Different neurological damage may alter the pain conduction systems centrally (spinothalamic pathway) or peripherally (small caliber sensory fibers A delta and C). The laser thermal stimulation selectively stimulates the pain pathways and generates nociceptive signals conveyed to the cortex. Registering these cortical responses constitute the technical laser nociceptive evoked potentials. If these tests are routinely used, their interpretation must remain cautious especially in the elderly.

Different neurological damage may alter the pain conduction systems centrally (spinothalamic pathway) or peripherally (small caliber sensory fibers A delta and C). The laser thermal stimulation selectively stimulates the pain pathways and generates nociceptive signals conveyed to the cortex. Registering these cortical responses constitute the technical laser nociceptive evoked potentials. If these tests are routinely used, their interpretation must remain cautious especially in the elderly. Normal values that are available have been obtained in young subjects. However, various studies have shown that the integration of nociceptive messages depended on age. The aim of this study was to establish normal values of nociceptive evoked potentials for each age group of 18 to 75 years.

Inclusion Criteria:

• major

Exclusion Criteria:

• Neurological history
• Neuralgia history (> 3 months)
• Pathology can cause neuropathy (unbalanced thyroid dysfunction, diabetes, kidney failure, chronic hepatitis, HIV ...)
• Dermatological disorder known type of Lucite or photosensitivity
• Medical treatment analgesic, psychotropic or anti-epileptic underway
• Toxic acquired in the last 72 hours (alcohol, cannabis, other toxic ...)
• Pregnant women
• Incapacitate to stand still
• Participation in another biomedical research in the field of pain in the three months prior to inclusion.