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Abstract:
The hippocampus plays critical roles in learning and memory, as well as pathological states such as epilepsy and Alzheimer’s disease. To better understand its neural network function, the multi-modality methodology has been implemented in both in vitro and in vivo conditions. However, the large-scale hippocampal vascular hemodynamic responses linked to specific neural activity remains to be elucidated at the single-vessel level through the hippocampus. We merged the fiber optic calcium recording with optogenetically driven single-vessel fMRI to obtain concurrent neuronal calcium signal with blood-oxygen-level-dependent and cerebral-blood-volume (CBV) signal from individual venules and arterioles, respectively, which are aligned in an interleaved pattern to circulate blood through the hippocampus. This multi-modal fMRI platform detects specific spatiotemporal hemodynamic patterns from hippocampal vasculature correlated with physiologically evoked and spreading depression-like calcium events. The calcium event-related single-vessel fMRI hemodynamic modeling reveals significantly reduced neurovascular coupling efficiency upon spreading depression-like events, providing a direct measure of the hippocampal vascular function at varied states in animal models.
