Fig. 5. Physiological and structural neuroadaptations in RMTg-projecting dmPFC neurons following exposure to foot shock.

A For ex-vivo electrophysiology experiments, rats were injected with retrobeads into the RMTg. B Representative retrobead injection site in the RMTg. Scale bar = 1000 μm. C Significantly fewer spikes were observed in Shock-exposed rats relative to controls in current clamp recordings of retrobead-labeled dmPFC neurons. D Representative traces from a control and Shock-exposed rat. Decreased spiking was associated with a significant increase in E rheobase, H membrane capacitance, and I action potential height as well as a significant decrease in G membrane resistance and J action potential half-width. No significant difference was observed in F action potential threshold or K after hyperpolarization. L For structural analyses, an intersectional dual-virus approach was used to fill RMTg-projecting dmPFC neurons with yellow fluorescent protein (YFP). M Representative YFP-filled primary apical dendrites in the dmPFC and accompanying Imaris renderings for Context- and Shock-exposed rats. Scale bar = 5 μm. N Spine density did not differ between groups regardless of subclass. However, Shock-exposed rats exhibited significantly greater spine neck diameter O and shorter spine length P across all subtypes (main effect of shock) relative to rats exposed to the neutral testing context. *p ≤ 0.05.