| Influence of skin blood flow on near-infrared spectroscopy signals measured on the forehead during a verbal fluency task. | |
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MedLine Citation:
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PMID: 21600294 Owner: NLM Status: Publisher |
Abstract/OtherAbstract:
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Brain activity during a verbal fluency task (VFT) has been the target of many functional imaging studies. Most studies using near-infrared spectroscopy (NIRS) have reported major activation in the frontal pole, but those using PET or fMRI have not. This led us to hypothesize that changes in the NIRS signals measured in the forehead during VFT were due to changes in skin blood flow. To test this hypothesis, we measured NIRS signals and the Doppler tissue blood flow signals in the foreheads of 50 participants. The measurements were performed while each participant produced words during two 60-s periods with an interval of 100s. In addition to a conventional optode separation distance of 30mm (FAR channels), we used a short distance - 5mm (NEAR channels) - to measure NIRS signals that originated exclusively from surface tissues. The oxygenated hemoglobin (oxyHb) concentration in the FAR and NEAR channels, as well as the Doppler blood flow signal, increased in a similar manner during the two periods of word production; the signal increase in the first period was twice as high as that in the second period. Accordingly, the mean changes in oxyHb concentration in the FAR channels were correlated closely with the changes in the NEAR channels (R(2)=0.91) and with the integrated Doppler skin blood flow signal (R(2)=0.94). Furthermore, task-related NIRS responses disappeared when we blocked skin blood flows by pressing a small area that covered a pair of optodes. Additionally, changes in the FAR channel signals were correlated closely with the magnitude of pulsatile waves in the Doppler signal (R(2)=0.92), but these signals were not highly correlated with the pulse rate (R(2)=0.43). These results suggest that a major part of the task-related changes in the oxyHb concentration in the forehead is due to task-related changes in the skin blood flow, which is under different autonomic control than heart rate. |
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Authors:
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Toshimitsu Takahashi; Yoriko Takikawa; Reiko Kawagoe; Satoshi Shibuya; Takayuki Iwano; Shigeru Kitazawa |
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Publication Detail:
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Type: JOURNAL ARTICLE Date: 2011-5-10 |
Journal Detail:
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Title: NeuroImage Volume: - ISSN: 1095-9572 ISO Abbreviation: - Publication Date: 2011 May |
Date Detail:
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Created Date: 2011-5-23 Completed Date: - Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 9215515 Medline TA: Neuroimage Country: - |
Other Details:
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Languages: ENG Pagination: - Citation Subset: - |
Copyright Information:
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Copyright © 2011 Elsevier Inc. All rights reserved. |
Affiliation:
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Department of Neurophysiology, Juntendo University Graduate School of Medicine, Tokyo, Japan; CREST, Japan Science and Technology Corporation, Tokyo, Japan; Neuroscience Research Institute, National Institute of Advanced Industrial Science and Technology, Japan. |
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From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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