Intrinsic macroscale oscillatory modes driving long range functional connectivity detected with ultrafast fMRI

Abstract

The fundamental principles driving spontaneous long-range correlations between distant brain areas - known as intrinsic functional connectivity - remain unclear. To investigate this, we develop an ultrafast functional Magnetic Resonance Imaging (fMRI) approach with unprecedented temporal resolution (38 milliseconds) in the rat brain. We detect a repertoire of principal components exhibiting standing wave properties, i.e., with phase relationships varying gradually across space and oscillating in time, driving in- and anti-phase synchronization across distinct cortical and subcortical structures. The spatial configuration, stability and peak frequency of these standing waves is found to depend on the sedation/anaesthesia state, with medetomidine sedation revealing the most stable (i.e., less damped) standing waves, resonating at frequencies extending up to 0.25 Hz. Our findings show that the complex activity patterns observed in resting-state fMRI signals result from the superposition of standing waves, supporting the hypothesis that intrinsic functional connectivity is inherently associated to resonance phenomena.

Extensive topographic remapping and functional sharpening in the adult rat visual pathway upon first visual experience

“…The neural basis of the plastic mechanisms here reported, i.e., whether it is Hebbian plasticity (associated with positive feedback) or homeostatic plasticity (linked with negative feedback) can be further investigated using ultra-fast resting state MRI approached together with connectivity models, i.e., connective field [95] and [96].…”