Genetic Targeting of Specific Populations of Spinal Interneurons

Interneuron-specific enhancer elements for genes expressed in known types of dorsal interneurons were identified by Prof. Klar's group in our department (see collaborations). These enhancer elements are cloned upstream of Cre recombinase, injected to the neural tube of the developing (E3) chick embryo with a conditional GFP or GCaMP3 plasmids, and electroporated in ovo into specific populations of dorsal interneurons. Ten to 12 days later (E13-15), the spinal cord is isolated and the segmental and spatial distribution, axonal trajectories, and connectomes of the genetically identified interneurons are determined. The activity patterns of known sub-types of interneurons targeted with the genetically encoded calcium sensor GCaMP3 are imaged and the correlation between the optical and the concurrently recorded motor output is examined (Etlin et al. 2011, Hadas et al. 2011).