Activation of the Prefrontal Cortex during the Wisconsin Card Sorting Test as Measured by Multichannel Near-Infrared Spectroscopy

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Abstract
The Wisconsin Card Sorting Test (WCST) is a neuropsychological test to evaluate the function of the prefrontal cortex (PFC). However, inconsistent results have been reported concerning whether this task activates the PFC symmetrically or asymmetrically. To investigate the brain activation in the PFC during the WCST, we examined blood oxygenation changes of healthy subjects by using multichannel near-infrared spectroscopy (NIRS). Subjects were 32 healthy volunteers, 18 males and 14 females. The WCST was administered using a computerized version, and the hemodynamic changes of the PFC during the WCST were measured by a 24-channel NIRS system. A bilateral increase in oxygenated hemoglobin (oxyHb) was observed in the PFC in 20 subjects during the WCST. However, 5 subjects showed predominant activation on the left side and 3 subjects one on the right side. No oxyHb change was observed in 4 subjects, although they had good performances in the WCST. These results directly confirmed that the PFC was activated during the WCST in vivo by using the optical technique and suggested that the distribution of the activation in the PFC is different among healthy individuals.