Effect of temperature on sensitivity of the finger

Subjects reported the detection of impacts from objects falling upon the ball of the finger. At a given point on the skin a falling weight of 1 mg might be detected after falling 10 mm, and twice the weight would then be detected after falling 5 mm. Droplets of mercury expelled by a Scholander micrometer burette afforded one series of measurements. On 6 days for one subject the threshold of perceptible impact was least at about 35 C. It increased rapidly as the finger was cooled with Q10 = 4.5 from 35 C to 30 C and with Q10 = 2.5 from 30 C to 20 C. In five other subjects falling droplets of mercury and falling steel ball bearings showed the threshold for detection to increase rather regularly for each individual as the skin was cooled, but on various individual rates with Q10 from 2 to 10. The variation in threshold sensation for impact with temperature raises the question of how heterothermous organisms can estimate and react suitably to some peripheral conditions which must be assessed on absolute scales by means of neural processes that are so thermolabile.

impact tests; sensitivity of finger skin; thermolabile sensation and integration; nervous integration

Submitted on May 20, 1963