PROCESSI DI COSTITUZIONE DEL SÉ E DELL’INTERSOGGETTIVITÀ
NEI CASI DI MIRROR-TOUCH SYNESTHESIA

Giulio Galimberti

Mirror-touch synaesthetes (MTS) feel a touch on their own body when this touch is seen on another body. Synesthesia, more generally, refers to an automatic and involuntary neurophysiological condition where one attribute of the environment triggers a secondary experience that is not typically associated with the first. Two explanations known as the Threshold Theory and the Self-Other Theory have been proposed for the occurrence of MTS. The first one is based on the discovery of mirror neurons in the somatosensory cortex which is responsible for receiving tactile stimuli. Observing a person being touched typically activates the same neural areas involved in the first-person touch experience. Threshold theory explains the conscious experience of touching one’s body as exceeding a threshold of awareness due to mirror system hyperactivity. This explanation is in some ways incomplete. Individuals with MTS seem to have an atypical self-awareness. Comparing synaesthetes with non-synesthetic controls in Rubber Hand Illusion and Enfacement Illusion experiments shows increased malleability of bodily self-awareness in synaesthetes. However, these experiments show that it is possible to alter proprioceptive body maps in non-synesthetes. The sense of self thus emerges as a weaving process between exteroception and proprioception. Our self-awarenes comes from multisensory integration processes that are based on sensorimotor contingencies determined by our bodily engagement. The intersubjectivity assumed through the mirror system proposes that the bodily self is conditioned by the observed actions of others as it simulates them internally. Enactivism and embodiment theories can work together to provide a clearer account of MTS.