Mechanotransduction in the human hair follicle: implications in somatosensation

The sense of touch with its cornerstone in somatosensation permits object recognition and texture discrimination via sensing of mechanical forces through the skin. The sensory neurons located in the peripheral nervous system and their specialized end-organs are tuned to transform and interpret the broad spectrum of mechanical stimulus that compose our tactile world. Mechanotransduction permits the transformation and integration of these mechanical applied signals, creating a conceptual tactile framework that, ultimately, permit organisms to interpret and communicate with the physical and social environment. Recent advances in genetic reporter mice has provided evidence that these sensory neurons innervate the skin in a differential manner depending on one crucial factor: the presence or absence of hair follicles. With the presence of these organelles, the neuronal axon terminals form lanceolate end-organs surrounding hair follicles with designated molecular, electrophysiological and functional features. Although important progress has been done in such murine models, less is known of the structure and function of this specialized lanceolate sensory end-organs in humans. The purpose of this thesis will focus in investigating the patterns of hair follicle innervation in human skin and propose plausible mechanisms of mechanical activation, for example, after hair deflection. The ultimate goal will be to confirm a potential phylogenetically continuum of the molecular and electrophysiological proprieties between mice and human hair follicle sensory end-organs.