November 23, 2020

Wide-Field Calcium Imaging of Dynamic Cortical Networks During Locomotion

Behavior results in widespread activation of the cerebral cortex. To fully understanding the cerebral cortexs role in behavior therefore requires a mesoscopic level description of the cortical regions engaged and their functional interactions. Mesoscopic imaging of Ca2+ fluorescence through transparent polymer skulls implanted on transgenic Thy1-GCaMP6f mice reveals widespread activation of the cerebral cortex during locomotion, including not just primary motor and somatosensory regions but also premotor, auditory, retrosplenial, and visual cortices. To understand these patterns of activation, we used spatial Independent Component Analysis (sICA) that segmented the dorsal cortex of individual mice into 20-22 Independent Components (ICs). The resulting ICs are highly consistent across imaging sessions and animals. Using the time series of Ca2+ fluorescence in each IC, we examined the changes in functional connectivity from rest to locomotion. Compared to rest, functional connectivity increases prior to and at the onset of locomotion. During continued walking, a global decrease in functional connectivity develops compared to rest that uncovers a distinct, sparser network in which ICs in secondary motor areas increase their correlations with more posterior ICs in somatosensory, motor, visual, and retrosplenial cortices. Eigenvector centrality analysis demonstrates that ICs located in premotor areas increase their influence on the network during locomotion while ICs in other regions, including somatosensory and primary motor, decrease in importance. We observed sequential changes in functional connectivity across transitions between rest and locomotion, with premotor areas playing an important role in coordination of computations across cortical brain regions.

 bioRxiv Subject Collection: Neuroscience

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