STUDIES IN TEMPERATURE SENSATION. III. THE SENSITIVITY OF THE BODY TO HEAT AND THE SPATIAL SUMMATION OF THE END ORGAN RESPONSES

Abstract

The authors detd. the amt. of radiant energy required to produce sensation when areas of different size and location on the body surface were exposed. The exptl. procedure allowed stimulation of any desired size of skin area. With the entire body exposed, the radiation rate which will just produce sensation was 0.00015 gm. cals/sq. cm/sec. The sensation was evoked in 3 sec. and the skin temp. change produced by this radiation was 0.003[degree]C. Surface areas as large as 200 sq. cm. (the face) were as sensitive as the entire body. The intensity of the stimulus necessary to evoke sensation increased as the size of the area stimulated was decreased. The spatial summation of end organ effects was studied. Areas on the forehead were found to sum-mate regularly and although 2 hands summated there was no summation between the hand and the forehead. The limit of sensibility of the body to thermal stimuli was set, by the threshold of the end organs rather than by the failure of spatial summation.