[The interrelationship of pain and temperature reception in human skin]

Local cooling (14-16 degrees C) and warming (40-42 degrees C) of different crus areas or healthy volunteers have been studied for their effect on pain sensitivity. The latter was estimated by means of the tibialis anterior flexor reflex (FR) and EMC-recording. It was established that changes in FR parameters depended not on the thermostimulus modality, but on its position. The FR was enhanced when the warm or cold stimulus was applied over the ipsilateral tested flexor muscle, and it was mainly inhibited when the thermostimulus was over the extensor or contralateral flexor. An assumption is made that the loss of the temperature modality is caused by convergence of temperature and pain information to the spinal interneurons of the "bimodal type". These neurons change their impulse activity under the effect of both temperature modalities. Different reactions of FR on thermostimulation of different areas of the crus are explained by the locomotor generation control of afferent information.