The dynamic relationship between cerebral blood flow and venous cerebral blood volume under different types of stimuli

Motivation: The original calibrated BOLD model measures oxygen metabolism using a steady-state relationship between cerebral blood flow (CBF) and cerebral blood volume (CBV), neglecting temporal dynamics. To capture these dynamics, a more robust biophysical model is required. Goal(s): This study seeks to improve our understanding of CBF-CBV dynamics while using a Windkessel model across different stimuli. Approach: We developed a Windkessel model with vascular flow as resistive and capacitive components, validated it by comparing its transient dynamics with other models under various stimuli. Results: The Windkessel and transient balloon model mostly outperformed steady-state balloon model. Impact: The transient coupling of CBF and CBV is incompletely understood, limiting the interpretation of BOLD dynamics and quantitative measurements of brain physiology. We examined and modelled the transient behaviour of CBF and venous CBV during a range of tasks.