Cognitive activity and cutaneous blood flow

Serial subtraction and multiplication problems were performed orally by 21 healthy human subjects during two three-minute periods separated by a 22-minute rest interval. During the period of mental activity, cutaneous blood flow in the finger fell to 59%, digital cutaneous pulse pressure fell to 62%, and heart rate increased by 24% of the subjects' initial baseline values. Cutaneous blood flow in the malar region did not change. Because vasomotor control of the finger skin is principally vasoconstrictor and that of the malar area vasodilator, these results suggest that mental activity unrelated to obvious stress may provoke changes in cutaneous blood flow in areas controlled by sympathetic vasoconstrictor fibers. Simultaneous changes in digital cutaneous blood flow, digital cutaneous pulse pressure, and heart rate indicate an autonomic-mediated effect.