Lost Touch? Implications of Physical Touch for Physical Health.

OBJECTIVES: Growing research on the impact of physical touch on health has revealed links to lower blood pressure, higher oxytocin levels, and better sleep, but links to inflammation have not been fully explored. Physical touch may also buffer stress, underscoring its importance during the stressful time of living in the COVID-19 global pandemic-a time that has substantially limited social interactions and during which physical touch has been specifically advised against. METHOD: We analyze nationally representative longitudinal data on older adults (N = 1,124) from the National Social Life, Health, and Aging Project using cross-lagged path models. RESULTS: More frequent physical touch is significantly related to a lower likelihood of subsequent elevated inflammation. DISCUSSION: These findings highlight the importance of finding safe ways to incorporate physical touch, even in the aftermath of the COVID-19 pandemic.

Cognitive and emotional regulation processes of spontaneous facial self-touch are activated in the first milliseconds of touch: Replication of previous EEG findings and further insights.

Spontaneously touching one's own face (sFST) is an everyday behavior that occurs in people of all ages, worldwide. It is-as opposed to actively touching the own face-performed without directing one's attention to the action, and it serves neither instrumental (scratching, nose picking) nor communicative purposes. These sFST have been discussed in the context of self-regulation, emotional homeostasis, working memory processes, and attention focus. Even though self-touch research dates back decades, neuroimaging studies of this spontaneous behavior are basically nonexistent. To date, there is only one electroencephalography study that analyzed spectral power changes before and after sFST in 14 participants. The present study replicates the previous study on a larger sample. Sixty participants completed a delayed memory task of complex haptic relief stimuli while distracting sounds were played. During the retention interval 44 of the participants exhibited spontaneous face touch. Spectral power analyses corroborated the results of the replicated study. Decreased power shortly before sFST and increased power right after sFST indicated an involvement of regulation of attentional, emotional, and working memory processes. Additional analyses of spectral power changes during the skin contact phase of sFST revealed that significant neurophysiological changes do not occur while skin contact is in progress but at the beginning of sFST (movement toward face and initial skin contact). The present findings clearly illustrate the complexity of sFST and that the specific trigger mechanisms and functions of this spontaneous behavior need to be further investigated in controlled, experimental studies.

Hot to touch: the story of the 2021 Nobel Prize in Physiology or Medicine.

The 2021 Nobel Prize in Physiology or Medicine was awarded to Ardem Patapoutian and David Julius for their research on receptor channels responsible for the perception of touch and temperature. Somatosensation, an overarching sense that enables us to safely interface with the physical forces around and within us, is the fourth sensory modality to be recognized by the Nobel Committee. The story of the discovery of TRP and PIEZO channels, and subsequent investigations into their myriad roles in the perception of noxious and mild temperature, touch, pain, pressure and body position, is an archetype for how translational research into human and animal health is built on a foundation of excellence in basic science.

Social Touch Somatotopically Affects Mental Body Representations.

In pre-Covid days, many daily actions such as hand shaking or cheek kissing implied physical contact between our body and that of other people. With respect to touching an inanimate object (objectual touch), touching a person (social touch) concerns not only touching a human body, but also that this body belongs to a living person. This fundamental difference also may affect the way we figure our own movements and perceptions or, in other words, how we mentally represent our own body. To test this hypothesis, we asked 30 neurotypical participants to perform mental rotation of images representing hands, full bodies, and feet (an active cognitive task able to activate body representations without need of moving) in two tactile conditions: holding (one in each hand) either the thumbs of another person (social touch) or two plastic cylinders (objectual touch) of about the same circumference and size. Results showed that only mental rotation of hand images was affected by varying the tactile conditions, in that participants were faster during social than objectual touch. This suggests that the nature of hand-related tactile input (social or objectual touch) influences local (hand) and not global (body) mental representations of the body, and in a very somatotopic manner (hands but not feet). We interpret these findings with reference to the differentiation between sensorimotor (body schema) and visuospatial (body image) dynamics in the mental representation of our body. The present study shows that external social factors can affect the internal mental representations of one's own body.

Bridging skin, brain, and behavior to understand pleasurable social touch.

Social touch-the affiliative skin-to-skin contact between individuals-can rapidly evoke emotions of comfort, pleasure, or calm, and is essential for mental and physical well-being. Physical isolation from social support can be devastating. During the COVID-19 pandemic, we observed a global increase in suicidal ideation, anxiety, domestic violence, and worsening of pre-existing physical conditions, alerting society to our need to understand the neurobiology of social touch and how it promotes normal health. Gaining a mechanistic understanding of how sensory neuron stimulation induces pleasure, calm, and analgesia may reveal untapped therapeutic targets in the periphery for treatment of anxiety and depression, as well as social disorders and traumas in which social touch becomes aversive. Bridging the gap between stimulation in the skin and positive affect in the brain-especially during naturally occurring social touch behaviors-remains a challenge to the field. However, with advances in mouse genetics, behavioral quantification, and brain imaging approaches to measure neuronal firing and neurochemical release, completing this mechanistic picture may be on the horizon. Here, we summarize some exciting new findings about social touch in mammals, emphasizing both the peripheral and central nervous systems, with attempts to bridge the gap between external stimulation and internal representations in the brain.