We took advantage of a variant of modified rabies virus that appears highly efficient at crossing synapses. We used this variant with Cre knockin mice or viral constructs that permitted genetic access to specific excitatory IL projection neurons to map the neurons targeting different classes of mouse infralimbic cortical neurons. For each neuron class, 3-5 mice were prepared and serial coronal slices were imaged by confocal microscopy. For analysis, a semi-automated alignment procedure was performed to assign neurons to individual brain regions.

For additional details see the citation below.

Hippocampal and thalamic afferents form distinct synaptic microcircuits in the mouse frontal cortex
Kourtney Graham², Nelson Spruston^1*, Erik B. Bloss^1,2*
bioRxiv 2021.03.12.435140; doi: https://doi.org/10.1101/2021.03.12.435140

¹Howard Hughes Medical Institute, Janelia Research Campus, Ashburn, VA 20147, USA

²The Jackson Laboratory, 600 Main Street, Bar Harbor, ME 04609, USA

^*Corresponding author