Social COnceptual Knowledge

In Zahn et al., (2007) http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1851074/pdf/zpq6430.pdf, we showed selective activation of the right superior anterior temporal lobe for meaning relatedness judgments on social concept pairs (e.g. honour-brave) compared to less socially relevant concept pairs describing other functions of animals (e.g. trainable-useful, weaker effects on the left hemisphere did not survive significance thresholds). Bilateral middle anterior temporal lobe activation was shared for social and animal function concepts. Frontal and posterior temporo-parietal regions usually found to be activated for socially and morally relevant stimuli emerged as well when comparing social concepts versus animal function concepts. However, only the superior anterior temporal lobe exhibited increased activation with increasing richness of conceptual detail (descriptiveness: e.g. stingy is more descriptive than bad) as well as meaning (i.e. semantic) relatedness of social concept pairs used as stimuli (e.g. friendly-polite). Superior anterior temporal lobe activation was not significantly different between positive and negative social concepts in this study that controlled for descriptiveness of concepts. This is important because positive social concepts are less descriptive overall (according to our pre-study, but also according to previous studies by John, Hampson & Goldberg who kindly provided us with the stimuli referred to as "personality-trait" concepts in the literature:  http://www.ncbi.nlm.nih.gov/pubmed/2027078). 

  Zahn et al., 2009  http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2724922/pdf/awn343.pdf  included patients with neurodegenerative diseases affecting different brain regions to different degrees. Of the subgroup with frontotemporal lobar degeneration (N=29), N=10 showed significantly lower resting glucose metabolism in the right superior anterior temporal lobe on an individual case basis compared with elderly controls. The remaining N=19 patients had no significant neuronal dysfunction in this area and both groups had equal levels of damage to ventromedial, lateral orbitofrontal and frontopolar cortices as well as left anterior temporal lobe and anterior insula. In fact, there were no significant differences in metabolism between both groups outside the right anterior temporal area except for small portions of the right inferior frontal cortex and anterior insula. The group with damage to the right superior anterior temporal lobe showed selective impairments on social relative to animal function concepts on a novel test using concepts from our fMRI study. This selective impairment on social concepts was not found in the group without damage to this area. In Zahn et al., 2017, we replicated the association of selective social conceptual impairments with right anterior temporal lesions in frontotemporal lobar degeneration using grey matter volume in an independent sample and showed its dissociation from frontopolar lesion-associated impairments on knowledge of the long-term consequences of social behaviour.

 There is consistent evidence for selective involvement of the right superior anterior temporal lobe region in social conceptual knowledge. This evidence was derived from independent healthy control samples using different tasks (Zahn et al., 2007 & 2009) probing social concepts while modelling descriptiveness as the predicted stimulus parameter of major importance to conceptual representations in both studies. Importantly, independent evidence from patients with lesions and rTMS to disrupt function of the right anterior superior temporal lobe corroborated its necessity and selectivity for knowledge of social concepts (Pobric et al., 2016).