An overview of papers published in affective touch from the view of early-career researchers.

Contributors: Laura Crucianelli

April 2021, Laura Crucianelli

C-tactile afferents finally show up on non-hairy skin!
Previous studies showed that CTs are abundant in hairy skin and are thought to code gentle, stroking touch that signals positive affective interactions. CTs have never been described in human glabrous skin, yet. Watkins and colleagues showed the first evidence of their existence on the non-hairy skin of the hand, albeit at a relatively low density. The authors suggest that CTs in the glabrous skin may provide modulatory reinforcement of gentle tactile interactions during touch using the hands. Time to update all our papers in preparation!

Watkins RH, Dione M, Ackerley R, Backlund Wasling H, Wessberg J, Loken LS (2021). Evidence for sparse C-tactile afferent innervation of glabrous human hand skin. Journal of Neurophysiology, 125(1): 232-237.

 

April 2021, Laura Crucianelli

Why do hugs feel so good?
The social touch hypothesis proposes that C-tactile fibers form a privileged pathway underlying social touch. The pleasantness percept has long been related to a slow, caress-like touch. Here, Case and colleagues propose that deep pressure constitutes another important form of social touch. Their results suggest that the brain activity recorded during deep pressure is comparable to the one elicited by classic CT-optimal stroking, involving S2, SMG and insula. Thus, deep pressure (such as the one experiences in hugs and massages) may constitute another social touch pathway signalling the close proximity of conspecifics.

Case LK, Liljencrantz J, McCall MV, Bradson M, Necaise A, Tubbs J, Olausson H, Wang B, Bushnell MC (2021). Pleasant deep pressure: expanding the social touch hypothesis. Neuroscience, in press.

 

April 2021, Laura Crucianelli

The insula is necessary for the perception of tactile pleasantness
Kirsch and colleagues report the first human lesion study on the perception of C-tactile touch in right hemisphere stroke patients (N = 59). The results show that lesions in the right posterior and anterior insula reduce tactile, contralateral and ipsilateral pleasantness sensitivity, respectively. These findings provide important insight into the areas involved in the central processing of tactile signals associated with the peripheral activation of CT afferents and corroborate previous imaging studies regarding the role of the posterior insula in the perception of affective touch.

Kirsch LP, Besharati S, Papadaki C, Crucianelli L, Bertagnoli S, Ward N, Moro V, Jenkinson PM, Fotopoulou A (2020). Damage to the right insula disrupts the perception of affective touch. elife, 9, e47895.