Whole mouse brain reconstruction and registration to a reference atlas with standard histochemical processing of coronal sections

Advances in molecular neuroanatomical tools have expanded the ability to map in detail connections of specific neuron subtypes in the context of behaviorally driven patterns of neuronal activity. Analysis of such data across the whole mouse brain, registered to a reference atlas, aids in understanding the functional organization of brain circuits related to behavior. A process is described to image mouse brain sections labeled with standard histochemical techniques, reconstruct those images into a whole brain image volume and register those images to the Allen Mouse Brain Common Coordinate Framework. Image analysis tools automate detection of cell bodies and quantification of axon density labeling in the structures in the annotated reference atlas. Examples of analysis are provided for mapping the axonal projections of layer‐specific cortical neurons using Cre‐dependent AAV vectors and for mapping inputs to such neurons using retrograde transsynaptic tracing with modified rabies viral vectors. Method is described for processing mouse brains with standard immunohistochemical techniques to reconstruct a whole brain rendering from coronal sections, which is aligned to the Allen Mouse Brain Common Coordinate Framework for quantitative analysis of labeled neurons and processes.