Functional near-infrared spectroscopy study of the neural correlates between auditory environments and intellectual work performance.
INTRODUCTION
Many people spend a considerable amount of time performing intellectual activities within auditory environments that affect work efficiency. To investigate auditory environments that improve working efficiency, we investigated the relationship between brain activity and performance of the number memory task in environments with and without white noise using functional near-infrared spectroscopy (fNIRS).


METHODS
Twenty-nine healthy subjects (aged 21.9 ± 1.4 years) performed the number memory task in both the white noise and silent environments. Cerebral blood flow changes during the task were measured using an ETG-7100 fNIRS system (Hitachi, Ltd., Tokyo, Japan). The psychological states of the subjects were also estimated by subjective ratings of the pleasantness of the auditory environment. Then, they were divided into three groups based on their task scores. The differences in the cerebral blood flow (CBF) changes, functional connection strength, and the subjects' feelings of pleasantness to the noise between the subject groups were analyzed and discussed.


RESULTS
The first group felt that the white noise was pleasant, which strengthened the bilateral functional connections between the brain regions related to the memory task. Therefore, the subjects' task performance improved in the white noise environment. Although the second group felt that the white noise was uncomfortable, the frontal regions related to attention control were more activated in the white noise environment to sustain the task performance in the noisy environment. The third group felt that the white noise was unpleasant, and their CBF decreased in that environment, which was associated with deteriorated task performance.


CONCLUSIONS
Task performance was closely related to the subjects' feelings of pleasantness to the noise. The results of the analysis of the CBF changes and functional connectivity suggested that the effects of the white noise on brain activity differed among the three groups.
['Hiwa|Satoru|S|0000-0001-6547-626X', 'Katayama|Tomoka|T|', 'Hiroyasu|Tomoyuki|T|0000-0003-0730-7905']
D001288:Attention D001921:Brain D001931:Brain Mapping D002560:Cerebrovascular Circulation D005260:Female D006801:Humans D007564:Japan D008297:Male D009622:Noise D019265:Spectroscopy, Near-Infrared D000066477:Work Performance D055815:Young Adult
auditory environment intellectual work performance number memory task functional near-infrared spectroscopy (fNIRS) functional connectivity graph theoretical analysis