Intrinsic connectivity of anterior temporal lobe relates to individual differences in semantic retrieval for landmarks.

Contemporary neuroscientific accounts suggest that ventral anterior temporal lobe (ATL) acts as a bilateral heteromodal semantic hub, which is particularly critical for the specific-level knowledge needed to recognise unique entities, such as familiar landmarks and faces. There may also be graded functional differences between left and right ATL, relating to effects of modality (linguistic versus non-linguistic) and category (e.g., knowledge of people and places). Individual differences in intrinsic connectivity from left and right ATL might be associated with variation in semantic categorisation performance across these categories and modalities. We recorded resting-state fMRI in 74 individuals and, in a separate session, examined semantic categorisation. People with greater connectivity between left and right ATL were more efficient at categorising landmarks (e.g., Eiffel Tower), especially when these were presented visually. In addition, participants who showed stronger connectivity from right than left ATL to medial occipital cortex showed more efficient semantic categorisation of landmarks regardless of modality of presentation. These results can be interpreted in terms of graded differences in the patterns of connectivity across left and right ATL, which give rise to a bilateral yet partially segregated semantic 'hub'. More specifically, right ATL connectivity supports the efficient semantic categorisation of landmarks.

Controlled semantic summation correlates with intrinsic connectivity between default mode and control networks.

The capacity to identify aspects of meaning that overlap across multiple concepts may relate to individual differences in the strength of intrinsic connectivity within and between distinct brain networks supporting semantic cognition. This study examined a semantic summation task, which tested the capacity to detect weak overlapping aspects of meaning, in 76 participants who were also scanned with resting-state fMRI. We examined associations between summation and the intrinsic connectivity of semantically-relevant default mode and control network regions. These networks are implicated in information integration and controlled retrieval respectively. We found higher intrinsic connectivity between default and control networks was associated with better performance in the summation task. The same pattern of coupling between semantic default mode and control networks was not associated with more efficient retrieval of individual weak as opposed to strong associations in an additional cohort of around 200 participants, suggesting this pattern is specific to the summation of multiple concepts, rather than semantic task difficulty. Finally, higher connectivity within the default mode network was associated with better performance when selecting a word that was strongly-related to a single probe item, supporting the role of this network in more automatic aspects of semantic retrieval.