1. Neurophysiology of touch

Man becomes aware of the external environment through information or signals transmitted via nerve fibers. These originate in the epidermis and dermis: either via specialized organs (receptors or sensitive corpuscles), or via a simple bulge at the end of the nerve fiber.

Tactile (or somatic) sensitivity is divided into two categories:

• active sensitivity (or proprioceptive sensitivity) linked to muscle and joint receptors;

• passive or cutaneous sensitivity (exteroceptive), including mechanical and thermal sensitivities.

With the exception of the anthropoid ape, no animal has a tactile sensitivity equivalent to that of the human hand, whose maximum acuity is reached at the digital level. Sensitivity depends closely on the density of tactile receptors...