Neural activity underpins dynamic BOLD signals: findings from simultaneous wide-field fluorescent calcium imaging and fMRI.

Motivation: BOLD-fMRI measures whole-brain activity but lacks specificity, and suffers from low SNR, making it challenging to capture reliable dynamic activity patterns. Goal(s): We aim to further validate the detection of quasi-periodic patterns (QPPs), as measured by BOLD, using simultaneous wide-field fluorescent calcium imaging (WF-Ca²⁺) and fMRI. Approach: Mice with GCaMP-labelled excitatory neurons were imaged under isoflurane. QPP detection was accomplished using either cortical WF-Ca2+ or BOLD-fMRI data at the dataset- and subject-level. Results: Significant cross-modal agreement in QPP spatiotemporal structure was uncovered alongside some expected inter-subject variability. These finding help to affirm the neural origins of patterned cortical activity as detected by BOLD. Impact: Quasi-periodic patterns (QPPs), measured via BOLD-fMRI, are recurring low-frequency coordinated waves of brain activity that appear in humans and model species. Here, we extend the characterization of the neural underpinnings of QPPs using simultaneous wide-field fluorescent calcium imaging and BOLD-fMRI.