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Biomedical subjects

A M Prestrude

Publications and source records attributed to A M Prestrude.

13 recordsLinked to original sources

Auditory imprinting in domestic chicks during tonic immobility.

In present study we attempted to determine whether the characteristic unresponsiveness of animals during tonic immobility is due to sensory or motor inhibition. Specifically, we exposed domestic chicks to an auditory imprinting stimulus during tonic immobility. Seventy-five White Leghorn chicks were tested in 1 of 5 conditions: (1) immobilized and imprinted; (2) restrained but not immobilized, and imprinted; (3) imprinted only; (4) immobilized but not imprinted; and (5) neither immobilized nor imprinted. Chicks in the 1st 3 groups all imprinted to the same degree in that they did not differ in median run times in a straight alley with the imprinting stimulus. These results demonstrate that chicks do process auditory stimuli during tonic immobility and the reduced responsiveness observed during tonic immobility is due mainly to motor inhibition.

Acoustic Stimulation↗

Effect of skin surface temperature on localization error and two-point threshold.

The average localization error and two-point threshold were determined from 9 subjects at 5 skin temperatures on the volar forearm. The temperatures were physiological zero (31 degrees--32 degrees C), 19 degrees C, 25 degrees C, 38 degrees C, and 44 degrees C. Localization error was not significantly affected by skin surface temperature. This was verified on palm and forehead locations. The two-point threshold was increased by skin surface temperatures above physiological zero and decreased by skin surface temperatures below physiological zero. These results are consistent with a previous report of similar changes in punctate pressure sensitivity with varied skin surface temperatures. Such cross-model effects are considered in terms of cutaneous sensory mechanisms combining broad receptor specificity and subsequent coding of information by patterns of neural impulses.

Humans↗

Cutaneous cross-modal interactions: variations in punctate pressure sensitivity with skin surface temperature.

We determined the effects of adapting the skin surface to temperatures 3 degreees C, 8 degrees C, or 12 degrees C above and below physiological zero for 0, 2, 5, 10, 15, or 30 min on punctate pressure sensitivity. Temperatures above physiological zero reduced punctate pressure sensitivity and temperatures below physiological zero enhanced punctate pressure sensitivity. As the skin adapted to warmth, punctate pressure sensitivity increased suggesting a cross modal adaptation effect, however there was no indication of a decrease in punctate pressure sensitivity as the skin adapted to cooling. The results are considered to be consonant with a system of mechanoreceptors which also respond to temperature changes and a system in which there are points of convergence in the somesthetic pathways at which pressure and temperature information interact and are integrated.

Adaptation, Physiological↗

The relation of warmth and pain thresholds to skin pigmentation.

Thermal sensitivity increases with skin pigmentation. Absolute thresholds for warmth and pricking pain decreased as skin color increased for 13 Caucasian, 3 Mexican, and 4 Negro subjects. These data replicate and extend a previous psychophysical study of pain sensitivity and are compared with spectrophotometric data from excised skin. The results are considered to be potentially significant for the existence of a dermal light sense.

Hot Temperature↗