Department or Program
Primary Wellesley Thesis Advisor
Michael C. Wiest
Alan P. Jasanoff
Sarah J. Bricault
Resting state functional connectivity (RSFC) is a phenomenon where blood oxygen-level dependent (BOLD) signal correlation is observed between brain regions when an animal is at rest. As an occurrence observed and conserved across species, variations and abnormalities in RSFC can indicate underlying neurological diseases and thus provide diagnostic potential. However, despite its importance, not much is known about the drivers of RSFC. Here we examine the drivers of RSFC in the rat brain with respect to the well-defined primary somatosensory cortex and provide support for the hypothesis that thalamic input contributes to primary somatosensory cortex (S1) RSFC. Using fluorescent muscimol, we inactivated the brain region that provides the most afferent input into the S1, the ventrobasal complex (VB) of the thalamus. We then utilized an awake-paralyzed method previously developed by the lab to image the change in RSFC through functional magnetic resonance imaging (fMRI). We observed a decrease in cross-correlation between various S1 subregions, both within and across hemispheres, following VB inactivation. In particular, we observed a near-complete reduction of bilateral correlations in the barrel cortex. In addition, we observed significant decrease in spectral density in S1 subregions that have large topographical representations in the thalamus. These results suggest that S1 RSFC arises, at least in part, due to external input either originating from, or passing through the VB.
Available for download on Wednesday, April 20, 2022