Nurturing touches in early life are important for a healthy neuronal development. It protects against social isolation and mental health struggles in adult life. But not all of us get a good start in life. C-Tactile afferents are neurons that sense soft touch that is important in social bonds and positive reinforcement for example with a clap on the back. But people that have been neglected as children have a very different experience.
Can babies discern affective touch?
When babies are born their nervous system is not completely developed. But the structure of the C-tactile afferents is evolutionarily much older than most of our nervous system. Scientists tested rather two month old babies would be able to distinguish slow, C-tactile afferent sensitive touch from faster stroking. And indeed they can. Their brain doesn’t respond exactly the same way as in adults. However, particularly in the part of the brain that is termed Insula the signal that baby receive from slow touch is very mature. The Insula is prominently involved in the autonomic nervous system that deals with many of the in voluntary processes of our organs e.g. heart rate and digestion. Slow touch also induces a signal in the temporal cortex in babies. It is associated with processing emotions and disturbances in sleep (1).
How is soft touch received in people with adverse childhood experiences?
So, we have established that babies can already discern affective touch via the C-tactile afferents. Some children however grow up with little to no affective touch. This can lead to difficulties in processing emotions and poor mental health. As I suggested in BRUSH off- feelings of OSTRACISM, I thought I could counteract the miserable state my parents leaved me in by picking up a fluffy make-up brush and give myself some comfort and positive reinforcement. But I noticed that specially on my arms I find the sensation very uncomfortable indeed. And looking further into the literature I found scientific evidence to explain that phenomenon.
A more recent publication examined care-leavers perception of touch. In a first questionnaire they confirmed that care-leavers are more likely to have been exposed to adverse childhood experiences compared to the control group. Then they asked the care leavers and non-care-leavers to rate the pleasantness of touch. The touch was administered with a soft brush on their forearms. And indeed the group of care leavers ranked the touch resonating with C-tactile afferents at 3 cm/s less pleasant than the control group (Figure 1) (2).
What I am experiencing when I brush over my forearm is not less pleasant. It is definitely very unpleasant. I want to scratch myself to get rid of that sensation. I am interested in more research on this topic in the future. C-tactile afferents in general but particularly how it is different in people with adverse childhood experiences. Do we have more or less of these receptors then people that grow up in typical family environments? Are they different in structure or is the read out in our brains different? Did I learn soft touch is dangerous? And most importantly is neuroplasticity sufficient to reverse this divergence?
(1) Affective and non-affective touch evoke differential brain responses in 2-month-old infants (2018) E. H. Jönsson, K. Kotilahti, J. Heiskala, H. Backlund Wasling, H. Olausson, I. Croy, H. Mustaniemi, P. Hiltunen, J. J. Tuulari, N. M. Scheinin, L. Karlsson, H. Karlsson, I. Nissilä
(2) Childhood Adversity and Affective Touch Perception: A Comparison of United Kingdom Care Leavers and Non-care Leavers (2020) S. L. Devine, S. C. Walker, A. Makdani, E. R. Stockton, M. J. McFarquhar, F. P. McGlone, P. D. Trotter
