Neuronal or hemodynamic? Grappling with the functional MRI signal

Area of Science:

• Neuroimaging
• Biophysics

Background:

• Magnetic Resonance Imaging (MRI) and functional MRI (fMRI) are crucial for neuroscience.
• Continuous innovation is driven by interdisciplinary collaboration.

Purpose of the Study:

• To describe the field of fMRI through the lens of separating hemodynamic and neuronal information.
• To highlight how pulse sequences, activation paradigms, and processing methods yield novel insights.

Main Methods:

• Focus on the central problem of distinguishing hemodynamic responses from neuronal activity.
• Integration of pulse sequence design, experimental paradigm design, and data processing techniques.
• Utilizing advanced MRI techniques to extract detailed physiological and neural information.

Main Results:

• Extraction of diverse information including activation onset latency, metabolic rate, and neuronal adaptation.
• Assessment of vascular properties like patency and vessel diameter.
• Quantification of vigilance and subvoxel activation through various experimental measures.
• Analysis of time series latency, hemodynamic shape, MR phase, and multivoxel patterns.
• Investigation of R2*/R2 ratios, metabolic rate changes, and fluctuation dynamics.
• Examination of resting-state correlations and echo time dependence.

Conclusions:

• fMRI is a cornerstone for understanding the human brain, with ongoing advancements.
• Novel information extraction is achieved through the integration of various fMRI components.
• The described methods enable high-quality data acquisition for detailed brain analysis.