Neurovascular & experimental confounds when probing neuronal activity with fast fMRI: exploring evasive DIANA & DW-fMRI.

Motivation: Exploring the cerebrum's functional organisation and processing is challenging. Functional Magnetic Resonance Imaging (fMRI) measures neuronal activity (NA) noninvasively, but relies on indirect signals related to cerebral haemodynamics. Goal(s): We rigorously investigate if NA in the human brain can be measured using diffusion-weighted fMRI and Direct Imaging of Neuronal Activity (DIANA). Approach: We utilise DW-fMRI and DIANA at 3 Tesla to record the responses in the somatosensory cortex following electric stimulation of the digits. Results: We confirm BOLD responses in somatosensory cortex. Both DW-fMRI and DIANA also show stimulus-locked responses. However, we express concerns regarding electrical stimulation noise artefacts and neuronal inhibition. Impact: This study advances our understanding of neuronal activity measurement using innovative fMRI techniques. It sheds light on the challenges, potential artefacts, and optimal strategies for precise human brain mapping, which is crucial for both basic research and clinical applications.