Objective: Near-infrared spectroscopy (NIRS) is commonly used to investigate continuous changes of brain activation and has excellent time resolution. Verbal fluency task (VFT) is widely used as a neuropsychological test of frontal lobe function. The aim of this study was to investigate normal developmental change in frontal lobe function during VFT performance using multi-channel NIRS, specifically focusing on oxygenation hemoglobin (oxyHb) changes.
Methods: The subjects were 9 adults and 37 childrens who were all healthy right-handed volunteers. Children were divided into four age groups (group A, 6-8 years; group B, 9-11 years; group C, 12-14 years; group D, 15-18 years). The [oxyHb] changes were measured with 22 channels of NIRS during VFT. We defined the frontopolar region as the region of interest for analysis, and calculated the Z-score to compare the data between groups.
Results: The task performance changed with age. There were significant differences between group A and other groups. The Z-score of [oxyHb] also significantly increased with age, when comparing adults to groups A and B. The task performances decreased with time in all groups. In contrast, [oxyHb] only continued to increase in the adult group.
Conclusion: The verbal retrieval functions begin to mature in early adolescence and continue to grow up to adulthood.
Keywords: Development; Frontal lobe function; Near-infrared spectroscopy; Retrieval; Verbal fluency task.
Copyright © 2014 The Japanese Society of Child Neurology. Published by Elsevier B.V. All rights reserved.