The multidimensional representational space of observed socio-affective touch experiences

Abstract

Observed touch interactions provide useful information on how others communicate with the external world. Previous studies revealed shared neural circuits between the direct experience and the passive observation of simple touch, such as being stroked/slapped. Here, we investigate the complexity of the neural representations underlying the understanding of others' socio-affective touch interactions. Importantly, we use a recently developed touch database that contains a larger range of more complex social and non-social touch interactions. Participants judged affective aspects of each touch event and were scanned while watching the same videos. Using correlational multivariate pattern analysis methods, we obtained neural similarity matrices in 18 regions of interest from five different networks: somatosensory, pain, the theory of mind, visual and motor regions. Among them, four networks except motor cortex represent the social nature of the touch, whereas fine-detailed affective information is reflected in more targeted areas such as social brain regions and somatosensory cortex. Lastly, individual social touch preference at the behavioral level was correlated with the involvement of somatosensory areas on representing affective information, suggesting that individuals with higher social touch preference exhibit stronger vicarious emotional responses to others' social touch experiences. Together, these results highlight the overall complexity and the individual modulation of the distributed neural representations underlying the processing of observed socio-affective touch.

Social touch observation in adults with autism: intact neural representations of affective meaning but lack of embodied resonance

“…In line with earlier research by others [54] and ourselves [19], we expect that on top of this univariate selectivity there will also be high multi-voxel selectivity for the distinction between social and nonsocial touch videos. The multiple regression analysis confirmed that almost every implicated ROI represents the distinction between social vs. non-social touch scenes, even after controlling for the effects of all the other regressor variables (e.g., low-level visual features and motor response).…”

“…In our previous study in NT adults, we demonstrated that individual differences in the strength of neural representations of socio-affective touch in the somatosensory cortex were associated with individual differences in the attitude towards social touch in daily life [19]. Here we further extend these findings and connect the neuroscientific findings with core pervasive autistic traits.…”

“…Lastly, building upon our previous study in NT adults [19], the current study provides evidence that individuals with stronger social touch avoidance or with more autistic traits experience diminished embodied somatosensory resonance with others. These findings extend recent studies that demonstrated an association between the level of activation in the somatosensory system during the observation of touch and inter-individual differences in empathy [23]- [26].…”

“…rubber band snapping) touch stimulations on the ventral surface of the right and left forearms while lying in the scanner. More information can be found in our previous study [19].…”

“…While this second line of research initially focused on the observation of fairly simple motor activities, implicating the premotor cortex and inferior parietal areas [15], [16], more recent studies have started investigating the observation of simple touch [5], [17], [18] and more complex interpersonal touch [19]. Concerning touch observation, accumulating evidence suggests that activated brain regions go beyond the visual cortex and include somatosensory regions involved in the processing of self-experienced touch [17], [20]- [22].…”