Empathizing associates with mean diffusivity

Abstract

Empathizing is defined as "the drive to identify another's mental states and to respond to these with an appropriate emotion" and systemizing is defined as "the drive to the drive to analyze and construct rule-based systems". While mean diffusivity (MD) has been robustly associated with several cognitive traits and disorders related with empathizing and systemizing, its direct correlation with empathizing and systemizing remains to be investigated. We undertook voxel-by-voxel investigations of regional MD to discover microstructural correlates of empathizing, systemizing, and the discrepancy between them (D score: systemizing - empathizing). Whole-brain analyses of covariance revealed that across both sexes, empathizing was positively correlated with MD of (a) an anatomical cluster that primarily spreads in the areas in and adjacent to the left dorsolateral prefrontal cortex, left anterior to the middle cingulate cortex, and left insula and (b) an anatomical cluster of the left postcentral gyrus and left rolandic operculum. The former overlaps with positive MD correlates of cooperativeness. The D score and systemizing did not show significant correlations. In conclusion, while increased MD has generally been associated with reduced neural tissues and possibly area function, higher empathizing and cooperativeness were commonly reflected by greater MD values in areas (a) that mainly overlap with areas that play a key role in emotional salience and empathy. In addition, higher empathizing was correlated with greater MD values in areas (b) that play a key role in the mirror neuron system.

Figure 1

Histograms showing the EQ scores (a) and SQ scores (b) for all subjects.

Figure 2

Histograms showing the D scores for all subjects.

Figure 3

The main positive effects (regardless of sex) of the EQ score across both sexes. (a,c) The results shown were obtained using a threshold of threshold-free cluster enhancement (TFCE) of P < 0.05, based on 5000 permutations. The results were corrected at the whole-brain level. Regions with significant correlations are overlaid on a “single subject” T1 image of SPM8. The color represents the strength of the TFCE value. (a) Regions with negative main positive effects of EQ scores on MD across both sexes were observed in the areas in and adjacent to the left dorsolateral prefrontal cortex, left ACC, and left insula. (b) Scatter plot of the associations between EQ scores and mean MD values for this cluster of (a). (c) Regions with positive main positive effects of EQ scores on MD across both sexes were observed in the areas of the left postcentral gyrus and left rolandic operculum. (d) Scatter plot of the associations between EQ scores and mean MD values for this cluster of (b).

Figure 4

The main positive effects (regardless of sex) of cooperativeness score across both sexes. (a) The results shown were obtained using a threshold of threshold-free cluster enhancement (TFCE) of P < 0.05, based on 5000 permutations. The results were corrected at the whole brain level. Regions with significant correlations are overlaid on a “single subject” T1 image of SPM8. The color represents the strength of the TFCE value. Regions with negative main positive effects of cooperativeness scores on MD across both sexes were observed in the areas in and adjacent to the gray and white matter areas of bilateral frontal and parietal areas. (b–d) Scatter plot of the associations between EQ scores and mean MD values for the cluster spreading mainly across the posterior areas of the right hemisphere (b), mean MD values for the cluster spreading mainly across the left hemisphere (c), mean MD values for the cluster spreading mainly across the anterior areas of the right hemisphere (d).