Abstract
Touch has an affective dimension, conveyed through low-threshold
mechanoreceptors known as C-tactile (CT) afferents, which are activated
by gentle, caress-like contact. While there is evidence that these
fibers modulate nociceptive input, their influence in the processing of
other somatosensory afferent activity remains largely unknown. In this
study, we explored how slow brushing (CT-optimal stimulation) modulates
somatosensory evoked potentials (SEPs) compared to vibration and no
touch in 30 healthy participants. Our results did not show differences
across conditions in the amplitude of early SEPs recorded over the
somatosensory cortex (N20, P25, N30, and P45). However, a reduced
frontocentral P150 SEP component was observed during slow brushing
compared to the other conditions. This suggests that early cortical
processing of somatosensory information is not affected by brushing.
Nonetheless, the reduced P150 amplitude indicates that CT-optimal touch
may influence both nociceptive afferents and somatosensory input through
the lemniscal system, possibly engaging brain areas involved in
attentional and cognitive processing.