Apparatus for determining in vivo response to thermal stimulation in an unrestrained subject

In a high sensitivity apparatus for determining the in vivo response to thermal stimulation in an unrestrained subject within a predetermined space which permits the selective application of radiant heat to a predetermined situs of the subject by means of a light beam, the combination comprising

• means for measuring time;
• movable means for generating a light beam;
• means for detecting said light beam, said detecting means being positioned so that it can detect the withdrawal of the situs from the path of said light beam and said detecting means also being isolated from said light beam generating means;
• means for stopping said time measuring means, and said light beam generating means and for inactivating said detecting means, all said means being electrically interconnected, said stopping means being automatically activated by said detecting means upon situs withdrawal;
• means for simultaneously starting said time measuring means and said light beam generating means and for activating said detecting means, all said means being electrically interconnected, whereby when said light generating means is aimed at the predetermined situs and positioned at a distance effective to locally provide radiant heat to said situs and said starting means is activated, the light beam elicits from said subject after a latency time period a spontaneous situs withdrawal response thereof which is detected by said detecting means, said time measuring means, said generating means, said detecting means, said stopping means and said starting means being part of an electrical circuit which is to be connected to a power source prior to use.