SIR CHARLES SHERRINGTON, in 1903, during his investigation of the "scratch" reflex in dogs with transected spinal cords, used a heat lamp as a source of noxious stimuli.1 He observed that thermal radiation "applied locally to the skin of the reflexogenous zone suffices, if not merely 'warm' but 'hot' [to the hand], to at once provoke the scratch reflex." He also observed that a heated metal plate evoked the scratch reflex in the spinal dog only after it had reached the temperature of "85 C. or more." It was observed subsequently by other investigators that immersing the feet of paraplegic patients in ice water or hot water could evoke withdrawal movements but that these responses were variable and unpredictable.* However, the stimulus intensities required to evoke reflex withdrawal in animals and humans with transected spinal cords have not been adequately measured. Therefore, quantitated thermal stimuli were applied to the
BERLIN L, GUTHRIE TC, GOODELL H, WOLFF HG. STUDIES ON THE CENTRAL EXCITATORY STATE: Factors Responsible for the Variability of the Motor Response to Cutaneous Stimulation in Human Subjects with Isolated Spinal Cords. AMA Arch NeurPsych. 1954;72(6):764–779. doi:10.1001/archneurpsyc.1954.02330060100012
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