Project Summary and Abstract Fear and trauma-related disorders affect millions of people in the United States and throughout the world each year. While the symptomatology in these disorders is well-characterized, the neural circuits which encode trauma are not. This proposal will provide a critical insight into these circuits by dissecting how a discrete pathway from the ventral hippocampus to the hypothalamus controls fear memories. Aim 1 will use cutting- edge retrograde viral targeting techniques along with chemogenetics to elucidate how silencing this circuit modulates fear memories in males and females. Aim 2 will use the same retrograde viral strategy from Aim 1 along with a genetically encoded calcium indicator and fiber photometry to reveal how circuit activity shifts from fear acquisition to fear memory retrieval. Aim 3 will examine how silencing this circuit alters trans-synaptic transcriptional activity in the hypothalamus. This proposal will reveal a novel neural circuit mechanism for fear memories. It will provide fundamental insights into a high-value target for innovative treatments of fear and trauma-related disorders.