Brain processing of reward for touch, temperature, and oral texture

Abstract

Some of the principles of the representation of affective touch in the brain are described. Positively affective touch and temperature are represented in parts of the orbitofrontal and pregenual cingulate cortex in which other neurons represent the reward value of taste, olfactory, and/or visual stimuli. The orbitofrontal cortex is implicated in some of the affective aspects of touch that may be mediated through C fibre Touch afferents, in that it is activated more by light touch to the forearm (a source of CT afferents) than by light touch to the glabrous skin of the hand. Oral somatosensory afferents implicated in sensing the texture of food including fat in the mouth also activate the orbitofrontal and pregenual cingulate cortex, as well as the insular taste cortex. Top-down cognitive modulation of the representation of affective touch produced by word labels is found in parietal cortex area 7, the insula and ventral striatum. The cognitive labels also influence activations to the sight of touch and also the correlations with pleasantness in the pregenual cingulate/orbitofrontal cortex and ventral striatum.