Causally probing the neural rhythms that support functional connectivity

The relationship between BOLD signal correlations and neuronal correlations has largely been studied by modelling the associations between fMRI and electrophysiological recordings. These studies, while critical for understanding this relationship, are confounded by the interdependence between different electrophysiological rhythms. In this presentation I will show recent work where we used optogenetic stimulation of the mouse DMN to causally investigate how nested rhythms impact large scale functional connectivity. This rhythmic stimulation is functionally distinct from canonical block design stimulation, resulting in propagation of the rhythm throughout the DMN with region specific phase differences that are envelope, but not carrier, frequency dependent. I will provide evidence for a neural origin of these phase differences and discuss how traditional functional connectivity calculations are affected by them. I will also provide evidence for resonant properties within the stimulated axonal network. These results shed light on the relationship between haemodynamic and electrophysiological correlations, and how distributed networks like the DMN respond to targeted neuromodulation.