Functional mapping of whole mouse brain interneuronal circuitry
Description and scientific context:
Distant brain regions are believed to communicate through long--‐range, inhibitory interneuronal projections. The whole brain connectivity still remains to be established. In this experiment, mice where injected in the medial septum – a region thought to be involved in coordinating various brain regions --‐ with an adenovirus that expresses the green fluorescent protein, but also a channel rhodopsin to allow functional, optogenetic control of these projections. These mice also constitutively express the red fluorescent protein TdTomato in every interneuron (see how the cerebellum on the left--‐hand side is enriched!). Also, notice that one major projection site is the hippocampus that contains many green fluorescent fibers. This supports the idea that hippocampal synchrony could rely on medial septum activity, which we are now investigating in vivo using optogenetics.
Specimen and labels:
GFP--‐labelled projection fibers from the medial septum, tdTomato (red)--‐labelled interneurons , and DAPI (blue) counterstaining of cell nuclei from a fixed brain, sagittal slice of a mouse whole brain.
Olympus slide scanner, epifluorescent illumination, 10x dry objective