Impacts of Caffeine Consumption on Brain and CSF Dynamics: An EEG-fMRI Study
Poster No:
2404
Submission Type:
Abstract Submission
Authors:
Lina Alqam1, Kadir Yildirim1, Kübra Eren1, Belal Tavashi1, Elif Can1, Cem Karakuzu1, Alp Dincer2, Pinar S Ozbay1
Institutions:
1Bogazici University, Istanbul, Turkey, 2Acibadem University, Istanbul, Turkey
First Author:
Co-Author(s):
Introduction:
This study seeks to explore the relations between caffeine intake, brain activity, cerebrospinal fluid (CSF) flow during rest and alert conditions. We analyzed the correlations among specific brain regions, CSF flow patterns and EEG power in individuals post-caffeine consumption, emphasizing caffeine's impact on these neural and autonomic processes. Through these objectives, we aim to enhance our understanding of the complex relationship between caffeine, brain function, and physiological dynamics.
Methods:
Resting state fMRI data were obtained at 3 T scanner with GRE-EPI (FA = 90, TR = 3 s, TE = 36 ms, in-place resolution = 2.5mm, number of TRs = 135). Cognitive task was elicited by an arithmetic task requiring solving an equation with one unknown. Problems were displayed against a gray background with a fixation dot. The experiment consisted of three blocks; each block began with a 45-second period of initial rest. This was followed by a 9-second mental arithmetic task, where a two-digit equation appeared. Afterward, there was a 36-second period of rest and focus on a fixation point, followed by a different mental task and another period of rest. EEG data was collected simultaneously with 32 channel head coil (Brain Products). 5 subjects were included in the analyses, 3 of which underwent simultaneous EEG-fMRI acquisition. Repeated scans were performed following immediate intake of caffeine pills, first scan 10 minutes second scan 30 minutes following intake. The subjects were not informed if the pill was caffeine or placebo. Preprocessing of fMRI data followed the suggested 'afni_proc' pipeline (AFNI (1)), including removal of signal drifts, slice-timing correction, realignment of consecutive volumes, registration to MNI template, smoothing (3 mm FWHM), and regression of motion parameters. Brain Products Analyzer's template approach was used to eliminate the MRI gradient and cardioballistic artifacts in the contaminated EEG data. This method required using average artifact subtraction (AAS) (3). The EEG data was subjected to a band-pass filter with a frequency range of 0.5-35 Hz after applying ICA, and Fz was used as a reference channel. To investigate lag dependent correlations, we used various regions of interest and calculated cross-correlations 1) among themselves, 2) with CSF signal (4th ventricle), and 3) EEG alpha and beta power. We also performed connectivity analysis based on positive and negative peaks in cross-correlations.
Results:
After caffeine intake, our study observed an increase in positive lag correlation between the 4th ventricle and the DMN regions, indicating a delay in CSF signal. We noted a general increase in positive peaks for correlations between resting state scans. Persistent negative correlation between CSF and ROIs, potentially linked to drowsiness. Arithmetic task shows an increased positive lag correlation at 0 lag between IPS and ACC, which are known for visual attention and awareness, suggesting a synchronization between these mechanisms. An increased correlation (Fig. 1) at 0 lag between CSF and EEG alpha and low beta powers, which may be related to increased CSF flow due to sympathetic activity after caffeine. EEG rest analysis indicated a reduced alpha power after caffeine intake while task analysis showed a rise in beta power following the caffeine specifically in the occipital and parietal electrodes. Subjects showed a decreased alpha band brainwave activity, signifying heightened alertness during the second resting session. Beta band, on the contrary, was enhanced by caffeine during the second arithmetic exercise suggesting higher level of cognitive processing (Fig. 2).
·Fig. 1: Left: Resting state, Right: Arith task, (top row) Correlations between various ROIs (N=5), (middle row) Correlations between CSF and EEG powers (N=3), (bottom row) Connectivity matrices
·Fig. 2: (Left): EEG electrodes, (top right), (bottom left): Normalized alpha and beta powers across two different sessions, (bottom right): power difference in dB in both alpha and beta bands.
Conclusions:
Our results suggest that caffeine influences the behavior of alpha and beta power difference in both mental arithmetic task and rest sessions. An increased connectivity for positive lag in regions of interest is also shown for both of these sessions, while the negative lag showed a decrease in only resting state scans.
Modeling and Analysis Methods:
Activation (eg. BOLD task-fMRI)
Novel Imaging Acquisition Methods:
BOLD fMRI
EEG
Multi-Modal Imaging 1
Physiology, Metabolism and Neurotransmission :
Neurophysiology of Imaging Signals 2
Keywords:
Electroencephaolography (EEG)
fMRI CONTRAST MECHANISMS
FUNCTIONAL MRI
1|2Indicates the priority used for review
Provide references using author date format
2. Birn RM et al. Neuroimage, 2006
3. Allen, P. J. et al., NeuroImage 2000
4. Ozbay P et al., Neuroimage, 2019
4. Picchioni D et al., Neuroimage, 2020