Retrosplenial cortex inactivation during retrieval, but not encoding, impairs remotely acquired auditory fear conditioning in male rats

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The retrosplenial cortex (RSC) is well-known for its contribution to episodic memory, as well as contextual and spatial learning and memory. However, two literatures have also emerged examining the role of the RSC in aversive conditioning. The purpose of this manuscript is to review, and attempt to integrate, these two literatures. We focus on studies in which discrete cues, such as tones, predict the occurrence of aversive outcomes, such as mild shocks. Using both electrophysiological recordings and lesion methods, the first literature has examined RSC contributions to discriminative avoidance conditioning. The second, and more recent literature, has focused on the role of the RSC in Pavlovian fear conditioning. We discuss both literatures in terms of the type of information processed by the RSC, the role of the RSC in memory storage, and how the aversive conditioning literature might be consistent with a role for the RSC in contextual learning and memory.

Section: Delay Fear Conditioningsupporting

confidence: 77%

Retrosplenial cortex and aversive conditioning

Cheng,

Fournier,

Todd

2024

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“…Previous reports have shown that the RSC is involved in the retrieval of aversive memories (Fournier et al, 2021), including those assessed by the IA task (Katche et al, 2013). Thus, we aimed to investigate the potential involvement of the cholinergic system, specifically through α7 nAChRs, in mediating that function.…”

Section: Discussionmentioning

confidence: 96%

Dual role of α7 nicotinic acetylcholine receptors in the retrosplenial cortex for aversive memory acquisition and retrieval

Pastor,

Katche

2024

In the retrosplenial cortex (RSC), the role of cholinergic modulation via α7 nicotinic receptors and their involvement in memory is unknown. In recent years, the RSC has been shown to deteriorate in the early stages of Alzheimer’s disease (AD). Likewise, the cholinergic system has been postulated as one of those responsible for cognitive impairment in patients with AD. Great interest has arisen in the study of α7 nicotinic receptors as more specific targets for the treatment of this disease. For this reason, we aim to study the role of α7 receptors of the RSC in memory processing. We infused a selective α7 receptor antagonist into the anterior part of the RSC (aRSC) to assess its role in different phases of aversive memory processing using an inhibitory avoidance task. We found that α7 nicotinic receptors are involved in memory acquisition and expression, but not in its consolidation. These results identify aRSC α7 nicotinic receptors as key players in aversive memory processing and highlight their significant potential as therapeutic targets for Alzheimer’s disease.

“…It appears that a number of cortical regions, including the medial prefrontal (and the richly associated thalamic nucleus reuniens), cingulate, and retrosplenial cortex, are all critically involved in systems consolidation and the recall of remote context fear memories (e.g., Frankland and Bontempi, 2005 ; Corcoran et al, 2011 ; Katche et al, 2013a , b ; Todd and Bucci, 2015 ; Kitamura et al, 2017 ; de Sousa et al, 2019 ; Fournier et al, 2021 ). Of possibly special interest is the retrosplenial cortex, which is intimately connected with both cortical and hippocampal areas that appear to participate in systems consolidation and where manipulations during the period when systems consolidation is occurring can have significant effects on the process ( Katche et al, 2013a , b ; de Sousa et al, 2019 ).…”

Section: Discussionmentioning

confidence: 99%

Remote memory in a Bayesian model of context fear conditioning (BaconREM)

Krasne,

Fanselow

2024

Here, we propose a model of remote memory (BaconREM), which is an extension of a previously published Bayesian model of context fear learning (BACON) that accounts for many aspects of recently learned context fear. BaconREM simulates most known phenomenology of remote context fear as studied in rodents and makes new predictions. In particular, it predicts the well-known observation that fear that was conditioned to a recently encoded context becomes hippocampus-independent and shows much-enhanced generalization (“hyper-generalization”) when systems consolidation occurs (i.e., when memory becomes remote). However, the model also predicts that there should be circumstances under which the generalizability of remote fear may not increase or even decrease. It also predicts the established finding that a “reminder” exposure to a feared context can abolish hyper-generalization while at the same time making remote fear again hippocampus-dependent. This observation has in the past been taken to suggest that reminders facilitate access to detail memory that remains permanently in the hippocampus even after systems consolidation is complete. However, the present model simulates this result even though it totally moves all the contextual memory that it retains to the neo-cortex when context fear becomes remote.