Dysynchiria: watching the mirror image of the unaffected limb elicits pain on the affected side

The somatosensory system relays sensory information from the skin, mucous membranes, limbs, and joints. Somatosensation is more familiarly known as the sense of touch. A typical somatosensory pathway includes three types of long neurons: primary, secondary, and tertiary. Primary neurons have cell bodies located near the spinal cord in groups of neurons called dorsal root ganglia. The sensory neurons of ganglia innervate designated areas of skin called dermatomes.

Synesthesia is a remarkable condition where stimulation of one sensory or cognitive pathway leads to automatic, involuntary experiences in a second sensory or cognitive pathway. People with synesthesia experience a blending or crossing of their senses, such as sight and sound, leading to cross-modal sensations. In this condition, the stimulation of one sense, such as hearing a number or musical note, triggers an experience of another sense, like sensing a specific color, taste, or smell. People...