Application of depth-selective algorithm to brain function measurement

Abstract

A depth-selectivity filter has been proposed as an algorithm for suppressing skin blood flow in near-infrared optical brain function measurement. We apply this method to the measurement during the performance of Stroop GO/NO-GO task. Japanese red, blue, and white hiragana characters were presented in a random order. The subject pressed the button when the color letters did not match. The measurement area was the frontal forehead. 24 normal source-detector distance (SD) sensors and 6 short-source-detector distance (SSD) sensors were placed on the frontal forehead. Ten subjects were participated the experiments. The averaged oxygenated and deoxygenated hemoglobin concentration changes showed a similar tendency in the SSD and the SD channels and the skin blood flow is dominant. With the depth-selectivity filter, the changes in oxygenated and deoxygenated hemoglobin concentration showed anti-phase characteristics in the central part of the forehead. Thus, the influence of the skin blood flow seems to be reduced.