Touched by Loneliness - How Loneliness Impacts the Response to Observed Human Touch: a tDCS Study

Loneliness and socioemotional memory

Do chronically high-lonely individuals exhibit specific memory biases when recalling past social episodes? We explored negative memory biases, focusing on the recall of unfavourable social experiences and social memory biases, emphasizing the recall of social experiences irrespective of emotional valence. We conducted a dictionary-based semantic analysis of autobiographical episodes obtained from 4095 participants via four datasets. Participants recalled a positive, negative or emotionally neutral episode from their recent past. High-lonely individuals predominantly exhibited a decline in recalling positive social episodes, providing partial support for negative memory biases. However, both high- and low-lonely individuals were similarly inclined to recall negative social episodes. These results suggest that the primary issue among high-lonely individuals is the limited recall of positive social experiences rather than the general negativity in memory biases or the hypersensitivity to general social memories.

Role of medial prefrontal cortex and primary somatosensory cortex in self and other-directed vicarious social touch: a TMS study

Conflicting evidence points to the contribution of several key nodes of the 'social brain' to the processing of both discriminatory and affective qualities of interpersonal touch. Whether the primary somatosensory cortex (S1) and the medial prefrontal cortex (mPFC), two brain areas vital for tactile mirroring and affective mentalizing, play a functional role in shared representations of C-tactile (CT) targeted affective touch is still a matter of debate. Here, we used offline continuous theta-burst transcranial magnetic stimulation (cTBS) to mPFC, S1 and vertex (control) prior to participants providing ratings of vicarious touch pleasantness for self and others delivered across several body sites at CT-targeted velocities. We found that S1-cTBS led to a significant increase in touch ratings to the self, with this effect being positively associated to levels of interoceptive awareness. Conversely, mPFC-cTBS reduced pleasantness ratings for touch to another person. These effects were not specific for CT-optimal (slow) stroking velocities, but rather they applied to all types of social touch. Overall, our findings challenge the causal role of the S1 and mPFC in vicarious affective touch and suggest that self- vs other-directed vicarious touch responses might crucially depend on the specific involvement of key social networks in gentle tactile interactions.

Social behavior: Closing the gap for close encounters

Social touch can launch a cascade of emotions with enormous impact on the development and maintenance of emotional, cognitive and social functioning. A recent study identifies a novel pathway that facilitates physical contact via its direct impact on brain circuits controlling social behavior.

Decreased self-reported receiving of social touch and social support predict loneliness in healthy adults

Loneliness has emerged as a public health concern. Previous research has reported its deleterious effects on physical and mental health; however, some specific psychophysiological mechanisms in healthy adults remain to be elucidated. The aim of the current study is to investigate whether self-reported social support and social touch (giving and receiving social touch), as well as resting heart rate variability (HRV), are significant negative predictors of loneliness in healthy adults. The study sample consists of 120 healthy students (50% female) with a mean age of 21.85 years old (DP= 2.21). The students were asked to complete a psychiatric screening questionnaire utilizing loneliness, social support, and social touch scales. HRV was derived from an electrocardiographic signal recorded for 15 min, with the participant relaxed in a supine position. Linear regression analyses were conducted to evaluate loneliness as a function of social support, social touch (giving or receiving touch), and resting HRV. The results show that social support (p< 0.001) and social touch, specifically receiving touch (p< 0.002), accounted for a significant proportion of the variance in loneliness. However, neither giving touch nor resting HRV was a significant predictor of loneliness. The current study highlights specific psychosocial factors in healthy adults that should be considered as promising pathways in order to reduce or work toward preventing loneliness, thus promoting better health and well-being.