Thermosensory cues influence bodily awareness

The skin continuously relays thermosensory signals, which are crucial in maintaining homeostasis and ensuring survival [1].This information, indeed, provides cues about the temperature of the bodyinsulated superficial layer and offers feedback to the central thermoregulatory system [2].Interestingly, cutaneous thermosensory information may also contribute to higher-level cognitive constructs, such as bodily self-awareness.Bodily self-awareness refers to the conscious feeling that sensory and motor experiences are intrinsically linked to the self, contributing to a coherent and unified identity.Such a multifaceted concept encompasses the feeling of one's own body as belonging to oneself and the feeling that a given body part belongs to one's body (i.e. the sense of ownership).Traditionally, the sense of ownership has been ascribed to the integration of multiple sensory inputs from internal and external sources, such as touch, vision, proprioception, and motor signals.Emerging evidence also highlights the role of skin temperature and thermoception in this process.Our new study [3] investigated the role of thermosensory signals in bodily self-awareness in a clinical population presenting with Disturbed Sensation of Ownership (DSO) affecting the left plegic limb following a right-hemisphere stroke.Patients with DSO may not recognize their paralyzed hand as part of their body, often denying ownership and attributing it to someone else, such as a familiar person or medical staff.We examined 45 patients with right-hemisphere brain damage, categorized into three groups: those with both hemiplegia and DSO for the left hand, those with hemiplegia but no DSO, and those without hemiplegia or DSO.We assessed baseline hands and feet skin temperature and hand thermoception for warm and cold stimuli, revealing that patients with DSO for their left hand, compared to the other two groups, exhibited lower hairy skin temperatures of both left and right hands.Interestingly, feet skin temperature was equal between the groups.Additionally, we demonstrated impaired thermoception (involving both warm and cold thermal stimuli) on their affected (left) hand.To further explore the neural basis of these findings, we applied advanced neuroimaging techniques, including voxel-based lesion-symptom mapping (VLSM) and connectome-based lesion-symptom mapping (CLSM).These techniques provide a powerful tool to examine how specific brain lesions or disruptions in structural connectivity between brain regions relate to behavioral impairments.By mapping damaged or disconnected brain regions to observed deficits, critical areas involved in specific functions can be identified (i.e.lower skin temperature and thermoception deficits).The VLSM analyses identified the right Rolandic Operculum and Insula as key regions associated with reduced hands temperature and impaired thermoception.A decrease in hairy skin temperature of both handscharacterizing patients with DSO -was linked to lesions in the right posterior insula, while deficits in thermoception of the left hand -found in patients with DSO-were associated with lesions in more anterior regions of the right insula.CLSM analyses further revealed that disruptions in bilateral parietal connections were linked to reduced hands temperature, while impairments in a right-lateralized thalamus-parietal network correlated with thermoception deficits of the left hand (see Figure 1).