Primary somatosensory cortex discriminates affective significance in social touch

Abstract

Another person's caress is one of the most powerful of all emotional social signals. How much the primary somatosensory cortices (SIs) participate in processing the pleasantness of such social touch remains unclear. Although ample empirical evidence supports the role of the insula in affective processing of touch, here we argue that SI might be more involved in affective processing than previously thought by showing that the response in SI to a sensual caress is modified by the perceived sex of the caresser. In a functional MRI study, we manipulated the perceived affective quality of a caress independently of the sensory properties at the skin: heterosexual males believed they were sensually caressed by either a man or woman, although the caress was in fact invariantly delivered by a female blind to condition type. Independent analyses showed that SI encoded, and was modulated by, the visual sex of the caress, and that this effect is unlikely to originate from the insula. This suggests that current models may underestimate the role played by SI in the affective processing of social touch.affective touch | sexual selection | gender | crossmodal perception | hot cognition

Placebo improves pleasure and pain through opposite modulation of sensory processing

“…This modulation affected cortical targets of both myelinated Afibers (SI and SII) and unmyelinated C-fibers (pINS). This result is consistent with recent findings that modulation of touch affect is reflected in both pINS and SI (14,31).…”

“…Manipulation of people's beliefs about the price of a wine (11), the amount of fruit in a sweet drink (12), the richness of a skin cream (13), and who is caressing them (14) alters the experienced pleasantness of these stimuli.…”

Encoding of Touch Intensity But Not Pleasantness in Human Primary Somatosensory Cortex

“…Despite the evidence that touch pleasantness is processed outside of S1, several recent studies challenge this model, showing correlations between ratings of touch pleasantness and activation of S1 (though in opposite directions; McCabe et al, 2008;Gazzola et al, 2012). These studies demonstrate possible modulation of S1 by social context, but contain confounds related to attention and motivation and do not demonstrate the causal necessity of S1 in the perception of touch pleasantness.…”

Emotion: The self-regulatory sense

“…Of course, as we have seen, the self-regulatory sensory network begins in the "branes" of all cells, including the skin cells that still bound and contain the human systemhence the classic Galvanic Skin Response (GSR) measure of emotional arousal as well as the emotive component of social touch. 246 Likewise, the coupling between positive and negative feedback is evident in the reciprocal, bi-directional, interactions between the right and left hemispheres of the brain, 247 between the brain and heart, and between the sympathetic and parasympathetic branches of the autonomic nervous system. Indeed, the vagal nerve mediates bottom-up emotional sensitivity (high stress "reactivity") as well as top-down emotion regulation (faster recovery), both of which are associated with high vagal tone.…”