Skin touch sensations play a significant role in cognitive development. Because skin nerve density is much greater prior to adolescence, it is important to limit adverse sensory experiences during infancy and early childhood. Positive touch, such as massage, fosters parental bonding as well as healthy skin.
Skin touch sensations play a significant role in cognitive development. Because skin nerve density is much greater prior to adolescence, it is important to limit adverse sensory experiences during infancy and early childhood. Positive touch, such as massage, fosters parental bonding as well as healthy skin.
The skin is the largest sensory organ of the body. It plays an integral role in the neurological development of infants. The skin is linked to the brain via the peripheral nervous system, sharing the same embryological origin. Touch is the first sense to develop during early fetal life. This neurological connection is why skin-to-skin bonding is recommended at birth.
EV.E.I.L.S Program: Research On The Neurology Of Skin
In their EV.E.I.L.S program, Mustela has conducted 15 years of research to evaluate the skincare needs of infants and children. This was done in collaboration with a variety of experts in the field of dermatology, and involved both in vitro and clinical studies. The result was an intensive analysis of infant skin physiology, with an examination of epidermal functions, from its cutaneous barrier down to its lowest-lying layers. This enabled the development of a new, patented ingredient, Avocado Perseose. The Mustela product lines for infants and children are now reformulated to include this innovative ingredient.
Skin consists of three layers: epidermis, dermis, and hypodermis. The outermost epidermis protects the inner layers from anything outside of the body. The central dermis consists of blood vessels, sebaceous glands, nerves, and sweat glands, while the deeper hypodermis is primarily an insulation layer of fatty tissue.
Newborn skin is structurally different from adult skin. The stratum corneum is more irregular, and the junction between the epidermis and dermis is flatter. The dermis is thin and contains less collagen. These characteristics all result in skin that is more fragile and with less elasticity.
In the EV.E.I.L.S program, transepidermal water loss (TEWL) and natural moisturizing factor (NMF) were assessed. Newborns may have an increased TEWL, making it difficult for skin to remain hydrated. Skin is well hydrated at birth, but loses the ability to maintain it over the first six months of life. The NMF rebounds thereafter. In addition, newborn skin has a higher, more alkaline pH during the first week of life. This contributes to skin fragility, and increases the likelihood of infections or rashes. The protective barrier functions are immature at this stage, and skin is more vulnerable to irritants. Also, epidermal stem cells, present during fetal life, decrease after birth. These stem cells, involved in skin barrier construction and maturation, are more susceptible to damage than those of older children.
The epidermis and superficial dermis have specialized receptors that detect and differentiate various tactile stimuli. These mechanoreceptors are important for touch sensation.
Touch sensations differ on the glabrous skin of the palms and soles, and the non-glabrous skin on the remainder of the body. The hair follicles of non-glabrous skin have specific receptors that surround the hair follicles that enable emotional touch sensations.
Any stimulus detected by the skin triggers an electrical signal that travels from a receptor, through the dorsal horn of the spinal cord, and to the brain.
This connection between the skin and the brain results in cognitive responses to various touch sensations. Pain, for example, can provoke an aggressive emotional response. Stimulation of hairy skin nerves may produce an emotional or social response.
While the development of the skin’s barrier function is well documented, little is known about its interactions with the nervous system. In particular, the method of sensory nerve fiber formation during the first year of life is unknown.
In 2015, a study evaluated epidermal nerve ending density in 20 children aged seven and 17. Skin samples obtained by punch biopsy and suction blister revealed a nerve density threefold higher than that seen in adults. The skin density was higher in the skin samples of the seven year olds than in those of the teenage group. The focus of the EV.E.I.L.S neurosensory program has been to explore the evolution of nerve fibers within the skin of infants and children. It also investigated the influence of keratinocytes on the development of sensory neurons.
For comparison, adult skin recovered from surgical services was examined. From these samples, it was discovered that free nerve fibers and Meissner’s corpuscles are closely integrated.
In the surgical skin explant samples of children, however, the Meissner’s corpuscles were less organized, and, in some cases, barely visible.
Skin nerve density was then examined in surgical skin samples of various ages of children. The most dense nerve clusters were noted on the skin of six and 24 month olds. This density remained higher than that seen in adult skin until age seven. This poses the question of whether or not increased nerve density correlates to increased skin sensitivity in younger children.
To evaluate the role of keratinocytes on skin innervation, sensory neurons were cultured from keratinocytes of children and adults. The younger keratinocytes attracted more nerve fibers. The dendrites were longer and more numerous.
This shows that the young keratinocytes stimulate more neuronal growth than those of adults.
To discover why this phenomenon occurs, a genetic transcriptomic analysis was used to study which mediators secreted by keratinocytes attract nerves. It revealed that the keratinocytes of infants and children produce more nerve maturation and growth factors than those of adult skin
In order to replicate this analysis for further study, innervated
Stelaskin epidermal models were developed, each representing a different infant or child age.
First, neurons from undifferentiated stem cells were obtained. The red stained filaments indicated the presence of neurons. The TPRV1 receptors for pain and temperature regulation showed a green fluorescence. Nerve activity was verified by stimulation with lactic acid.
Step two involved culturing adult Stelaskin samples, and evaluating for neuronal penetration of the epidermis. The neurons migrated on days three and six, indicated by the green fluorescence.
Nerve viability and function was then studied. Results showed that an innervated epidermis has more cell activity than one that is not. This also proved that skin innervation promotes the proliferation of epidermal cells, and decreases apoptosis.
Step 4 further assessed infant innervated Stelaskin samples to study how nerve fibers travel. Since dermal nerve fibers were able to penetrate the epidermis, this shows that an in vitro skin model adequately replicates what is seen clinically in children.
The final step was to study differences in skin gene expression. A greater number of epidermal barrier genes were expressed on the innervated Stelaskin of children than that of adults. This increased level of expression may reflect that, due to its immaturity, ,younger skin requires further development depending on innervation.
At the conclusion of the EV.E.I.L.S neurosensory study, it was discovered that infant skin innervation, while present, is immature. The high density of the epidermal neurons promotes keratinocyte development. This is the first study to use an in vitro infant skin model to show that neurons play a major role in the formation of the skin barrier.
Touch is the first sense to develop in utero, followed by smell, taste, hearing, and vision. The fetus can sense pressure and temperature variations. Premature infants are able to detect simple forms of touch, but cannot differentiate one stimulus from another. Because this sense is immature, pain is often experienced very acutely.
The brain’s responses to touch differ during fetal life in comparison to after birth. Because of the hypersensitivity of the immature nervous system, premature birth predisposes children to tactile, auditory, and vestibular difficulties through the early childhood year. In full-term infants, the response time to tactile stimulation is slightly delayed when compared to that of adults.
There are certain stimuli that promote infant and child well-being and development. Prior to birth, the fetus memorizes all sensory stimuli. This influences subsequent emotional responses, and helps shape the nervous system. Massage is an effective pain reduction measure for premature infants, and may promote future learning and cognition. It also stimulates social development, and accelerates vision and brain maturation. In full-term infants, massage promotes emotional and physical development while fostering parental bonding.
Development and maturation of the nervous system requires sensory stimulation. Both touch and movement are important for this to occur. When these stimuli are limited, infant psychomotor and cognitive development may be impaired. In addition to tactile stimulation, paradoxical sleep promotes sensory nervous system development. This type of sleep begins at 30 weeks gestation, and decreases at 40 weeks.
Full-term newborns have a reduced cutaneous sensitivity threshold, and, therefore, perceive pain more intensely than adults. This perception is more marked in premature infants. Animal studies have shown that early pain exposure alters brain maturation, and leads to hyperalgesia during adulthood.
Tactile sensation develops very early in utero. Between seven to eight weeks gestation, perioral sensations are present. Sensation develops on facial and glabrous skin sensation by 11 weeks, and on the remaining body areas by 20 weeks.
Infant massage is beneficial for both premature and full-term neonates. It is associated with a reduced length of hospitalization, lower bilirubin levels, and improved infant-mother bonding.
Expanscience laboratories spent many years developing a massage oil specifically for infants. In a four week clinical study of infants and toddlers, massage with the proprietary oil improved skin hydration, texture, and elasticity. Parents felt that giving massages improved bonding and contributed to overall well-being.
These results prompted an additional study using a new “gel in oil” product. 75 infants and toddlers participated. Parents used the product for massage for 21 days. Data was collected seven and 21 days, and included a parent video recording.
This massage balm contains a blend of organic oils, along with stabilizers, and water.
COMPOSITION
9 ingredients: Organic Persea Gratissima and Sunflower Oils, Caprylic/Capric Triglycerides, Coco/Caprylate/Caprate, Glycerin, Sucrose Laurate and Stearate, Natural Fragrance, Water
After 21 days, parents felt that their infant’s or toddler’s skin condition improved, and the product was very well tolerated.
There was noticeable skin improvement, even after the first application.
After the first massage, infants seemed calmer and very receptive to it. Mothers reported feeling less tired and stressed, and enjoyed the bonding time with their baby
The parent videos were analyzed via artificial intelligence. On average, parents spent five minutes engaging in infant massage, and a joyful expression was documented 35 percent of the time.
The Role of Affective Touch
Affective touch is defined as a softer, superficial touch. It stimulates the insular cortex, or “social area,” of the brain. This kind of light touch fosters interpersonal communication between the infant and parent.
The nerve fibers responsible for affective touch are unmyelinated, and, therefore, transmit impulses slower than the nerves that respond to massage. These nerves primarily respond to deep pain, temperature, and pleasant touch.
Most health authorities recommend skin to skin contact with a parent immediately after birth, and throughout the first few days of life. This simple act promotes temperature regulation, and stabilizes the cardio-respiratory system. It also improves sleep duration, breastfeeding, and positive interactions with parents.
Much later than the onset of tactile sensation, the sense of smell develops around 30 weeks gestation. This sense is extremely important because it stimulates an interest in feeding, and encourages sucking. By the fourth day of life, most infants are aware of their mother’s scent. This scent later becomes associated with pleasure which stimulates oxygenation of the brain. It is also the first step toward olfactory memory.
Infants learn to associate their mother’s smell with comfort and decreased pain. As infants are exposed to other odors and fragrances, some may be detected as pleasant or offensive.
To further study this olfactory sense, Expanscience studied parent responses to the fragrance used in Mustela products. 45 mothers were exposed to a Mustela perfume for five minutes, and their reactions were documented via audio-video recordings and questionnaires. Heart rate elevations were also measured.
The results showed lower maternal heart rates, and overall pleasant reactions to this fragrance. The reactions were characterized as happy, loving, content, calm and peppy.
In the second phase of the study, parents were divided into two groups. Both were exposed to stressful stimuli, but only one group was provided a room infused with the Mustela perfume. The parents in the scent-exposed group exhibited much lower heart rates and vocal stress, demonstrating that the fragrance had a calming effect.
Based on these findings, the researchers have concluded that the Mustela fragrance exerts a calming effect on parents, and promotes positive interactions with infants and children.
In conclusion, it is clear that skin physiology and neurosensoriality are linked. Expanscience has presented a vision that integrates the tactile and olfactory senses in their approach to infant skincare. Their research has enabled the development of products that promote healthy skin as well as foster cognitive and emotional development.
