Caffeine-Induced Global Reductions in Resting-State BOLD Connectivity Reflect Widespread Decreases in MEG Connectivity

Abstract

In resting-state functional magnetic resonance imaging (fMRI), the temporal correlation between spontaneous fluctuations of the blood oxygenation level dependent (BOLD) signal from different brain regions is used to assess functional connectivity. However, because the BOLD signal is an indirect measure of neuronal activity, its complex hemodynamic nature can complicate the interpretation of differences in connectivity that are observed across conditions or subjects. For example, prior studies have shown that caffeine leads to widespread reductions in BOLD connectivity but were not able to determine if neural or vascular factors were primarily responsible for the observed decrease. In this study, we used source-localized magnetoencephalography (MEG) in conjunction with fMRI to further examine the origins of the caffeine-induced changes in BOLD connectivity. We observed widespread and significant (p < 0.01) reductions in both MEG and fMRI connectivity measures, suggesting that decreases in the connectivity of resting-state neuro-electric power fluctuations were primarily responsible for the observed BOLD connectivity changes. The MEG connectivity decreases were most pronounced in the beta band. By demonstrating the similarity in MEG and fMRI based connectivity changes, these results provide evidence for the neural basis of resting-state fMRI networks and further support the potential of MEG as a tool to characterize resting-state connectivity.

Acute caffeine administration impact on working memory-related brain activation and functional connectivity in the elderly: A BOLD and perfusion MRI study

“…Subsequently, the WM-load related an increase in functional connectivity after caffeine intake observed here cannot be attributed to a nonspecific effect of this substance. Interestingly, a recent study combined fMRI and magnetoencephalography (MEG) to assess whether changes in resting state fMRI functional connectivity are due to vascular or neural factors (Tal et al, 2013). The functional connectivity changes in fMRI were paralleled by changes in MEG, which directly assesses neuro-electric activity.…”

Opportunities and methodological challenges in EEG and MEG resting state functional brain network research

“…Each state of vigilance has specific characteristics that contribute to differences in spectral power (Niedermeyer et al , 1987, Cantero et al , 1999 and functional connectivity (Kuhnert et al , 2010. Several factors have been identified that influence state of vigilance: circadian rhythm (Kuhnert et al , 2010), task performance before the recording , including neuropsychological testing, medication use, or even caffeine intake (Siepmann et al , 2002, Barry et al , 2011, Tal et al , 2013. Body posture and recording environment may also affect vigilance and, consequently, functional connectivity measures.…”

Applications of Resting State Functional MR Imaging to Neuropsychiatric Diseases

“…This type of research is still at an early stage with regard to robust replication, but preliminary indications are that there may be differences in response patterns following acute challenge between drugs as diverse as THC 130 , ketamine 131 , caffeine 132,133 , morphine and alcohol 134 and nicotine 135 . The latter drug increases connectivity within limbic circuits 136 .…”