Neuroanatomical Correlates of Social Intelligence Measured by the Guilford Test

Abstract

Social interactions are a crucial aspect of human behaviour. Numerous neurophysiological studies have focused on socio-cognitive processes associated with the so-called theory of mind—the ability to attribute mental states to oneself and others. Theory of mind is closely related to social intelligence defined as a set of abilities that facilitate effective social interactions. Social intelligence encompasses multiple theory of mind components and can be measured by the Four Factor Test of Social Intelligence (the Guilford-Sullivan test). However, it is unclear whether the differences in social intelligence are reflected in structural brain differences. During the experiment, 48 healthy right-handed individuals completed the Guilford-Sullivan test. T1-weighted structural MRI images were obtained for all participants. Voxel-based morphometry analysis was performed to reveal grey matter volume differences between the two groups (24 subjects in each)—with high social intelligence scores and with low social intelligence scores, respectively. Participants with high social intelligence scores had larger grey matter volumes of the bilateral caudate. The obtained results suggest the caudate nucleus involvement in the neural system of socio-cognitive processes, reflected by its structural characteristics.

The Interaction Between Caudate Nucleus and Regions Within the Theory of Mind Network as a Neural Basis for Social Intelligence

“…Thus, it is not surprising that SI can be characterized by the involvement of several neural systems, such as the ToM and reward systems. Such involvement potentially explains the discrepancies in our recent VBM results (Myznikov et al, 2021), where we expected to find an association between the level of SI and the GMV of ToM-related regions but did not. The present results show that although the caudate is not part of the ToM network, its interaction with ToM-associated regions differs between individuals with high SI and those with low SI.…”

“…The Russian adaptation of the four-factor test of SI, developed by J. Guilford and M. Sullivan (Guilford-Sullivan test), was used to measure the level of SI ( Mikhaylova, 2001 ). This test consists of four subtests: (1) Cartoon Predictions, (2) Expression Grouping, (3) Social Translations, and (4) Missing Cartoons (for a full description, see Myznikov et al, 2021 ). In the first subtest, the Cartoon Predictions, one was instructed to select one out of three cartoons, which appropriately continues the suggested situation.…”

“…However, there is limited evidence in the literature of an impact of the SI level on the interaction between the ToM system and the caudate. Although recent voxel-based morphometry (VBM) analysis ( Myznikov et al, 2021 ) did not reveal any correlations between the SI level and the GMV of ToM-related brain regions, it was hypothesized that the ToM network is involved in SI and can be identified via its functional interaction with the caudate nucleus as a vital region of the brain’s reward system. We performed a seed-based connectivity analysis of resting-state fMRI data and estimated correlations between SI level and functional connectivity (FC) to check this possibility.…”

“…Recently, it was demonstrated that the gray matter volume (GMV) within the caudate nucleus was positively associated with higher SI scores as measured by the Guilford-Sullivan test ( Myznikov et al, 2021 ). Although the caudate nucleus is known as a part of the “social brain,” there are insufficient data to demonstrate its relation to the ToM network.…”

“…We performed a seed-based connectivity analysis of resting-state fMRI data and estimated correlations between SI level and functional connectivity (FC) to check this possibility. Furthermore, due to the fact that previously we observed an association between gray matter volumes in the bilateral caudate and SI scores ( Myznikov et al, 2021 ) and that different subdivisions of the caudate nucleus are associated with distinct cognitive functions ( Robinson et al, 2012 ; Kuljiš et al, 2017 ), we used seeds for functional connectivity analysis located at the head and body of caudate nucleus (CN). The functional connectivity analysis found a dorsal/ventral distinction in caudate connectivity, specifically the most dorsal caudate seed was primarily associated with DLPFC and other cognitive control regions, and the most inferior caudate seed was primarily related to limbic areas ( Di Martino et al, 2008 ), and the similar findings were demonstrated by using diffusion tensor imaging techniques ( Kotz et al, 2013 ).…”