Mechanisms of Neuropathic Pain: Investigation by Contact Heat Evoked Potential

In order to clarify the normal components of thermal and painful evoked potentials by heat in normal subjects of both genders and different age group, to clarify the effect of specific anatomy in pain transduction, transmission and modification, and to establish the effect of peripheral nerve and their terminal free ending on the nociceptive transduction, the investigators will use heat stimulation on normal controls and patients with neurological diseases to clarify such issues.