لخّصلي

The skin and brain are anatomically and functionally connected in a bi-directional manner (the skin-brain axis and brain-skin axis) as they arise from a common embryonic origin, the ectoderm.Somatosensory inputs from the skin are transmitted to the postcentral gyrus, where the entire surface of the body is represented by the sensory homunculus.These inputs are associated with emotional, behavioural, neurovegetative, endocrine and immune reactions.Cutaneous inputs may even profoundly influence neural development.

The skin and brain are anatomically and functionally connected in a bi-directional manner (the skin-brain axis and brain-skin axis) as they arise from a common embryonic origin, the ectoderm.

Somatosensory inputs from the skin are transmitted to the postcentral gyrus, where the entire surface of the body is represented by the sensory homunculus. These inputs are associated with emotional, behavioural, neurovegetative, endocrine and immune reactions. Cutaneous inputs may even profoundly influence neural development. For example, regular gentle touch during childhood may be essential for the development of a “social brain” as C-tactile afferents exercise brain networks involved in social-emotional learning.1-4 Low-intensity stimulation of the skin may also influence short-term social interactions and well-being by activating oxytocinergic neurons in the paraventricular nuclei, which have projections to important regulatory brain areas such as the limbic system.5

The brain influences the skin via two physiological pathways, the autonomic nervous system and the hypothalamic-pituitary-adrenal axis (HPA axis). Under normal circumstances HPA axis hormones contribute to skin homoeostasis, anti-inflammatory balance and antimicrobial defense.6-8 However, under stress, the HPA axis may be altered resulting in proinflammatory hormonal effects, resistance of tissue receptors to glucocorticoids and mast cell activation in the skin