White matter connectivity in brain networks supporting social and affective processing predicts real-world social network characteristics

Abstract

Human behavior is embedded in social networks. Certain characteristics of the positions that people occupy within these networks appear to be stable within individuals. Such traits likely stem in part from individual differences in how people tend to think and behave, which may be driven by individual differences in the neuroanatomy supporting socio-affective processing. To investigate this possibility, we reconstructed the full social networks of three graduate student cohorts (N = 275; N = 279; N = 285), a subset of whom (N = 112) underwent diffusion magnetic resonance imaging. Although no single tract in isolation appears to be necessary or sufficient to predict social network characteristics, distributed patterns of white matter microstructural integrity in brain networks supporting social and affective processing predict eigenvector centrality (how well-connected someone is to well-connected others) and brokerage (how much one connects otherwise unconnected others). Thus, where individuals sit in their real-world social networks is reflected in their structural brain networks. More broadly, these results suggest that the application of data-driven methods to neuroimaging data can be a promising approach to investigate how brains shape and are shaped by individuals’ positions in their real-world social networks.

Four errors and a fallacy: pitfalls for the unwary in comparative brain analyses

“…The link between these outcomes and the Social Brain Hypothesis is direct, with mentalising (the ability to understand others' perspectives and intentions) as the key intervening variable. Upwards of two dozen neuroimaging studies (some with very large samples indeed) for both humans (Bickart et al, 2011(Bickart et al, , 2012Lewis et al, 2011;Horv ath et al, 2011;Powell et al, 2012;Kanai et al, 2012;Von Der Heide, Vyas & Olson, 2014;Dziura & Thompson, 2014;Hampton et al, 2016;Pillemer, Holtzer & Blumen, 2017;Kwak et al, 2018;Noonan et al, 2018;Spagna et al, 2018;Kiesow et al, 2020;Peer et al, 2021;Hyon et al, 2022) and Old World monkeys (Sallet et al, 2011;Meguerditchian et al, 2020;Testard et al, 2022) provide evidence that individual differences in the volume of specific brain regions [notably those known to be associated with mentalising skills in both macaques (Roumazeilles et al 2021) and humans (Carrington & Bailey, 2009;van Overwalle, 2009;Andrews-Hanna et al, 2010)] correlate with individual-level differences in social network (or living-group) size (see also Bzdok & Dunbar, 2020. Powell et al (2012) used path analysis with individual-level neuroimaging data to show that the causal sequence is: prefrontal cortex volume determines mentalising skills which, in turn, determine social network size.…”

Evolutionary Lags in the Primate Brain Size/Body Size Relationship

“…Large body size and large group size have long been known to be alternative strategies that primates use to reduce predation risk in order to occupy habitats subject to high predator densities (Dunbar 1988; Shultz et al 2004; Shultz & Dunbar 2006; Shultz & Finlayson 2010). In primates at least, group size has been shown to correlate strongly with brain size, both within (humans: Bickart et al 2011; Powell et al, 2012; Kanai et al, 2012; Kwak et al, 2018; Noonan et al, 2018; Spagna et al, 2018; Peer et al, 2021; Hyon et al, 2022; monkeys: Sallet et al, 2011; Meguerditchian et al, 2020; Testard et al, 2022) and between species (Dunbar 1998; Pérez-Barbería et al 2007; Dunbar & Shultz 2007, 2010, 2017, 2021, 2023; Shultz & Dunbar 2007, 2010, 2022), because the cognitive demands imposed by increasing social group size in the kind of bonded societies characteristic of primates are neurally very demanding (Lewis et al 2017; Dunbar 2018; Kiesow et al 2020; Dunbar & Shultz 2021). (Note: the few cases claiming that brain size and group size are uncorrelated all turn out to be statistically flawed: they inadvertently tested hypotheses about constraints, not hypotheses about selection effects.…”

White matter connectivity and social functioning in survivors of pediatric brain tumor

“…Structural connectivity is vital to network function and various social information processes, including face processing [11,12] and empathy [13]. Notably, white matter integrity appears related to connectedness within real-world social networks [14].…”