Synchronous multiscale neuroimaging environment for critically sampled physiological analysis of brain function:...

Area of Science:

• Neuroscience
• Physiological monitoring
• Brain imaging

Background:

• Resting-state functional connectivity is linked to very-low-frequency fluctuations (<0.1 Hz) in neuronal activity.
• Physiological oscillations like vasomotor waves and cardiorespiratory pulsations can affect indirect brain function measures, such as the BOLD signal in fMRI.
• Previous studies faced challenges in correlating physiological oscillations with spontaneous BOLD signals due to differing data sampling rates.

Purpose of the Study:

• To investigate the influence of physiological oscillations on spontaneous BOLD signals using ultrafast imaging.
• To introduce and validate the Hepta-scan multimodal concept for synchronous MREG and physiological monitoring.
• To explore the correlation between electrophysiological signals, hemodynamic changes, and brain network activity in the very-low-frequency range.

Main Methods:

• Development and application of the Hepta-scan multimodal concept, integrating magnetic resonance encephalography (MREG) with scalp electroencephalography (EEG), near-infrared spectroscopy (NIRS), and noninvasive blood pressure monitoring.
• Utilizing ultrafast MREG sequences for critical sampling of brain signals.
• Analyzing synchronous data streams to assess correlations in the very-low-frequency (VLF) range, particularly focusing on the default mode network (DMN).

Main Results:

• Preliminary results indicate that VLFFs in the BOLD signal are influenced by vasomotor and electrophysiological sources when cardiorespiratory signals are not aliased.
• High correlation coefficients were observed between MREG signals of the ventromedial default mode network (DMNvmpf) and electrophysiological signals in the VLF range.
• Oxyhemoglobin, deoxyhemoglobin, and vasomotor waves showed significant correlation with DMNvmpf activity. Shorter time windows revealed significantly higher correlation coefficients, indicating temporal non-stationarity.

Conclusions:

• The Hepta-scan approach enables the investigation of physiological influences on brain activity at critical sampling rates.
• VLFFs in BOLD signals are demonstrably affected by physiological oscillations, particularly in the VLF range.
• The temporal nonstationary nature of brain activity necessitates the use of appropriate time windows for accurate correlation analysis.