The nervous regulation of the sweating apparatus of the human skin, and emotive sweating in thermal sweating areas

Abstract

Observations on the neural regulation of the human sweat apparatus may help to clarify two outstanding problems concerning the functioning of the skin. It has been known since the work of Kuno andhis school (1956) that the emotive type of sweating is confined to specific area-s of the skin, palms, soles, axillae and limited parts of the face. These commence sweating possibly within a second after the application of a stimulus, such as mental arithmetic, discussion of an embarrassing topic, or physical exercise. Other areas of the skin surface do not show any trace of sweating in response to such stimuli at normal ambient temperatures up to 260 C, or higher, in most individuals. The responses to thermal stimuli, however, show a converse relationship. The general body surface responds primarily to thermal stimulation. When the ambient temperature around the subject is raised at a certain point there is a sudden onset of sweating. The emotive sweating areas, palm and sole, commence sweating later, and at a higher temperature than the other parts of the body.The sweat response of the emotive areas is accompanied by skin electrical changes, extensively used in psychological studies as a measure of arousal activity, though the exact nature of the physical relation between sweating and these electrical events has not yet been clarified. At high ambient temperatures, e.g. above 30°C, emotively induced sweating is seen on the general body surface (Kuno, 1956). The observations to be described here provide information about the nature of the mechanism causing this change in the sweating behaviour of the body surface.The work of Fox & Hilton (1958) on the control of blood flow to the skin has demonstrated the importance of the sweat mechanism in vasodilatation. These experiments showed that an enzyme appeared to be released in the sweat itself, causing the formation of bradykinin in the skin, which then brought about vascular dilatation by direct action. However, it was noted by Fox & Hilton (1958) that there was a small discrepancy between the incidence of vasodilatation and sweating. Vascular dilatation occurred

The regional distribution of emotional sweating in man

“…If the theory of Kuno (1956) and Kennard (1963) is correct, the emotional sweat response of areas other than the hands and feet at 26°C might be expected to be much less than that at 290 C. However, highly significant responses were observed from the hands and feet and from the rest of the body at both temperatures. There was no significant difference between the responses of either region at 260 C and their response at 290 C. It therefore seems unlikely that the skin of the rest of the body can respond to emotional stimuli only when close to or above the thermal sweating threshold.…”

“…The local methods of sweat estimation employed by McGregor (1952), Kuno (1956) and Kennard (1963) may have contributed to their failure to detect emotional sweat responses from the limbs and trunk of subjects below the thermal threshold since these areas have comparatively low sweat-gland densities. Differences in environmental conditions and strength of emotional stimuli employed may also help to account for apparent discrepancies between their results and the present observations.…”

Thermal Influence on Palmar Sweating and Mental Influence on Generalized Sweating in Man

“…Thus, sweat response to mental stimuli may appear on the general body surface only when close to or above the thermal sweating threshold. Even in a temperate environment, however, neural impulses for thermal sweating still reach the sweat glands and mental effects can be visualized on a focal area where local sweating has been provoked by a suforific agent (KENNARD, 1963;OGAWA, 1970;OGAWA and BULLARD, 1972). Furthermore, a small number of functional sweat glands have been detected on the general body surface in a temperate environment (RANDALL, 1946;NAKAYAMA and ARIMURA, 1955), and it has also been reported that there are no significant regional differences in sweat responses to emotional stimuli within the comfort zone (ALLEN et al, 1973).…”

“…As for the mechanism underlying such regional differences , however, explanations are controversial among investigators (KUNO, 1956;KENNARD, 1963;NAKAYAMA , 1969).…”

Psychological Sweating: A Systematic Review Focused on Aetiology and Cutaneous Response

“…palms and soles) [53]. However, more compelling data support the notion that emotion-evoked sweating is not limited to particular regions of the body but is a generalised phenomenon, although such sweating (or corresponding electrodermal activity) may only be visible on the palms, soles, axilla and face at normal room temperatures [40,54,55,56]. Given the regional differences in sweat gland density outlined previously, it is possible that measurable sweat responses are more readily obtained from the palms, feet and axilla, where sweat glands are more numerous compared to other body sites.…”