Photo Credit: Silver Place

The following is a summary of “Disentangling the spinal mechanisms of illusory heat and burning sensations in the thermal grill illusion,” published in the October 2024 issue of Pain by Mitchell et al.  

The thermal grill illusion (TGI), a phenomenon of warm and cold temperatures on the skin, produces a burning sensation leading to pain with harmless stimuli.   

Researchers conducted a retrospective study to examine the role of the spinal cord in TGI.    

They investigated 80 participants by applying heat and cold stimuli to dermatomes, areas of skin innervated by a single spinal nerve, mapping onto either adjacent or nonadjacent spinal segments. During the TGI, enhanced warm and burning sensations were observed when cold and warm stimuli were confined to the same dermatome.   

The results showed the spatial organization of warm and cold stimuli within and across dermatomes affected the perception of the TGI. Perceived warmth and burning intensity increased when the cold stimulus was applied to a segment that was more caudal to the warm stimulus. In contrast, perceived cold decreased as compared to the opposite spatial arrangement.  

They concluded the perception of TGI is enhanced when cold afferents are projected to spinal segments caudally compared to warm afferents, suggesting distinct interactions of sensory pathways based on the segmental arrangement of afferent fibers.   

Source: journals.lww.com/pain/abstract/2024/10000/disentangling_the_spinal_mechanisms_of_illusory.24.aspx