Abstract
The cerebellar system helps modulate and fine-tune motor action. Purkinje cells (PCs) provide the sole output of the cerebellar cortex, therefore, any cerebellar involvement in motor activity must be driven by changes in PC firing rates. Several different cell types influence PC activity including excitatory input from parallel fibers and inhibition from molecular layer interneurons (MLIs). Similar to PCs, MLI activity is driven by parallel fibers, therefore, MLIs provide feed-forward inhibition onto PCs. To aid in the experimental assessment of how molecular layer inhibition contributes to cerebellar function and motor behavior, we characterized a new knock-in mouse line with Cre recombinase expression under control of endogenous c-kit transcriptional machinery. Using these engineered c-Kit mice, we were able to obtain high levels of conditional MLI transduction in adult mice using Cre-dependent viral vectors without any PC or granule cell labeling. We then used the mouse line to target MLIs for activity perturbation in vitro using opto- and chemogenetics.
Highlights
Neural activity in the cerebellum contributes to the coordination of motor tasks and is required for adaptation of many learned movements [1,2,3,4]
On inspection of tissue infected with associated virus (AAV) using the hSyn promoter, it was apparent that interneurons in the inner portion of the molecular layer were preferentially labeled indicating biased transduction of presumptive basket cells by viruses containing this cis-element as evidenced by the welldefined axon plexus of pinceaux surrounding Purkinje cells (PCs) (Fig 2A)
The use of c-kitIRES-Cre mice enabled the expression of marker proteins as well as genetically encoded effectors in molecular layer interneurons (MLIs), independent of PCs and granule cells (GrCs), allowing for their activation or inactivation, demonstrating the flexibility of this mouse line and potential utility for ex vivo and in vivo circuit analysis experiments
Summary
Neural activity in the cerebellum contributes to the coordination of motor tasks and is required for adaptation of many learned movements [1,2,3,4]. Elucidation of cerebellar function during movement requires an understanding of how the various inputs onto PCs affect their excitability and spike output Most prominently, these include both excitatory climbing fiber projections from the inferior olive and parallel fiber axons of granule cells (GrCs) as well as two types of inhibitory molecular layer interneurons: stellate cells and basket cells (collectively referred to as MLIs). Experimental approaches to reveal the role of cell types in neural circuit function are greatly aided by targeting strategies often involving conditional mutagenesis using the Cre-loxP recombination system under cell-type control of a genetic marker [5]. For this reason, genetic targeting of MLIs is critical to advance circuit-level understanding of the cerebellum
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
