Somatosensation, the sense of touch, and interoception, the perception of sensations from inside the body are necessary for the establishment of the bodily self. Rebecca Böhme, research fellow at Center for Social and Affective Neuroscience, and Håkan Olausson, professor in Clinical Neuroscience, are investigating how neurotypical volunteers, i.e., people without a psychiatric diagnosis, and participants with a psychiatric disorder are experiencing the self through touch. This flagship project is a composition of several projects within the same area. They have examined participants with attention hyperactive deficit disorder (ADHD), Anorexia nervosa, autism and schizophrenia.
When people who are close to us touch us, certain messenger substances are released in our body, which tells us that we are safe and not alone. This makes us feel less stressed, anxious, or worried.
- The self – other differentiation is very important, not just in relation to touch, but very broadly. We have to be able to know that this is me and that is another person, Rebecca Böhme explains. How does the brain understand that certain signals are coming from me touching myself and not from another person? This relates to the idea that there is a minimal self, which means basically the perception of the own body as “self”.
- We all need this minimal self, and it develops very early in life, already in the womb. The other senses as for example visual and auditory are lagging behind in development. Therefore, we think that the tactile sense is a very interesting sense to look at, when we want to understand the self – other distinction. We are specifically interested in the context of psychiatric disorders with dysfunctions in the self-domain, Rebecca continues.
For autism e.g., there seems to be a stronger self – other distinction. People with autism have clearer borders of themselves. Everything other is further away and that could explain lower level of empathy abilities.
In case of anorexia on the other hand, there seems to be a reduced perception of the self – other distinction. Patients often think of themselves as bigger than they are. This group of participants generally has a skewed perception of their own body and where the body ends. - They often have the sensation for example, when sitting on a chair that their own body overflows the chair, Rebecca says.