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Caffeine differentially alters cortical hemodynamic activity during working memory: a near infrared spectroscopy study.

Heilbronner U, Hinrichs H, Heinze HJ, Zaehle T - BMC Res Notes (2015)

Bottom Line: In line with previous results, we did not detect an effect of caffeine on most aspects of behavior.Effects of caffeine on brain vasculature were detected as general reduction of HbO.Neuronal effects of caffeine are reflected in an increased concentration of HbR in the left hemisphere when performing a verbal memory task and suggest influences on metabolism.

View Article: PubMed Central - PubMed

Affiliation: DZNE, German Center for Neurodegenerative Diseases, Otto-von-Guericke University, Magdeburg, Germany. urs.heilbronner@med.uni-muenchen.de.

ABSTRACT

Background: Caffeine is a widely used stimulant with potentially beneficial effects on cognition as well as vasoconstrictive properties. In functional magnetic imaging research, caffeine has gained attention as a potential enhancer of the blood oxygenation level-dependent (BOLD) response. In order to clarify changes of oxy- and deoxyhemoglobin (HbO and HbR) induced by caffeine during a cognitive task, we investigated a working memory (WM) paradigm (visual 2-back) using near-infrared spectroscopy (NIRS).

Results: Behaviorally, caffeine had no effect on the WM performance but influenced reaction times in the 0-back condition. NIRS data demonstrate caffeine-dependent alterations of the course of the hemodynamic response. The intake of 200 mg caffeine caused a significant decrease of the HbO response between 20 and 40 s after the onset of a 2-back task in the bilateral inferior frontal cortex (IFC). In parallel, the HbR response of the left IFC was significantly increased due to caffeine intake.

Conclusions: In line with previous results, we did not detect an effect of caffeine on most aspects of behavior. Effects of caffeine on brain vasculature were detected as general reduction of HbO. Neuronal effects of caffeine are reflected in an increased concentration of HbR in the left hemisphere when performing a verbal memory task and suggest influences on metabolism.

No MeSH data available.


Effects of caffeine on left hemisphere cortical hemodynamics. The inset shows mean channel positions (averaged over subjects), visualized on the Montreal Neurological Institute (MNI) template brain. Black colored positions indicate the channels that were averaged to form the ROI. The left/right line graphs show time courses of relative concentrations of HbO/HbR in different experimental conditions. Vertical bars indicate the boundaries of time windows 1 and 2 (tw1 and tw2, respectively). The stimulation duration is indicated in the lower part of the graphs. The bar graphs above and below the line graphs depict mean individual maximum/minimum responses during the different time windows (see labels). The bar graphs depict mean HbO of the individual maximum response in tw1 (upper left graph), mean HbO of the individual minimum response in tw2 (lower left graph), mean HbR of the individual minimum response in tw1 (lower right graph), and mean HbR of the individual maximum response in tw2 (upper right graph)
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Fig1: Effects of caffeine on left hemisphere cortical hemodynamics. The inset shows mean channel positions (averaged over subjects), visualized on the Montreal Neurological Institute (MNI) template brain. Black colored positions indicate the channels that were averaged to form the ROI. The left/right line graphs show time courses of relative concentrations of HbO/HbR in different experimental conditions. Vertical bars indicate the boundaries of time windows 1 and 2 (tw1 and tw2, respectively). The stimulation duration is indicated in the lower part of the graphs. The bar graphs above and below the line graphs depict mean individual maximum/minimum responses during the different time windows (see labels). The bar graphs depict mean HbO of the individual maximum response in tw1 (upper left graph), mean HbO of the individual minimum response in tw2 (lower left graph), mean HbR of the individual minimum response in tw1 (lower right graph), and mean HbR of the individual maximum response in tw2 (upper right graph)

Mentions: We recorded the concentration of HbO and HbR at a sampling rate of 10 Hz using Hitachi’s ETG-4000 Optical Topography System (Hitachi Medical Systems, Germany) which uses a modified Beer-Lambert law to calculate hemoglobin concentrations. Thirty-three optodes were placed on the subject’s forehead from which 52 channels were recorded. Positioning of the optode grid was performed such that the middle optode of the most inferior row on the 3 × 11 optode grid was located on the point Fpz of the international 10/20 EEG system. The distances between the optode grid and both preauricular points were kept equivalent. One drawback with this approach is, as distances between individual optodes remain constant, the scalp area under which the content of HbO and HbR are assessed can be quite variable and thus complicate interpretation of results. To ameliorate this problem, we used the ETG-4000’s built-in 3D digitizer and obtained real-world coordinates of each optode position for each individual subject [29]. Subsequently, we transformed these coordinates to the Montral Neurological Institute (MNI) framework using the toolbox of NFRI functions [30] included in the software suite NIRS-SPM [31] to be able to provide the mean channel position on the MNI brain (see insets of Figs. 1, 2). The ETG-4000 software was used for averaging hemoglobin responses to single task blocks for each subject. Data were subsequently analyzed by the R software (see below).Fig. 1


Caffeine differentially alters cortical hemodynamic activity during working memory: a near infrared spectroscopy study.

Heilbronner U, Hinrichs H, Heinze HJ, Zaehle T - BMC Res Notes (2015)

Effects of caffeine on left hemisphere cortical hemodynamics. The inset shows mean channel positions (averaged over subjects), visualized on the Montreal Neurological Institute (MNI) template brain. Black colored positions indicate the channels that were averaged to form the ROI. The left/right line graphs show time courses of relative concentrations of HbO/HbR in different experimental conditions. Vertical bars indicate the boundaries of time windows 1 and 2 (tw1 and tw2, respectively). The stimulation duration is indicated in the lower part of the graphs. The bar graphs above and below the line graphs depict mean individual maximum/minimum responses during the different time windows (see labels). The bar graphs depict mean HbO of the individual maximum response in tw1 (upper left graph), mean HbO of the individual minimum response in tw2 (lower left graph), mean HbR of the individual minimum response in tw1 (lower right graph), and mean HbR of the individual maximum response in tw2 (upper right graph)
© Copyright Policy - OpenAccess
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC4590696&req=5

Fig1: Effects of caffeine on left hemisphere cortical hemodynamics. The inset shows mean channel positions (averaged over subjects), visualized on the Montreal Neurological Institute (MNI) template brain. Black colored positions indicate the channels that were averaged to form the ROI. The left/right line graphs show time courses of relative concentrations of HbO/HbR in different experimental conditions. Vertical bars indicate the boundaries of time windows 1 and 2 (tw1 and tw2, respectively). The stimulation duration is indicated in the lower part of the graphs. The bar graphs above and below the line graphs depict mean individual maximum/minimum responses during the different time windows (see labels). The bar graphs depict mean HbO of the individual maximum response in tw1 (upper left graph), mean HbO of the individual minimum response in tw2 (lower left graph), mean HbR of the individual minimum response in tw1 (lower right graph), and mean HbR of the individual maximum response in tw2 (upper right graph)
Mentions: We recorded the concentration of HbO and HbR at a sampling rate of 10 Hz using Hitachi’s ETG-4000 Optical Topography System (Hitachi Medical Systems, Germany) which uses a modified Beer-Lambert law to calculate hemoglobin concentrations. Thirty-three optodes were placed on the subject’s forehead from which 52 channels were recorded. Positioning of the optode grid was performed such that the middle optode of the most inferior row on the 3 × 11 optode grid was located on the point Fpz of the international 10/20 EEG system. The distances between the optode grid and both preauricular points were kept equivalent. One drawback with this approach is, as distances between individual optodes remain constant, the scalp area under which the content of HbO and HbR are assessed can be quite variable and thus complicate interpretation of results. To ameliorate this problem, we used the ETG-4000’s built-in 3D digitizer and obtained real-world coordinates of each optode position for each individual subject [29]. Subsequently, we transformed these coordinates to the Montral Neurological Institute (MNI) framework using the toolbox of NFRI functions [30] included in the software suite NIRS-SPM [31] to be able to provide the mean channel position on the MNI brain (see insets of Figs. 1, 2). The ETG-4000 software was used for averaging hemoglobin responses to single task blocks for each subject. Data were subsequently analyzed by the R software (see below).Fig. 1

Bottom Line: In line with previous results, we did not detect an effect of caffeine on most aspects of behavior.Effects of caffeine on brain vasculature were detected as general reduction of HbO.Neuronal effects of caffeine are reflected in an increased concentration of HbR in the left hemisphere when performing a verbal memory task and suggest influences on metabolism.

View Article: PubMed Central - PubMed

Affiliation: DZNE, German Center for Neurodegenerative Diseases, Otto-von-Guericke University, Magdeburg, Germany. urs.heilbronner@med.uni-muenchen.de.

ABSTRACT

Background: Caffeine is a widely used stimulant with potentially beneficial effects on cognition as well as vasoconstrictive properties. In functional magnetic imaging research, caffeine has gained attention as a potential enhancer of the blood oxygenation level-dependent (BOLD) response. In order to clarify changes of oxy- and deoxyhemoglobin (HbO and HbR) induced by caffeine during a cognitive task, we investigated a working memory (WM) paradigm (visual 2-back) using near-infrared spectroscopy (NIRS).

Results: Behaviorally, caffeine had no effect on the WM performance but influenced reaction times in the 0-back condition. NIRS data demonstrate caffeine-dependent alterations of the course of the hemodynamic response. The intake of 200 mg caffeine caused a significant decrease of the HbO response between 20 and 40 s after the onset of a 2-back task in the bilateral inferior frontal cortex (IFC). In parallel, the HbR response of the left IFC was significantly increased due to caffeine intake.

Conclusions: In line with previous results, we did not detect an effect of caffeine on most aspects of behavior. Effects of caffeine on brain vasculature were detected as general reduction of HbO. Neuronal effects of caffeine are reflected in an increased concentration of HbR in the left hemisphere when performing a verbal memory task and suggest influences on metabolism.

No MeSH data available.