Seeking pleasant touch: neural correlates of behavioral preferences for skin stroking

摘要: Affective touch is a dynamic process. In this fMRI study we investigated affective by exploring its effects on overt behavior. Arm and palm skin were stroked with soft brush at five different velocities (0.3, 1, 10, 3, 30 cm s(-1)), using novel feedback-based paradigm. Following stimulation in each trial, participants actively chose whether the caress they would receive next trial be same speed ("repeat") or ("change"). Since preferred stroking speeds should sought greater frequency than non-preferred speeds, paradigm provided measure of such preferences form active choices. The implemented respect to differential subjective pleasantness ratings elicit healthy subjects, intermediate (1, 3 s(-1)) considered more pleasant very slow fast ones. Such linearly correlate changes mean firing rates unmyelinated low-threshold C-tactile (CT) afferent nerves skin. Here, gentle, optimal for activating CT-afferents not only affected behavioral choices, but engaged brain regions involved reward-related behavior decision-making. This was case both hairy arm, where CTs are abundant, glabrous palm, absent. These findings provide insights central mechanisms underlying perception touch, indicate that seeking involves value-based neural processing ultimately reflected preferences.