Thalamic low frequency activity contributes to resting-state cortical interhemispheric MRI functional connectivity

The brain consists of numerous interconnected parallel and hierarchical networks subserving sensory, behavioral and cognitive functions. Resting-state functional MRI (rsfMRI) connectivity has helped study the complex brain-wide functional networks. Yet, less is known about the role of thalamus in rsfMRI connectivity. Utilizing optogenetic excitation and pharmacological inactivation to manipulate the neural activity of somatosensory thalamocortical neurons, we demonstrate that thalamus contributes to rsfMRI connectivity within and beyond its sensory modality, likely through the recruitment of interhemispheric low frequency neural oscillations at all cortical layers. Our work highlights the thalamus as a pivotal structure underpinning rsfMRI connectivity observations.