Nucleus Reuniens Is Required for Encoding and Retrieving Precise, Hippocampal-Dependent Contextual Fear Memories in Rats
| Autor: | Jingji Jin, Karthik R. Ramanathan, Reed L. Ressler, Stephen Maren |
|---|---|
| Rok vydání: | 2018 |
| Předmět: |
0301 basic medicine
Male Thalamus Midline Thalamic Nuclei Hippocampus Context (language use) Hippocampal formation 03 medical and health sciences chemistry.chemical_compound Random Allocation 0302 clinical medicine Animals Rats Long-Evans Fear conditioning Prefrontal cortex Research Articles 030304 developmental biology Spatial Memory 0303 health sciences General Neuroscience Fear Rats 030104 developmental biology Muscimol chemistry Acoustic Stimulation Mental Recall Conditioning Nucleus reuniens Nerve Net Psychology Neuroscience 030217 neurology & neurosurgery |
| Zdroj: | The Journal of neuroscience : the official journal of the Society for Neuroscience. 38(46) |
| ISSN: | 1529-2401 |
| Popis: | The nucleus reuniens (RE) is a ventral midline thalamic nucleus that interconnects the medial prefrontal cortex (mPFC) and hippocampus (HPC). Considerable data indicate that HPC-mPFC circuits are involved in contextual and spatial memory; however, it is not clear whether the RE mediates the acquisition or retrieval of these memories. To examine this question, we inactivated the RE with muscimol before either the acquisition or retrieval of Pavlovian fear conditioning in rats; freezing served as the index of fear. We found that RE inactivation before conditioning impaired the acquisition of contextual freezing, whereas inactivation of the RE prior to retrieval testing increased the generalization of freezing to a novel context; inactivation of the RE did not affect either the acquisition or expression of auditory fear conditioning. Interestingly, contextual conditioning impairments were absent when retrieval testing was also conducted after RE inactivation. Contextual memories acquired under RE inactivation were hippocampal-independent, insofar as contextual freezing in rats conditioned under RE inactivation was insensitive to intra-hippocampal infusions of the NMDA receptor antagonist, D,L-amino-5-phosophonovaleric acid (APV). Together, these data reveal that the RE supports hippocampal-dependent encoding of precise contextual memories that allow discrimination of dangerous from safe contexts. When the RE is inactive, however, alternate neural systems acquire an impoverished contextual memory that is only expressed when the RE is offline.SIGNIFICANCE STATEMENTThe midline thalamic nucleus reuniens (RE) coordinates communication between the hippocampus and medial prefrontal cortex, brain areas critical for contextual and spatial memory. Here we show that temporary pharmacological inactivation of RE impairs the acquisition and precision of contextual fear memories after Pavlovian fear conditioning in rats. However, inactivating the RE prior to retrieval testing restored contextual memory in rats conditioned after RE inactivation. Critically, we show that imprecise contextual memories acquired under RE inactivation are learned independently of the hippocampus. These data reveal that the RE is required for hippocampal-dependent encoding of precise contextual memories to support the discrimination of safe and dangerous contexts. |
| Databáze: | OpenAIRE |
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