Speaker

Ben Bristow

Topic

Ben will discuss a recent paper (BOLD signal changes can oppose oxygen metabolism across the human cortex) that revisits one of the central assumptions underlying functional MRI. Although the blood-oxygen-level-dependent (BOLD) signal forms the foundation of most fMRI research, it is not a direct measure of neural activity. Instead, BOLD reflects a complex interaction between cerebral blood flow, blood oxygenation, and oxygen metabolism. The study examines whether changes in the BOLD signal provide a consistent proxy for changes in neural activity across the human cortex. Using quantitative MRI measures of cerebral oxygen metabolism, the authors report that a substantial proportion of brain regions showed metabolic changes that diverged from what would be predicted by the direction of the BOLD response, suggesting that the relationship between neural activity and BOLD may be more variable than commonly assumed. These findings have important implications for the interpretation of fMRI studies, particularly in situations where vascular or metabolic physiology may itself be changing.

About the Speaker

Ben Bristow is a PhD candidate at Mātai Medical Research Institute and the University of Auckland. His research uses functional MRI to investigate longitudinal changes in brain connectivity during methamphetamine abstinence, with the aim of improving our understanding of recovery and relapse processes.