Prefrontal-raphe-habenular circuit drives fear memory recall and updating

Here, we identify a fear recall pathway. We found that hippocampal and amygdalar memory centers directly target a group of medial prefrontal cortex (mPFC) neurons, which are necessary for fear recall and directly target vesicular glutamate transporter 2 (vGluT2)-expressing neurons in the pontine median raphe region (MRRvGluT2 neurons) in mice.

We found that MRRvGluT2 neurons are necessary for recalling contextual and cued fear memories, they exhibit scalable fear-dependent activity, bidirectionally regulate depression-like behaviors, and show prolonged activity after a fearful experience. During fear memory recall, MRRvGluT2 neurons activate the lateral habenula (LHb), a region implicated in major depression. MRRvGluT2 neurons are electrophysiologically and genetically diverse, and present in rodent and primate species.