Modulation of radial blood flow during Braille character discrimination task

Abstract

Purpose: Human hands are excellent in performing sensory and motor function. We hypothesized that blood flow of the hand are dynamically regulated by sympathetic outflow during concentrated finger perception. To identify this hypothesis, we measured radial blood flow (RBF), radial vascular conductance (RVC), heart rate (HR), and arterial blood pressure (AP) during Braille reading performed under the blind condition in nine healthy subjects. The subjects were instructed to read a flat plate with raised letters (Braille reading) for 30 s by the forefinger, and to touch a blank plate as control for the Braille discrimination procedure.Results: HR and AP slightly increased during Braille reading but remained unchanged during the touching of the blank plate. RBF and RVC were reduced during the Braille character discrimination task (decreased by -46% and -49%, respectively).Furthermore, the changes in RBF and RVC were much greater during the Braille character discrimination task than during the touching of the blank plate (decreased by -20% and -20%, respectively). Conclusions:These results suggested that the distribution of blood flow to the hand is modulated via sympathetic nerve activity during concentrated finger perception.

Relationship between the changes in blood flow and volume in the finger during a Braille character discrimination task

“…We made flat plates with raised letters, as previously reported . The convexities (diameter: 3 mm, height: 1 mm) on the plates were arranged according to Braille code.…”

“…Recently, we have reported that radial blood flow, measured using an ultrasound Doppler system, is reduced via sympathetic nerve activity during a Braille character discrimination task . This decrease in radial blood flow during the Braille discrimination task may be followed by fluctuations in fingertip skin blood flow (SBF) and finger volume (FV), which in turn results in the deformation of the cutaneous tissues.…”