OHBM 2023 | 2793 | Symposium | Joana Cabral | Macroscale oscillatory wave patterns revealed with u…

Title: Macroscale oscillatory wave patterns revealed with ultrafast fMRI.
Session: Symposia
Speaker: Joana Cabral
Abstract: Spontaneous fluctuations in functional Magnetic Resonance Imaging (fMRI) signals correlate across distant brain areas, shaping functionally relevant intrinsic networks. However, the generative mechanism of fMRI signal correlations - and in particular their link with locally-detected ultra-slow oscillations - remains unclear. To investigate this link, we recorded ultrafast ultrahigh field fMRI signals (9.4 Tesla, TR = 38 milliseconds) from rat brains across three anesthesia conditions. Principal component analysis revealed a repertoire of spatial wave patterns with fixed phase relationships across distinct cortical and subcortical structures, oscillating at frequencies extending up to 0.3 Hz depending on the anesthesia condition. Oscillatory modes are found to resonate at faster frequencies under medetomidine sedation and to reduce both in number, frequency, and duration with the addition of isoflurane. Peaking in power within clear anatomical boundaries, these oscillatory modes point to an emergent systemic property associated with resonance phenomena, questioning current assumptions regarding the local origin of oscillations detected in fMRI and providing novel insights into the organizing principles underpinning spontaneous long-range functional connectivity.