Somatosensory Cortical Representation of Facial Nociception and Vibrotactile Touch Induced Analgesia

Abstract

Pain relief by vibrotactile touch is a common human experience. Previous neurophysiological investigations focused on spinal mechanisms in anesthetized animals. However, whether and how cortex, especially the primary somatosensory cortex (S1), is involved in this process in behaving animals remains unknown. Here I used awake behaving mice to study this touch induced pain relief. First, I discovered that vibrotactile reafferent signals from self-generated whisking significantly reduce facial nociception. Second, I showed that specific blocking of touch transmission from thalamus to barrel cortex (S1B) abolished whisking induced analgesia. Third, I developed a neuron extraction pipeline for 1-photon based calcium imaging and used in vivo imaging to show that tactile and noxious stimuli differentially activate S1B neurons. Lastly, I applied the intrinsic manifold analysis of S1B population activity to reveal that whisking pushes the transition of neural state induced by noxious stimuli towards the state encoding non-nocifensive actions. I concluded with an awake behaving mouse model for studying S1B touch induced pain relief, and that S1B contains nociceptive representations and integrates tactile and painful signals to enable touch mediated pain relief.