Distinct Effects of Respiratory Depth and Frequency on CSF Flow

Motivation: The flow of cerebrospinal fluid (CSF) is essential for maintenance of brain function. Goal(s): We aimed to understand the effects of respiration on CSF flow dynamics by quantitatively testing the change in CSF flow across varying paced breathing frequencies. Approach: Using flow-sensitive fMRI, phase contrast imaging, and physiological recordings, we measured changes in CSF flow and velocity during a visually guided paced breathing task. Results: We examined CSF flow across breath frequencies ranging from 0.1 Hz to 0.25 Hz, and found that slower frequencies of breathing increase CSF flow, independent of breath depth. Impact: Our results demonstrate that key features of human respiration, its timing and its depth, induce separate effects on CSF flow. Our identification of respiratory frequency as a modulator of CSF flow provides an accessible mechanism to modulate CSF flow.