Mapping cardiac and respiratory pulsations simultaneously with functional connectivity in the rat brain using zero...

Area of Science:

• Neuroimaging
• Physiology
• Biophysics

Background:

• Vascular pulsations are vital for brain perfusion and clearance, but their study in preclinical models is difficult.
• Altered pulsations are linked to aging and neurodegenerative diseases, highlighting the need for advanced imaging techniques.

Purpose of the Study:

• To assess the feasibility of zero echo time (ZTE) functional MRI (fMRI) for capturing cardiac and respiration pulsations in the rat brain.
• To evaluate ZTE fMRI's ability to detect physiological dynamics and neural connectivity simultaneously.

Main Methods:

• Utilized ZTE fMRI in rats under isoflurane anesthesia.
• Employed retrospective binning to analyze cardiac and respiration pulsations.
• Modulated cardiovascular state with medetomidine and performed functional connectivity analysis.

Main Results:

• ZTE fMRI achieved an 8ms temporal resolution, robustly detecting physiological pulsations across the rat brain, particularly in arteries.
• Cardiac pulsation amplitudes significantly increased under combined medetomidine-isoflurane anesthesia.
• Respiration-related pulsations remained stable, while functional connectivity decreased, demonstrating sensitivity to neural dynamics.

Conclusions:

• ZTE fMRI is a feasible technique for in vivo assessment of cerebrovascular pulsatility and functional connectivity in preclinical models.
• This method enables simultaneous evaluation of fast physiological dynamics and slower neural activity.
• ZTE fMRI provides a powerful tool for investigating brain dynamics in health and disease.