Biology subjects

Trotter, P. D.

Publications and source records attributed to Trotter, P. D..

2 recordsLinked to original sources

bioRxiv2026

The influence of force on the encoding and perception of affective touch

Stroking touch has been shown to be most pleasant at intermediate velocities of 1-10 cm.s-1, which relates well to the activity of C-low threshold mechanoreceptors (C-LTMRs), also called C-tactile afferents in humans, that have been implicated in encoding positive affective touch. This well-established finding has been demonstrated at gentle stroking forces (typically 0.4 N peak normal force), yet few studies have investigated the effect of force on the perception of stroking touch or on the activity of C-LTMRs. Presently, we investigated the pleasantness and intensity of stroking touch (0.3, 1, 3, 10, 30 cm.s-1) at different forces (0.2, 0.4, 0.8, 1.2, 1.6, 2.0 N) on hairy forearm skin and compared this to responses from C-LTMRs during stroking touch at the same velocities, but over fewer forces (0.05, 0.4, 1.5 N). We found significant effects of stroking velocity and force for both tactile pleasantness and intensity ratings. Pleasantness showed the typical inverted-U shaped relationship over stroking velocities, but this was modified by force: higher forces significantly decreased pleasantness at faster velocities. Conversely, tactile intensity increased linearly with both increasing velocity and force. Recordings from seven C-LTMRs showed that their firing frequency changed with stroking velocity, but that they were strongly modulated by force. Overall, we demonstrate the profound effect that force has on the perception of stroking touch, where tactile pleasantness and intensity appear to be a multi-faceted construct that are related to C-LTMR and A{beta}-LTMR activity, respectively, but that the firing in individual mechanoreceptor populations cannot fully account for percepts.

neuroscience↗

bioRxiv2020

Topical heterogeneity in affective touch: Does it impact body image?

Recent evidence suggests that altered responses to affective touch - a pleasant interoceptive stimulus associated with activation of the C-Tactile (CT) system, may contribute to the aetiology and maintenance of mental conditions characterised by body image disturbances (e.g., Anorexia Nervosa). Here, we investigated whether tactile pleasantness and intensity differ across body sites, and if individual differences in dysmorphic appearance concerns and body awareness might be associated to touch perceptions across body sites. To this end, we measured perceived pleasantness and intensity of gentle, dynamic stroking touches applied to the palm, forearm, face, abdomen and back of 30 female participants (mean age: 25.87{+/-}1.17yrs) using CT-optimal (3 cm/s) and non-CT optimal (0.3 and 30 cm/s) stroking touch. As expected, participants rated CT-targeted touch as more pleasant compared to the two non-CT optimal stroking touch at all body sites. Nevertheless, CT-targeted touch applied to the abdomen elicited the lowest pleasantness ratings compared to all other body sites and to the two non-CT optimal stroking touch. Individual differences in body awareness and dysmorphic concerns significantly predicted preference for CT-optimal over non-CT optimal stroking touch applied to the forearm and the back. These findings begin to elucidate the link between CT sensitivity, dysmorphic appearance concerns and body awareness, which may have implications for future research looking to inform early interventions. Addressing impaired processing of affective interoceptive stimuli, such as CT-targeted touch, may be the key to current treatment approaches available for those populations at risk of disorders characterised by body image disturbance.

neuroscience↗