CCIL Psychology: Francis McGlone (Unilever Research, Liverpool)

Francis McGlone (Unilever Research, Liverpool)

Discriminative & Affective Touch: Sense and Sensibility 

Abstract:

The skin senses have traditionally been described as telling us about touch, temperature and pain, and there is a relatively robust understanding of the peripheral and central neural counterparts of this somatosensory system.  It has been known for some time that in mammals there is a class of peripheral nerve fibres c-fibres - that respond to light mechanical stimulation (stroking) of the body surface, but that in primates, and especially humans, this system has been viewed as vestigial at best.  In humans, c-fibres are classified as either subserving pain sensibility or autonomic skin functions, but there is increasing evidence that a functional 'pleasure' c-fibre system exists in human skin – notably only in hairy skin and not in on the palms of the hands or the soles of the feet.

Employing microneurography, a population of c-fbres that are preferentially activated by gentle stroking movements across their receptive fields have been identified.  Recent evidence, employing anatomical, electrophysiological, psychophysical, behavioural and brain-imaging techniques, showing how the body responds to light touch and where in the brain the 'pleasure' nerves project their messages. Finding where in the brain this form of touch projects, will be discussed .  It is becoming clear that the sense of touch serves much more than pure discrimination e.g. how hard, cold or smooth something is, but also conveys information about how pleasant or rewarding – as well as unpleasant – touch can be when being touched or touching the body surface   There is now converging evidence of this system's role in affective touch, and in particular its role in inter-personal affiliative touch – a social dimension to tactile communication.