The influence of visual experience and cognitive goals on spatial representations of nociceptive stimuli
Localizing pain is an important process as it allows detecting which part of the body is being hurt and identifying in its surrounding which stimulus is producing the damage. Nociceptive inputs should therefore be mapped according to both somatotopic (\"which limb is stimulated?\") and spatiotopic representations (\"where is the stimulated limb?\"). Since the limbs constantly move in space, the brain has to realign the different spatial representations, for instance when the hands are crossed and the left/right hand is in the right/left part of space, in order to adequately guide actions towards the threatening object. Such ability is thought to be dependent on past sensory experience and contextual factors. This was tested by comparing performances of early blind and normally sighted participants during nociceptive temporal order judgment tasks. The instructions prioritized either anatomy (left/right hands) or the external space (left/right hemispaces). As compared to an uncrossed hands posture, sighted participants performances were decreased when the hands were crossed, whatever the instructions. Early blind participants performances were affected by crossing the hands only during spatial instruction, but not during anatomical instruction. These results indicate that nociceptive stimuli are automatically coded according to both somatotopic and spatiotopic representations, but the integration of the different spatial reference frames would depend on early visual experience and ongoing cognitive goals, illustrating the plasticity and the flexibility of the nociceptive system.