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Greater contribution of cerebral than extracerebral hemodynamics to near-infrared spectroscopy signals for functional activation and resting-state connectivity in infants.

Funane T, Homae F, Watanabe H, Kiguchi M, Taga G - Neurophotonics (2014)

Bottom Line: The deep-layer contribution was found to be large during resting [67% at S-D 20 mm, 78% at S-D 30 mm for oxygenated hemoglobin (oxy-Hb)] as well as during the speech condition (72% at S-D 20 mm, 82% at S-D 30 mm for oxy-Hb).A left-right connectivity analysis showed that correlation coefficients between left and right channels did not differ between original- and deep-layer signals under no-stimulus conditions and that of original- and deep-layer signals were larger than those of the shallow layer.These results suggest that NIRS signals obtained in infants with appropriate S-D distances largely reflected cerebral hemodynamic changes.

View Article: PubMed Central - PubMed

Affiliation: Hitachi, Ltd. , Central Research Laboratory, 2520 Akanuma, Hatoyama, Saitama 350-0395, Japan.

ABSTRACT
While near-infrared spectroscopy (NIRS) has been increasingly applied to neuroimaging and functional connectivity studies in infants, it has not been quantitatively examined as to what extent the deep tissue (such as cerebral tissue) as opposed to shallow tissue (such as scalp), contributes to NIRS signals measured in infants. A method for separating the effects of deep- and shallow-tissue layers was applied to data of nine sleeping three-month-old infants who had been exposed to 3-s speech sounds or silence (i.e., resting state) and whose hemodynamic changes over their bilateral temporal cortices had been measured by using an NIRS system with multiple source-detector (S-D) distances. The deep-layer contribution was found to be large during resting [67% at S-D 20 mm, 78% at S-D 30 mm for oxygenated hemoglobin (oxy-Hb)] as well as during the speech condition (72% at S-D 20 mm, 82% at S-D 30 mm for oxy-Hb). A left-right connectivity analysis showed that correlation coefficients between left and right channels did not differ between original- and deep-layer signals under no-stimulus conditions and that of original- and deep-layer signals were larger than those of the shallow layer. These results suggest that NIRS signals obtained in infants with appropriate S-D distances largely reflected cerebral hemodynamic changes.

No MeSH data available.


Related in: MedlinePlus

Arrangement of the light sources and detectors in near-infrared spectroscopy (NIRS) measurements for hemodynamic responses to auditory stimuli in infants. Filled and open circles show the positions of the light sources and detectors, respectively. The source optical fibers were placed on the T3 and T4 positions of the International 10/20 system. The position of the measurement channel for recording the changes in oxygenated and deoxygenated hemoglobin (oxy- and deoxy-Hb) signals is defined as the midpoint between the source and detector. Four different detectors placed in a line on each hemisphere detect reflected light from a single incident position. Thus, hemoglobin signals are simultaneously measured by a total of eight channels. The data obtained at source-detector 40-mm channel were not used in the analysis.
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f1: Arrangement of the light sources and detectors in near-infrared spectroscopy (NIRS) measurements for hemodynamic responses to auditory stimuli in infants. Filled and open circles show the positions of the light sources and detectors, respectively. The source optical fibers were placed on the T3 and T4 positions of the International 10/20 system. The position of the measurement channel for recording the changes in oxygenated and deoxygenated hemoglobin (oxy- and deoxy-Hb) signals is defined as the midpoint between the source and detector. Four different detectors placed in a line on each hemisphere detect reflected light from a single incident position. Thus, hemoglobin signals are simultaneously measured by a total of eight channels. The data obtained at source-detector 40-mm channel were not used in the analysis.

Mentions: An NIRS system (ETG-100, Hitachi Medical Corporation, Tokyo, Japan)6,7 was used to measure the hemodynamic responses of infants. The optical fibers for the source and detectors were placed over the temporal cortices on both hemispheres. On the left hemisphere, the source was set on the T3 position on the basis of the international 10–20 system of electrode placement,49 and four detectors were mounted in a line at 10, 20, 30, and 40 mm from the source. On the right hemisphere, the source and four detectors were placed on homologous positions. Figure 1 shows the arrangement of the source and detectors in NIRS measurements for hemodynamic responses to auditory stimuli in infants. Thus all the measurement channels in the present study were likely located on the temporal cortex.16,50 These regions have also been reported to respond to speech sounds while infants are quietly sleeping.51


Greater contribution of cerebral than extracerebral hemodynamics to near-infrared spectroscopy signals for functional activation and resting-state connectivity in infants.

Funane T, Homae F, Watanabe H, Kiguchi M, Taga G - Neurophotonics (2014)

Arrangement of the light sources and detectors in near-infrared spectroscopy (NIRS) measurements for hemodynamic responses to auditory stimuli in infants. Filled and open circles show the positions of the light sources and detectors, respectively. The source optical fibers were placed on the T3 and T4 positions of the International 10/20 system. The position of the measurement channel for recording the changes in oxygenated and deoxygenated hemoglobin (oxy- and deoxy-Hb) signals is defined as the midpoint between the source and detector. Four different detectors placed in a line on each hemisphere detect reflected light from a single incident position. Thus, hemoglobin signals are simultaneously measured by a total of eight channels. The data obtained at source-detector 40-mm channel were not used in the analysis.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4478757&req=5

f1: Arrangement of the light sources and detectors in near-infrared spectroscopy (NIRS) measurements for hemodynamic responses to auditory stimuli in infants. Filled and open circles show the positions of the light sources and detectors, respectively. The source optical fibers were placed on the T3 and T4 positions of the International 10/20 system. The position of the measurement channel for recording the changes in oxygenated and deoxygenated hemoglobin (oxy- and deoxy-Hb) signals is defined as the midpoint between the source and detector. Four different detectors placed in a line on each hemisphere detect reflected light from a single incident position. Thus, hemoglobin signals are simultaneously measured by a total of eight channels. The data obtained at source-detector 40-mm channel were not used in the analysis.
Mentions: An NIRS system (ETG-100, Hitachi Medical Corporation, Tokyo, Japan)6,7 was used to measure the hemodynamic responses of infants. The optical fibers for the source and detectors were placed over the temporal cortices on both hemispheres. On the left hemisphere, the source was set on the T3 position on the basis of the international 10–20 system of electrode placement,49 and four detectors were mounted in a line at 10, 20, 30, and 40 mm from the source. On the right hemisphere, the source and four detectors were placed on homologous positions. Figure 1 shows the arrangement of the source and detectors in NIRS measurements for hemodynamic responses to auditory stimuli in infants. Thus all the measurement channels in the present study were likely located on the temporal cortex.16,50 These regions have also been reported to respond to speech sounds while infants are quietly sleeping.51

Bottom Line: The deep-layer contribution was found to be large during resting [67% at S-D 20 mm, 78% at S-D 30 mm for oxygenated hemoglobin (oxy-Hb)] as well as during the speech condition (72% at S-D 20 mm, 82% at S-D 30 mm for oxy-Hb).A left-right connectivity analysis showed that correlation coefficients between left and right channels did not differ between original- and deep-layer signals under no-stimulus conditions and that of original- and deep-layer signals were larger than those of the shallow layer.These results suggest that NIRS signals obtained in infants with appropriate S-D distances largely reflected cerebral hemodynamic changes.

View Article: PubMed Central - PubMed

Affiliation: Hitachi, Ltd. , Central Research Laboratory, 2520 Akanuma, Hatoyama, Saitama 350-0395, Japan.

ABSTRACT
While near-infrared spectroscopy (NIRS) has been increasingly applied to neuroimaging and functional connectivity studies in infants, it has not been quantitatively examined as to what extent the deep tissue (such as cerebral tissue) as opposed to shallow tissue (such as scalp), contributes to NIRS signals measured in infants. A method for separating the effects of deep- and shallow-tissue layers was applied to data of nine sleeping three-month-old infants who had been exposed to 3-s speech sounds or silence (i.e., resting state) and whose hemodynamic changes over their bilateral temporal cortices had been measured by using an NIRS system with multiple source-detector (S-D) distances. The deep-layer contribution was found to be large during resting [67% at S-D 20 mm, 78% at S-D 30 mm for oxygenated hemoglobin (oxy-Hb)] as well as during the speech condition (72% at S-D 20 mm, 82% at S-D 30 mm for oxy-Hb). A left-right connectivity analysis showed that correlation coefficients between left and right channels did not differ between original- and deep-layer signals under no-stimulus conditions and that of original- and deep-layer signals were larger than those of the shallow layer. These results suggest that NIRS signals obtained in infants with appropriate S-D distances largely reflected cerebral hemodynamic changes.

No MeSH data available.


Related in: MedlinePlus