Probing subicular inputs to the medial prefrontal cortex

The hippocampal formation is anatomically and functionally divided into a dorsal and a ventral part, being involved in processing cognitive tasks and emotional stimuli, respectively. The ventral subiculum as part of the hippocampal formation projects to the medial prefrontal cortex (mPFC), but only very little is known about connections arising from the dorsal SUB (dSUB). Here, we investigate the dSUB to mPFC connectivity in acute brain slices using electrophysiology and optogenetics. We show that the anterior cingulate cortex (ACC) is the main target of dorsal subicular projections to the mPFC, with no preference between excitatory or inhibitory neurons. In addition to superficial neurons in the ACC, the prelimbic and infralimbic PFC are also targeted by subicular fibers. Thus, these novel region- and layer-specific connections between the dSUB and the prefrontal cortices challenge existing anatomical data and refine the hippocampocortical wiring diagram.

Automated summary

The hippocampal formation is anatomically and functionally divided into a dorsal and a ventral part involved in processing cognitive tasks and emotional stimuli, respectively. While the ventral subiculum projects to the medial prefrontal cortex, the dorsal subiculum targets the anterior cingulate cortex and other areas of the prefrontal cortex with both excitatory and inhibitory neurons. These novel connections challenge existing anatomical data and refine the hippocampocortical wiring diagram.