Abstract

Speaker: Samira M. Epp, Friedrich-Alexander University, Erlangen, Germany.

Title: BOLD signal changes can oppose oxygen metabolism across the human cortex

Abstract: Functional magnetic resonance imaging measures brain activity indirectly by monitoring changes in blood oxygenation levels, known as the blood-oxygenation-level-dependent (BOLD) signal, rather than directly measuring neuronal activity. This approach crucially relies on neurovascular coupling, the mechanism that links neuronal activity to changes in cerebral blood flow. However, it remains unclear whether this relationship is consistent for both positive and negative BOLD responses across the human cortex. In our recent paper (https://doi.org/10.1038/s41593-025-02132-9), we found that about 40% of voxels with significant BOLD signal changes during various tasks showed reversed oxygen metabolism, particularly in the default mode network. These ‘discordant’ voxels differed in baseline oxygen extraction fraction and regulated oxygen demand via oxygen extraction fraction changes, whereas ‘concordant’ voxels depended mainly on cerebral blood flow changes. I will talk about the main findings of our recent work and give a short outlook on current work.

• I am currently working as a PostDoc at the FAU (Friedrich-Alexander University) in Nürnberg-Erlangen (Neuroradiology), in the working group of Prof. Valentin Riedl (“Neuroimaging of immunological and metabolic processes”)
• I finished my PhD in ‘systemic neurosciences’ in 2023 in Munich, at the Graduate School of Systemic Neurosciences, a collaboration between LMU (Ludwig-Maximilians-University) and TUM (Technical University, Munich), also in the working group of Prof. Riedl (Neuroimaging Center, Neuroradiology)
• Graduated 2018 at the HU (Humboldt University) in Berlin, Masters in Psychology
• During my studies, I have been working as a research assistant for 4 years at the MPI (Max-Planck-Institute) for Human Development in Berlin, working mainly with fMRI BOLD data

Venue: MRC CBU West Wing Seminar Room and Zoom https://us02web.zoom.us/j/82385113580?pwd=RmxIUmphQW9Ud1JBby9nTDQzR0NRdz09 (Meeting ID: 823 8511 3580; Passcode: 299077)