" or "transient" spaces in which to seek refuge from the various disruptions and interruptions generated by their institution. Academics will use these spaces for uninterrupted learning or work and as a means for promoting self-care. Discussion The study identified four interrelated spatial properties (transient, affective, controlled and immersive), which provides an explanation why some spaces were more conducive to PL than other spaces. Furthermore, space is composed of multiple and interconnected spatial configurations that coalesce into a single spatial configuration, which I call coalescent space. The study also proposes a number of future research directions involving the PL of early career academics and academics on sessional contract

Intelligence, Creativity and Fantasy

UID/HIS/04666/2019 This is the 2nd volume of PHI series, published by CRC Press, the 4th published by CRC Press and the 5th volume of PHI proceedings.The texts presented in Proportion Harmonies and Identities (PHI) - INTELLIGENCE, CREATIVITY AND FANTASY were compiled with the intent to establish a multidisciplinary platform for the presentation, interaction and dissemination of research. The aim is also to foster the awareness and discussion on the topics of Harmony and Proportion with a focus on different visions relevant to Architecture, Arts and Humanities, Design, Engineering, Social and Natural Sciences, and their importance and benefits for the sense of both individual and community identity. The idea of modernity has been a significant motor for development since the Western Early Modern Age. Its theoretical and practical foundations have become the working tools of scientists, philosophers, and artists, who seek strategies and policies to accelerate the development process in different contexts.authorsversionpublishe