First order synaptic afferents to nucleus accumbens somatostatin interneurons.

A) Experimental design for cell type-specific retrograde trans-synaptic tracing using PRV-Introvert-GFP in SST-Cre mice. The tracing data shown are from three mice, but we have replicated the tracing in three separate experiments with consistent findings obtained. B) Trans-synaptic tracing of afferents to NAc somatostatin interneurons. GFP is shown in Green. PFC–prefrontal cortex (IL+PL), AON/OLF–anterior olfactory nucleus, PIR–piriform cortex, AI/GU–anterior insular/gustatory cortex, BLA–basolateral amygdala, AMY–amygdala (non-BLA), ENTl–entorhinal cortex, HYP–hypothalamus, PVT–periventricular nucleus of the thalamus, RE–reuniens nucleus, SUB–ventral subiculum, VTA–ventral tegmental area, NAc–nucleus accumbens. TH–tyrosine hydroxylase (Red). Scale bar = 100 μm. C) Synaptic connectivity of NAc somatostatin interneurons. Baseline connectivity of mouse NAc was adapted from the Allen Brain Atlas (http://connectivity.brain-map.org/). Baseline connectivity strength for overall NAc was set at a maximum of 3.5 and used as a cutoff for counting a region as part of the global NAc connectome. The width of the line connecting each node/region to the NAc corresponds to the reported baseline connectivity strength for overall NAc. We observed GFP+ cells in green nodes shown in (C), while we did not detect GFP in regions shown in black nodes. The size of the green node represents the number of GFP+ cells that were labeled in each region after tracing in SST-Cre mice. For every region shown, the width of the line connecting the node to the NAc represents the reported/expected strength of each connection. (D) Quantification of results shown in network diagram.