The neurostructural bases of empathy: morphometric evidence for a multicomponential approach

Abstract

The neural bases of individual differences in empathy subcomponents are still debated. We employed brain morphometry to investigate the neurostructural bases of individual and sex differences in specific empathy facets in 124 healthy individuals who completed the Balanced-Emotional-Empathy-Scale (BEES), and both the emotional/cognitive and self/other-oriented empathy subscales of the Interpersonal-Reactivity-Index (IRI). Univariate and multivariate morphometric analyses highlighted, respectively, voxels/clusters and whole structural networks where grey-matter volume reflected specific empathy subscores. Such morphometric properties were significantly related to individual differences in emotional empathy, while no evidence was found for structural networks underlying cognitive empathy. Personal distress correlated with grey-matter volume in the right insula and amygdala, likely mediating an affective sharing self-perceived as disturbing. Instead, empathic concern was associated with the medial precuneus and sensorimotor/inferior parietal cortex, possibly enabling empathic comprehension and prosocial behaviour mediated by attentional shift towards others. Female participants displayed larger grey-matter volume than male ones, related to higher emotional empathy, in limbic structures including amygdala and insula. These results ground multicomponential empathy models in specific neurostructural networks, representing a reference for future studies of empathic processing in health and disease.

Keywords: amygdala; brain morphometry; empathic concern; empathy; insula; intervention; personal distress; sex differences.

Figure 1

(A) Emotional and cognitive empathy (IRI subscores) in female (red) and male (blue) participants. The asterisks depict the statistical significance of post-hoc comparisons (***p<0.0001, **p<0.001, *p<0.05). (B) Statistical model assessing the correlation between BEES score and single IRI subscores, confirming the distinctiveness of Perspective-taking (p<0.001). To better convey the relationship between BEES and IRI (sub)scores and their modulation by sex, both panels depict their standardized values (the original values are reported in Supplementary Table S1 ).

Figure 2

The clusters (VBM analysis) and structural networks (SBM analysis) showing larger grey matter volume in females than males [(A, B), respectively] as well as in males than females [(C, D), respectively] (p<0.05 corrected for multiple comparisons). For SBM, different colors depict different independent components (i.e., “natural structural networks”; see 3.4).

Figure 3

The clusters (VBM analyses) and structural networks (SBM analyses) where GMV was positively related with BEES [(A, B), respectively], IRI Personal distress [(D, E) respectively] and IRI Empathic concern [(F, G) respectively] scores (p<0.05 corrected for multiple comparisons). In SBM results, BEES score reflects GMV in components 17 (violet), 18 (red-yellow), 19 (green) and 21 (blue), while Personal distress (PD) is associated with components 5 (light blue) and 31 (orange), and Empathic concern (EC) with components 19 (red) and 32 (green). The overlap between VBM and SBM neurostructural correlates of emotional empathy (BEES) in the bilateral amygdala and temporal pole is also shown (C), along with a scatterplot depicting the significant correlation (r=0.40, p<0.0001) between GMV in the left amygdala and BEES score (standardized values).

Figure 4

The dorsal medial parietal cluster where, in VBM analyses, GMV was positively related with IRI Fantasy (r=0.37, p<0.0001; A), alongside its overlap with the cluster - encompassing middle cingulate cortex and medial precuneus - where such correlation involved Empathic concern (violet color; B) (p<0.05 corrected for multiple comparisons).