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  Changes in cytochrome-oxidase oxidation in the occipital cortex during visual stimulation: Improvement in sensitivity by the determination of the wavelength dependence of the differential pathlength

Kohl-Bareis, M., Nolte, C., Heekeren, H., Horst, S., Scholz, J., Obrig, H., et al. (1998). Changes in cytochrome-oxidase oxidation in the occipital cortex during visual stimulation: Improvement in sensitivity by the determination of the wavelength dependence of the differential pathlength. In D. A. Benaron, B. Chance, & M. Ferrari (Eds.), Proceedings of SPIE: Photon Propagation in Tissues III (pp. 18-27). Bellingham, Wash: SPIE.

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Item Permalink: https://hdl.handle.net/21.11116/0000-0003-2769-C Version Permalink: https://hdl.handle.net/21.11116/0000-0004-BA68-6
Genre: Conference Paper

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 Creators:
Kohl-Bareis, Matthias1, Author
Nolte, Christian1, Author
Heekeren, Hauke1, Author           
Horst, Susanne1, Author
Scholz, J.1, Author
Obrig, Hellmuth1, Author           
Villringer, Arno1, Author           
Affiliations:
1External Organizations, ou_persistent22              

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 Abstract: In this study we assess changes in the hemoglobin oxygenation (oxy-Hb, deoxy-Hb) and the Cytochrome-C-Oxidase redox state (Cyt-ox) in the occipital cortex during visual stimulation by near infrared spectroscopy. For the calculation of changes in oxy-Hb, deoxy-Hb and Cyt-ox from attenuation data via a modified Beer-Lambert equation, the wavelength dependence of the differential pathlength factor (DPF), i.e. the ratio of the mean optical pathlength and the physical light-source-detector separation, has to be taken into account. The wavelength dependence of the DPF determines the crosstalk between the different concentrations and is therefore essential for a high sensitivity. Here a simple method is suggested to estimate the wavelength dependence of the DPF((lambda) ) from pulse induced attenuation changes measured on the head of adult humans. The essence is that the DPF is the ratio of the attenuation changes over absorption coefficient changes and the spectral form of the pulse correlated absorption coefficient change is proportional to the extinction coefficient of blood. Indicators for the validity of the DPF((lambda) ) derived for wavelengths between 700 and 970 nm are the stability of the calculated oxy-Hb, deoxy-Hb and Cyt-ox signals with variations of the wavelength range included for their calculation and its overall agreement with the data available from the literature. The DPF derived from pulse measurements was used for the analysis of attenuation data from cortical stimulations. We show that Cyt-ox in the occipital cortex of human subjects is transiently oxidized during visual stimulation.
© (1998) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

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Language(s): eng - English
 Dates: 1998-01-01
 Publication Status: Issued
 Pages: -
 Publishing info: -
 Table of Contents: -
 Rev. Type: -
 Identifiers: DOI: 10.1117/12.301055
 Degree: -

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Title: BiOS Europe '97
Place of Event: San Remo, Italy
Start-/End Date: 1997-09-04 - 1997-09-08

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Title: Proceedings of SPIE: Photon Propagation in Tissues III
Source Genre: Proceedings
 Creator(s):
Benaron, David A.1, Editor
Chance, Britton1, Editor
Ferrari, Marco1, Editor
Affiliations:
1 External Organizations, ou_persistent22            
Publ. Info: Bellingham, Wash : SPIE
Pages: - Volume / Issue: 3194 Sequence Number: - Start / End Page: 18 - 27 Identifier: ISBN: 0-8194-2626-1