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It's about the right touch

The right touch is a matter of perception. Our brain is aided by a chain of senses that aim to interpret the world around us. However, our senses do not perceive external reality as it is; nonetheless, they alter it intentionally; Our senses are designed to enjoy stimuli that will contribute to our survival and dislike other stimulants that will impair our chances of survival. For example, food does not contain sweetness as a component; rather, it is the creation of our brain in response to the presence of glucose to motivate us to consume glucose, which is the primary fuel source for our body and brain; If we are not rewarded for our efforts, we won't consume enough energy for our physical activity, and we'll end up exhausted, unenergetic, and potentially fatal.

It is no secret that touch is one of the most important senses in our everyday lives.

While certain types of touch make us feel uneasy and hesitant, there is another sort of touch that we enjoy. Is the pleasure we derive through touch an indication that we must engage in this form of touch in our interpersonal relationships because it would be beneficial to us? We will address this question in the upcoming blog.

The two pathways of touch

Touch is absorbed by sensors in our skin, which are then transmitted to the brain for interpretation. According to research, there are two distinct channels for transmitting information to the brain. [1]: The first communication path is the rapid pathway, which sends information at a pace of 20 to 80 meters per second using shielded nerve fibers (covered in an insulating substance called myelin and known as I-beta fibers). This information travels directly into the brain's sensory and movement interpretation centers, allowing the brain to assess our position in space and acquire information about qualities such as the shape and texture of any body that comes into contact with us. This path is essential for our survival since it allows us to avoid danger and navigate our surroundings.

The second communication path is a slower path for information transmission through unshielded nerve fibers (without myelin isolation; C-fibers) that can transmit data at rates of 0.5 to 2 meters per second. These fibers are located in skin tissues surrounding hair, such as the arms, and they transmit information straight to the brain's emotional interpretation centers. They are susceptible to gentle and slow skin friction, such as stroking. But what is the purpose of this delayed information path, and how does it serve us?

The importance of touch [2]

The sense of touch is the first to develop, and it is the foundation for the comprehension of our bodies and self-identification. It becomes significant when the fetus is still inside the mother's womb throughout the third trimester of pregnancy. Studies indicate that the fetus is more interested in investigating the uterine wall by touching it in reaction to the mother caressing her belly. The slow-release C-fibers are activated during this investigation, and they generate oxytocin, a hormone that supports the development of the fetus' social brain, and beta-endorphin. This hormone relaxes and comforts the fetus. For the same reason, this is also why, once a baby is born, the parent's gentle rocking motion soothes the newborn and reduces crying, body movements, and heart rate.

After delivery, touch continues to play an essential part in the newborn's development. According to studies, moms communicate with their children through touch in 65 percent of their interactions, resulting in reduced behavioral stress and distress, lower levels of stress hormones like cortisol, a lower heart rate, more regular sleep and waking cycles, and better mood. Touch has a long-term impact in addition to being situational. For example, in premature babies, physical activation of C-fibers through stroking has been associated with improved weight gain, shorter hospital stays, and better nervous system responsiveness. This fascinating bodily need was observed in infants as well, who self-touched. In a study of six-month-old infants, newborns of moms with postpartum depression were much more occupied with self-touch than infants of non-depressed mothers. According to the study, regular self-touch is an attempt to compensate for their mothers' lack of meaningful interaction and maintain the several benefits of touch within their bodies and well-being through physical activation.

Touch continues to be a significant function in human social development and that of other mammals across both lifespans. Monkey observations, for example, have revealed that they engage in mutual grooming, such as delousing of skin parasites, for far longer than is physiologically required. This action promotes the release of the same two hormones, oxytocin, and beta-endorphin, which help with social bonding, relaxation, and pleasure. Touch is essential for bonding within the nuclear family and is the strongest predictor of positive emotions in children's development. Beyond its situational influence, how does touch produce such far-reaching transformations?

The epigenetics of touch- The study of how genes operate in our bodies and how they change over time [3].

In general, "epigenetics" refers to the factors that regulate how genes function in our biological systems; it is sensitive to environmental changes and remains relatively stable throughout the first five years of life. Parents' caressing touch, which activates the slow CC fibers, has been found to trigger epigenetic changes in their children that will last for years. In a 2019 study, for example, researchers discovered that mothers' prolonged caressing touch on their newborns was linked to higher expression of a gene that produces a stress-relieving receptor (a gene with the biological name NR3C1). As a result, these newborns were better able to deal with stress, were more relaxed, and had a less reactive stress system.

Furthermore, a longitudinal study of infants aged 5 to 18 months revealed that maternal touching was linked to increased expression of the oxytocin receptor, the same hormone linked to social bonding and nurturing.

This gentle touch has been proven to be linked to defensive epigenetics and to be resilient to the negative processes that can occur in the lives of delicate babies. For example, infants hospitalized in an intensive care unit after birth have epigenetic changes in a critical component of the serotonin pathway, the same hormone involved in many antidepressants and anxiety medications such as Prozac. They are more likely to suffer from depression and anxiety problems later in life due to these alterations—children whose parents used to stroke them while in the intensive care unit are protected from this phenomenon. Similarly, newborns of postpartum depressed moms have decreased expression of the gene that produces a receptor that shuts down the stress system (the same gene with the molecular name NR3C1), making them more vulnerable to stress, less calm, and biologically prone to adult anxiety disorders. Mothers who knew how to touch and caress their infants despite their depression had been spared with this epigenetic alteration.

These epigenetic discoveries are still initial due to the field's innovativeness. Still, they resemble the English romantic poet John Keats' remark that "touch has a memory" and support our instinct that touching is good for us in our closest social ties.

1. McGlone, F., J. Wessberg, and H. Olausson, Discriminative and affective touch: sensing and feeling. Neuron, 2014. 82(4): p. 737־755.

2. Cascio, C.J., D. Moore, and F. McGlone, Social touch and human development. Developmental cognitive neuroscience, 2019. 35: p. 5־11.

3. Wigley, ILCM, et al., Epigenetic protection: maternal touch and DNA־methylation in early life. Current Opinion in Behavioral Sciences, 2022. 43: p. 111־117.


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