Influence of sustained cognitive loading on finger circulatory and thermoperceptual responsiveness to localized cooling.

Abstract

We examined whether finger vasomotor and thermoperceptual responses to local cooling would be modulated by sustained cognitive loading. Finger temperature, circulatory (i.e., cutaneous vascular conductance, CVC) and perceptual responses were monitored, in twelve healthy men, during and after a 30-min hand-immersion in 8°C-water, performed either immediately after a 60-min continual execution of a cognitive task (cognitive→cold trial), or during the simultaneous performance of the cognitive task (cognitive+cold trial). Subjects' responses were compared with those obtained in a control cold-provocation trial, wherein they watched an emotionally-neutral documentary. The cognitive task temporarily enhanced the perceived levels of mental effort and fatigue in both intervention trials. During cooling in the cognitive→cold trial, the area under the curve (AUC) for finger CVC was enhanced [49(23) PU･mmHg^-1･min vs. control: 36(22) PU･mmHg^-1･min], the cold-induced increase in mean arterial pressure was blunted [2(4) mmHg vs. control: 8(4) mmHg] (P<0.01), and the thermal discomfort was alleviated [2.2(0.5) vs. control: 2.5(0.7); P=0.05]. In the cognitive+cold trial, no intertrial differences were noted during the cold-water immersion (P≥0.28), but AUC for finger CVC was augmented during the last part of the rewarming [29(12) PU･mmHg^-1･min vs. control: 24(11) PU･mmHg^-1･min; P=0.05]. Present findings demonstrate that (i) in moderately mentally-fatigued individuals, finger cold-induced vasoconstriction is transiently attenuated, and thermal discomfort is mitigated, and (ii) superimposition of cognitive loading on cold stress does not alter finger vasoreactivity or thermosensitivity during cooling, but facilitates reperfusion following cooling.