Ever notice how even brief physical contact with a loved one or close friend, can leave you feeling calmer, happier, less stressed? It’s not just your imagination.”Most people think of touch as using their hands and fingers to touch things in our environment,” says François Kress, Chief Executive Officer, Feelmore Labs. “But the skin is also very powerful at recognizing a touch given to us by others.” 1,2 Using our sense of touch to explore our environment or manipulate an object is called discriminative touch.3 It’s a way of assessing physical data: Is the bath warm enough? Is this shirt too scratchy? But as social animals, humans are also innately sensitive to touch that contains emotional content—what scientists call affective touch. 3,4
This type of touch not only influences our mood, it can affect our physical health. 1,2 And it’s so important that we have a dedicated network of nerve fibers that carries this signal of calm and closeness directly into our brains.
Our skin is complex construction crisscrossed with fibers, millions of hair follicles and glands, blood vessels…and the sensory nerves that transmit our sense of touch. 4 Individual nerve cells respond to specific types of stimuli, like temperature, vibration, or pressure, thanks to projections (known as nerve endings) embedded in specialized sensors in the tissue of the skin. When a nerve ending is activated by a particular stimulus, a signal is sent along the nerve fiber (the cells’ thread-like connection to other nerves) that ultimately reaches the brain. 3
Researchers have identified several kinds of sensory nerves in our skin—including one particular type, called CT-afferent, that seems uninvolved in discriminative touch. These cells are picky about the stimulus they respond to. They become most active when our skin is stroked, with low pressure, at a speed between one and ten centimeters per second. 5,6 That’s the same gentle, pleasant stroking we instinctively use to express affection to someone close to us, whether it’s a friend who needs consoling, a romantic partner we’re cuddling with, or an upset child we’re trying to soothe.
Our network of CT nerves seems especially tuned to the comforting feeling of social contact. And research bears this out. One study asked people to rate the pleasantness of a brush across their skin at various speeds, and it turned out that the most pleasant feelings were reported when those CT nerve cells were most active. 6 Another study found that people smiled more when CT nerves were stimulated, compared to skin contact where no CT nerves were present. 7 (Interestingly, CT afferents are absent in areas of the skin where hair doesn’t grow and discriminative touch is particularly important, like the palms of our hands, the palm sides of our fingers, and the soles of our feet.) 6. eg.
Nerves that are involved in discriminative touch—called Aβ afferents—ultimately transmit their information to an area of the brain called the somatosensory cortex. The physical sensations of touch are processed there, creating an internal, head-to toe map of our body. 3,8 These signals reach the brain much sooner than signats from CT afferent nerves. The relative slowness of CT signals is a clue that they’re not transmitting discriminative information: If you’re touching something sharp or hot, for example, you need to know it ASAP.
Another sign that CT nerves serve a different purpose is that they seem wired into a different region of the brain entirely. Imaging studies have shown that when CT nerves are stimulated, a part of the brain called the insular cortex becomes activated. 9 This area is sometimes called the “gateway between our senses and our emotions”4, because it integrates our sensory experiences with the emotional tone of those experiences. It’s a small but mighty lump of tissue that helps us make decisions, feel empathy, and react to social situations. 10 The direct connection between our skin and this part of the brain makes a convincing explanation for why the light touch of someone you love can carry so much emotional weight.
Though researchers are still mapping the complex connections, we do know that the brain responds to affective touch by triggering all sorts of physical and emotional reactions. For example: Touch stimulates the release of oxytocin, a brain chemical associated with parental and romantic attachment, and it lowers the levels of the stress hormone cortisol. 2
Affective touch can reduce pain and stress. 2, 11 It’s even been found that hospital patients touched by a nurse the day before their operation show lower stress levels and reduced heart rate and blood pressure. 2
Socially speaking, receiving a friendly touch makes you more likely to think positively about someone, to do a favor for a stranger, to buy something from a salesperson, or to tip a server. 2 One study found that people felt less ostracized after being excluded from a game if they were given a slow, CT-stimulating touch—but not if the touch was faster than that. 12
What will be the impact of losing opportunities for affective touch during the coronavirus quarantine? Time will tell, but the effects may be widespread, says J. Leon Morales- Quezada, M.D., Research Associate Director at the Neuromodulation Center of the Spaulding Rehabilitation Hospital, Harvard Medical School. “The combined effects of uncertainty due to the Covid-19, social isolation, and economic instability has the potential to trigger a cascade of mental health issues,” he explains. Interacting via Zoom or Facetime is valuable, but something significant is lost when touch is out of the equation. “Affective touch generates emotional regulations that can enhance the effects of social interaction,” Dr. Morales-Quezada notes.
And the truth is, we were already undervaluing the importance of touch even before the pandemic made social interactions so complicated. “We in the US were already avoiding touch for many decades. So we went from a low level of touch, and all the ramifications, to no touch,” says François Kress. Perhaps when conditions change, we’ll realize what we missed, and welcome affective touch into our lives with open arms.
 Gallace et al Neuroscience and Biobehavioral Reviews 34 (2010) 246–259 sciencedirect.com/science/article/abs/pii/S0149763408001723
 Field Developmental Review 30 (2010) 367–383 sciencedirect.com/science/article/abs/pii/S0273229711000025
 McGlone et al Neuroscience and Biobehavioral Reviews 34 (2010) 148–159 sciencedirect.com/science/article/abs/pii/S014976340900116X
 Mcglone et al Neuron 82 (4) 2014 pp 737-755 https://doi.org/10.1016/j.neuron.2014.05.001
 Taneja et al Psychological Research doi: 10.1007/s00426-019-01253-8
 Loken et al Nature Neuroscience May 2009 DOI: 10.1038/nn.2312
 Pawling et al PLOS One 2017 doi.org/10.1371/journal.pone.0173457
 Kropf Braz J Psychiatry 2019 May-Jun;41(3):261-269 doi:10.1590/1516-4446-2018- 0183
 Olausson et al Neurosci. Biobehav. Rev. (2008) doi:10.1016/j.neubiorev.2008.09.011
 Gogalla Current Biology 27, R573–R591, June 19, 2017 cell.com/current-biology/fulltext/S0960-9822(17)30546-8
 Krahe et al Phil.Trans. R. Soc. B 371: 20160009. dx.doi.org/10.1098/rstb.2016.0009
 von Mohr et al Scientific Reports volume 7, Article number: 13516 (2017) doi.org/10.1038/s41598-017-13355-7