SOMATOSENSORY PERCEPTION IS TEMPORALLY MODULATED DURING MOVEMENTS TO SELF-TOUCH

Self-touch feels less intense than an identical touch delivered externally. This distinction arises because the brain predicts the somatosensory consequences of voluntary movements using a copy of the motor command. However, it remains unclear how these sensorimotor predictions influence somatosensory processing prior to the occurrence of self-touch. Focusing on the interval before the self-touch provides a unique opportunity to examine how sensorimotor predictions shape somatosensory perception and neural activity. We addressed this question through a series of experiments conducted across multiple studies. The participants moved their right hand to touch their left hand while receiving tactile stimulation on the left hand at different time points during the reaching movement. At the behavioural level, we quantified the perceived stimulus intensity, and at the neural level, we examine stimulus-related neural activity using magnetoencephalography (MEG). We showed that tactile stimuli were perceived as progressively weaker as the movement unfolded, reaching their lowest intensity at the moment of self-touch. Importantly, when the movements did not generate predictions of self-touch, this gradual attenuation of somatosensory perception was absent, highlighting the predictive nature of this process. Moreover, this temporal tuning of somatosensory perception was reduced when movements were performed without vision, indicating that multiple sensory modalities contribute to the predictive processes underlying somatosensory modulation during movements to self-touch. Finally, an ongoing MEG study is examining the neural correlates of these behaviourally observed effects. Overall, these findings comprehensively characterize how somatosensory perception is temporally modulated during movements to self-touch and underscore the predictive mechanisms underlying this phenomenon.