Nucleus Reuniens Is Required for Encoding and Retrieving Precise, Hippocampal-Dependent Contextual Fear Memories in Rats

• DOI: 10.1523/jneurosci.1429-18.2018
• Publication Date: 2018-10-03T19:05:44Z
• Authors: Karthik R. Ramana...; Reed L. Ressler; Jingji Jin; Stephen Maren
• Keywords: Muscimol; Freezing behavior

The nucleus reuniens (RE) is a ventral midline thalamic that interconnects the medial prefrontal cortex (mPFC) and hippocampus (HPC). Considerable data indicate HPC–mPFC circuits are involved in contextual spatial memory; however, it not clear whether RE mediates acquisition or retrieval of these memories. To examine this question, we inactivated with muscimol before either pavlovian fear conditioning rats; freezing served as index fear. We found inactivation impaired freezing, whereas testing increased generalization to novel context; did affect expression auditory conditioning. Interestingly, impairments were absent when was also conducted after inactivation. Contextual memories acquired under hippocampal independent, insofar rats conditioned insensitive intrahippocampal infusions NMDA receptor antagonist aminophosphonovalerate. Together, reveal supports hippocampal-dependent encoding precise allow discrimination dangerous contexts from safe contexts. When inactive, alternate neural systems acquire an impoverished memory expressed only off-line. SIGNIFICANCE STATEMENT coordinates communication between cortex, brain areas critical for memory. Here show temporary pharmacological impairs precision rats. However, inactivating restored Critically, imprecise learned independently hippocampus. These required support