To survive in a dynamic environment, animals need to identify and appropriately respond to stimuli that signal danger 1 . Survival also depends on suppressing the threat-response during a stimulus that predicts absence of threat, i.e. safety 2 – 5 . Understanding the biological substrates of emotional memories in which animals learn to flexibly execute defensive responses to a threat-predictive cue and a safety cue is critical for developing treatments for memory disorders such as PTSD 5 . A key brain area for processing and storing threat memories is the centrolateral amygdala (CeL), which is an important node in the neuronal circuit mediating defensive responses 6 – 9 . Here, we applied intersectional chemogenetic strategies in CeL inhibitory neurons (INs) to block cell-type-specific translation programs that are sensitive to depletion of eukaryotic initiation factor 4E (eIF4E) and phosphorylation of eukaryotic initiation factor 2α (p-eIF2α), respectively. We show that de novo translation in CeL Somatostatin-expressing (SOM) INs is necessary for long-term storage of conditioned-threat response whereas de novo translation in CeL protein kinase Cδ (PKCδ)-expressing INs is necessary for conditioned-response inhibition to a safety cue. Our results provide new insight into the role of de novo protein synthesis in distinct CeL inhibitory neuron populations during consolidation of long-term memories.

14 15To survive in a dynamic environment, animals need to identify and appropriately respond to 16 stimuli that signal danger 1,2 . At the same time, animal survival also depends on suppressing the 17 threat response during a stimulus that predicts absence of threat, i.e. safety 3-5 . Understanding the 18 biological substrates of differential threat memories in which animals learn to flexibly switch 19 between expressing and suppressing defensive responses to a threat-predictive cue and a safety 20 cue, respectively, is critical for developing treatments for memory disorders such as PTSD 6 . A key 21 brain area for processing and storing threat memories is the centrolateral amygdala (CeL), which 22 receives convergent sensory inputs from the parabrachial nucleus and the basolateral amygdala 23 and connects directly to the output nucleus of amygdala, the centromedial nucleus, to mediate 24 defensive responses 7-9 . Despite a plethora of studies on the importance of neuronal activity in 25 specific CeL neuronal populations during memory acquisition and retrieval 10-12 , little is known 26 about regulation of their protein synthesis machinery. Consolidation of long-term, but not short-27 term, threat memories requires de novo protein synthesis, which suggests that the translation 28 machinery in CeL interneurons is tightly regulated in order to stabilize associative memories. 29Herein, we have applied intersectional chemogenetic strategies in CeL interneurons to block cell 30 type-specific translation initiation programs that are sensitive to depletion of eukaryotic initiation 31 factor 4E (eIF4E) and phosphorylation of eukaryotic initiation factor 2 (p-eIF2 ), respectively. We 32show that in a differential threat conditioning paradigm, de novo translation in somatostatin-33 expressing (SOM) interneurons in the CeL is necessary for long-term storage of conditioned threat 34 response whereas de novo translation in protein kinase C -expressing (PKC ) interneurons in the 35 CeL is essential for storing conditioned response inhibition to a safety cue. Further, we show that 36 oxytocinergic neuromodulation of PKC interneurons during differential threat learning is 37 2 important for long-lasting cued threat discrimination. Our results indicate that the molecular 38 elements of a differential threat memory trace are compartmentalized in distinct CeL interneuron 39 populations and provide new mechanistic insight into the role of de novo protein synthesis in 40 consolidation of long-term memories. 42Neurons have evolved to both respond dynamically to their environment at millisecond time scales 43 and yet can store information stably for a much longer period of time. The latter mode of stabilizing 44 information in mnemonic processes requires de novo translation 13,14 . Tight regulation of translation occurs 45 during initiation where the two major rate-limiting steps are the assembly of the eIF2-tRNA i Met ternary 46 complex and the m7 GpppN cap-binding complex 15 . Bidirectional control of protein synthesis can be 47 med...