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Cruz AS, Cruz S, Remondes M. Effects of optogenetic silencing the anterior cingulate cortex in a delayed non-match to trajectory task. OXFORD OPEN NEUROSCIENCE 2024; 3:kvae002. [PMID: 38595941 PMCID: PMC10939314 DOI: 10.1093/oons/kvae002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2023] [Revised: 01/16/2024] [Accepted: 01/19/2024] [Indexed: 04/11/2024]
Abstract
Working memory is a fundamental cognitive ability, allowing us to keep information in memory for the time needed to perform a given task. A complex neural circuit fulfills these functions, among which is the anterior cingulate cortex (CG). Functionally and anatomically connected to the medial prefrontal, retrosplenial, midcingulate and hippocampus, as well as motor cortices, CG has been implicated in retrieving appropriate information when needed to select and control appropriate behavior. The role of cingulate cortex in working memory-guided behaviors remains unclear due to the lack of studies reversibly interfering with its activity during specific epochs of working memory. We used eNpHR3.0 to silence cingulate neurons while animals perform a standard delayed non-match to trajectory task, and found that, while not causing an absolute impairment in working memory, silencing cingulate neurons during retrieval decreases the mean performance if compared to silencing during encoding. Such retrieval-associated changes are accompanied by longer delays observed when light is delivered to control animals, when compared to eNpHR3.0+ ones, consistent with an adaptive recruitment of additional cognitive resources.
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Affiliation(s)
- Ana S Cruz
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina Universidade de Lisboa, Lisbon 1649-028, Portugal
| | - Sara Cruz
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina Universidade de Lisboa, Lisbon 1649-028, Portugal
| | - Miguel Remondes
- Instituto de Medicina Molecular João Lobo Antunes, Faculdade de Medicina Universidade de Lisboa, Lisbon 1649-028, Portugal
- Faculdade de Medicina Veterinária Universidade Lusófona, Lisbon 1749-024, Portugal
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Awad W, Kritman M, Ferreira G, Maroun M. Differential Recruitment of the Infralimbic Cortex in Recent and Remote Retrieval and Extinction of Aversive Memory in Post-Weanling Rats. Int J Neuropsychopharmacol 2022; 25:489-497. [PMID: 35134947 PMCID: PMC9211009 DOI: 10.1093/ijnp/pyac012] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 12/28/2021] [Accepted: 02/01/2022] [Indexed: 11/29/2022] Open
Abstract
BACKGROUND We previously showed that the infralimbic medial prefrontal cortex (IL-mPFC) plays an important role in recent and remote memory retrieval and extinction of conditioned odor aversion (COA) and contextual fear conditioning (CFC) in adult rats. Because the mPFC undergoes maturation during post-weaning, here, we aimed to explore (1) whether post-weanling rats can form recent and remote COA and CFC memory, and (2) the role of the IL-mPFC in mediating these processes. METHODS To investigate the retrieval process, we transiently inactivated the IL-mPFC with lidocaine prior to the retrieval test at either recent or remote time points. To target the consolidation process, we applied the protein synthesis inhibitor after the retrieval at recent or remote time points. RESULTS Our results show that the post-weanling animals were able to develop both recent and remote memory of both COA and CFC. IL-mPFC manipulations had no effect on retrieval or extinction of recent and remote COA memory, suggesting that the IL has no effect in COA at this developmental stage. In contrast, the IL-mPFC played a role in (1) the extinction of recent, but not remote, CFC memory, and (2) the retrieval of remote, but not recent, CFC memory. Moreover, remote, but not recent, CFC retrieval enhanced c-Fos protein expression in the IL-mPFC. CONCLUSIONS Altogether, these results point to a differential role of the IL-mPFC in recent and remote CFC memory retrieval and extinction and further confirm the differences in the role of IL-mPFC in these processes in post-weanling and adult animals.
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Affiliation(s)
| | | | | | - Mouna Maroun
- Correspondence: Mouna Maroun, PhD, Department of Neurobiology, Faculty of Natural Sciences, University of Haifa, Haifa 31095, Israel ()
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Polarity-specific high-definition transcranial direct current stimulation of the anterior and posterior default mode network improves remote memory retrieval. Brain Stimul 2021; 14:1005-1014. [PMID: 34182233 DOI: 10.1016/j.brs.2021.06.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Revised: 06/10/2021] [Accepted: 06/15/2021] [Indexed: 01/23/2023] Open
Abstract
BACKGROUND Previous studies show that activity in the posterior default mode network (pDMN), including the posterior cingulate cortex and the precuneus, is correlated with the success of long-term episodic memory retrieval. However, the role of the anterior DMN (aDMN) including the medial prefrontal cortex is still unclear. Some studies show that activating the medial prefrontal cortex improves memory retrieval while other studies show deactivation of the medial prefrontal cortex in successful retrieval of episodic memories, suggesting a possible functional dissociation between the aDMN and pDMN. OBJECTIVE In the current study, we aim to causally explore this probable dissociation using high-definition transcranial direct current stimulation (HD-tDCS). METHODS We perform a randomised double-blinded two-visit placebo-controlled study with 84 healthy young adults. During Visit 1 they learn 75 Swahili-English word-associations. Seven days later, they randomly receive either anodal, cathodal or sham HD-tDCS targeting the pDMN or aDMN while they recall what they have previously learned. RESULTS We demonstrate that anodal stimulation of the pDMN and cathodal stimulation of the aDMN, equally improve the percentage of Swahili-English word-associations recalled 7 days after learning. CONCLUSIONS Modulating the activity in the aDMN and pDMN causally affect memory retrieval performance. HD-tDCS of the aDMN and pDMN shows that anodal stimulation of the pDMN and cathodal stimulation of the aDMN increases memory retrieval performance one week after the learning phase. Given consistent evidence, it is highly likely that we are increasing the activity in the pDMN with anodal pDMN stimulation. However, it is not clear if cathodal HD-tDCS targetting aDMN works via decoupling from the pDMN or via indirectly disinhibit pDMN.
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Kol A, Adamsky A, Groysman M, Kreisel T, London M, Goshen I. Astrocytes contribute to remote memory formation by modulating hippocampal-cortical communication during learning. Nat Neurosci 2020; 23:1229-1239. [PMID: 32747787 PMCID: PMC7611962 DOI: 10.1038/s41593-020-0679-6] [Citation(s) in RCA: 151] [Impact Index Per Article: 37.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 06/26/2020] [Indexed: 12/15/2022]
Abstract
Remote memories depend on coordinated activity in the hippocampus and frontal cortices, but the timeline of these interactions is debated. Astrocytes sense and modify neuronal activity, but their role in remote memory was scarcely explored. We expressed the Gi-coupled receptor hM4Di in CA1 astrocytes, and discovered that astrocytic manipulation during learning specifically impaired remote, but not recent, memory recall, and decreased activity in the anterior cingulate cortex (ACC) during retrieval. We revealed massive recruitment of ACC-projecting CA1 neurons during memory acquisition, accompanied by activation of ACC neurons. Astrocytic Gi activation disrupted CA3 to CA1 communication in-vivo, and reduced the downstream response in ACC. In behaving mice, it induced a projection-specific inhibition of CA1-to-ACC neurons during learning, consequently preventing ACC recruitment. Finally, direct inhibition of CA1-to-ACC projecting neurons spared recent and impaired remote memory. Our findings suggest that remote memory acquisition involves projection-specific functions of astrocytes in regulating CA1-to-ACC neuronal communication.
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Affiliation(s)
- Adi Kol
- Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Adar Adamsky
- Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Maya Groysman
- ELSC Vector Core Facility, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Tirzah Kreisel
- Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Michael London
- Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem, Israel.,Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Inbal Goshen
- Edmond and Lily Safra Center for Brain Sciences (ELSC), The Hebrew University of Jerusalem, Jerusalem, Israel.
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Peeters LM, Hinz R, Detrez JR, Missault S, De Vos WH, Verhoye M, Van der Linden A, Keliris GA. Chemogenetic silencing of neurons in the mouse anterior cingulate area modulates neuronal activity and functional connectivity. Neuroimage 2020; 220:117088. [PMID: 32592851 DOI: 10.1016/j.neuroimage.2020.117088] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2020] [Revised: 06/14/2020] [Accepted: 06/22/2020] [Indexed: 01/05/2023] Open
Abstract
The anterior cingulate area (ACC) is an integral part of the prefrontal cortex in mice and supports cognitive functions, including attentional processes, motion planning and execution as well as remote memory, fear and pain. Previous anatomical and functional imaging studies demonstrated that the ACC is interconnected with numerous brain regions, such as motor and sensory cortices, amygdala and limbic areas, suggesting it serves as a hub in functional networks. However, the exact role of the ACC in regulating functional network activity and connectivity remains to be elucidated. Recently developed neuromodulatory techniques, such as Designer Receptors Exclusively Activated by Designer Drugs (DREADDs) allow for precise control of neuronal activity. In this study, we used an inhibitory kappa-opioid receptor DREADD (KORD) to temporally inhibit neuronal firing in the right ACC of mice and assessed functional network activity and connectivity using non-invasive functional magnetic resonance imaging (MRI). We demonstrated that KORD-induced inhibition of the right ACC induced blood oxygenation-level dependent (BOLD) signal decreases and increases in connected brain regions of both hemispheres. More specifically, altered neuronal activity could be observed in functional brain networks including connections with sensory cortex, thalamus, basolateral amygdala and ventral pallidum, areas involved in attention processes, working memory, fear behavior and reward respectively. Furthermore, these modulations in neuronal activity were associated with decreased intra- and interhemispheric functional connectivity. Our results consolidate the hub role of the mouse ACC in functional networks and further demonstrate that the combination of the DREADD technology and non-invasive functional imaging methods is a valuable tool for unraveling mechanisms of network function and dysfunction by reversible inactivation of selected targets.
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Affiliation(s)
- Lore M Peeters
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
| | - Rukun Hinz
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
| | - Jan R Detrez
- Laboratory for Cell Biology and Histology, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
| | - Stephan Missault
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
| | - Winnok H De Vos
- Laboratory for Cell Biology and Histology, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
| | - Marleen Verhoye
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium
| | | | - Georgios A Keliris
- Bio-Imaging Lab, University of Antwerp, Universiteitsplein 1, 2610, Wilrijk, Belgium.
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Lee J, Lee HR, Kim JI, Baek J, Jang EH, Lee J, Kim M, Lee RU, Kim S, Park P, Kaang BK. Transient cAMP elevation during systems consolidation enhances remote contextual fear memory. Neurobiol Learn Mem 2020; 169:107171. [PMID: 31978552 DOI: 10.1016/j.nlm.2020.107171] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2019] [Revised: 12/31/2019] [Accepted: 01/19/2020] [Indexed: 11/30/2022]
Abstract
Memory is stored in our brains over a temporally graded transition. With time, recently formed memories are transformed into remote memories for permanent storage; multiple brain regions, such as the hippocampus and neocortex, participate in this process. In this study, we aimed to understand the molecular mechanism of systems consolidation of memory and to investigate the brain regions that contribute to this regulation. We first carried out a contextual fear memory test using a transgenic mouse line, which expressed exogenously-derived Aplysia octopamine receptors in the forebrain region, such that, in response to octopamine treatment, cyclic adenosine monophosphate (cAMP) levels could be transiently elevated. From this experiment, we revealed that transient elevation of cAMP levels in the forebrain during systems consolidation led to an enhancement in remote fear memory and increased miniature excitatory synaptic currents in layer II/III of the anterior cingulate cortex (ACC). Furthermore, using an adeno-associated-virus-driven DREADD system, we investigated the specific regions in the forebrain that contribute to the regulation of memory transfer into long-term associations. Our results implied that transient elevation of cAMP levels was induced chemogenetically in the ACC, but not in the hippocampus, and showed a significant enhancement of remote memory. This finding suggests that neuronal activation during systems consolidation through the elevation of cAMP levels in the ACC contributes to remote memory enhancement.
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Affiliation(s)
- Jaehyun Lee
- Interdisciplinary Program in Neuroscience, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, Republic of Korea; Neurobiology Laboratory, Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanangno 599, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Hye-Ryeon Lee
- Neurobiology Laboratory, Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanangno 599, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Jae-Ick Kim
- Neurobiology Laboratory, Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanangno 599, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Jinhee Baek
- Neurobiology Laboratory, Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanangno 599, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Eun-Hae Jang
- Neurobiology Laboratory, Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanangno 599, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Jihye Lee
- Neurobiology Laboratory, Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanangno 599, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Myeongwon Kim
- Neurobiology Laboratory, Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanangno 599, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Ro Un Lee
- Neurobiology Laboratory, Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanangno 599, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Somi Kim
- Neurobiology Laboratory, Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanangno 599, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Pojeong Park
- Neurobiology Laboratory, Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanangno 599, Gwanak-Gu, Seoul 08826, Republic of Korea
| | - Bong-Kiun Kaang
- Interdisciplinary Program in Neuroscience, Seoul National University, 1 Gwanangno, Gwanak-gu, Seoul 08826, Republic of Korea; Neurobiology Laboratory, Department of Biological Sciences, College of Natural Sciences, Seoul National University, Gwanangno 599, Gwanak-Gu, Seoul 08826, Republic of Korea.
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7
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Helfer P, Shultz TR. A computational model of systems memory consolidation and reconsolidation. Hippocampus 2019; 30:659-677. [PMID: 31872960 DOI: 10.1002/hipo.23187] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2019] [Revised: 10/05/2019] [Accepted: 12/04/2019] [Indexed: 12/27/2022]
Abstract
In the mammalian brain, newly acquired memories depend on the hippocampus (HPC) for maintenance and recall, but over time, the neocortex takes over these functions, rendering memories HPC-independent. The process responsible for this transformation is called systems memory consolidation. Reactivation of a well-consolidated memory can trigger a temporary return to a HPC-dependent state, a phenomenon known as systems memory reconsolidation. The neural mechanisms underlying systems memory consolidation and reconsolidation are not well understood. Here, we propose a neural model based on well-documented mechanisms of synaptic plasticity and stability and describe a computational implementation that demonstrates the model's ability to account for a range of findings from the systems consolidation and reconsolidation literature. We derive several predictions from the computational model and suggest experiments that may test its validity.
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Affiliation(s)
- Peter Helfer
- Department of Psychology, McGill University, 2001 McGill College, Montreal, QC, Canada
| | - Thomas R Shultz
- Department of Psychology, McGill University, 2001 McGill College, Montreal, QC, Canada
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8
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Wirt RA, Hyman JM. ACC Theta Improves Hippocampal Contextual Processing during Remote Recall. Cell Rep 2019; 27:2313-2327.e4. [DOI: 10.1016/j.celrep.2019.04.080] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2019] [Revised: 03/18/2019] [Accepted: 04/17/2019] [Indexed: 12/27/2022] Open
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9
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Quillfeldt JA. Temporal Flexibility of Systems Consolidation and the Synaptic Occupancy/Reset Theory (SORT): Cues About the Nature of the Engram. Front Synaptic Neurosci 2019; 11:1. [PMID: 30814946 PMCID: PMC6381034 DOI: 10.3389/fnsyn.2019.00001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 01/14/2019] [Indexed: 11/24/2022] Open
Abstract
The ability to adapt to new situations involves behavioral changes expressed either from an innate repertoire, or by acquiring experience through memory consolidation mechanisms, by far a much richer and flexible source of adaptation. Memory formation consists of two interrelated processes that take place at different spatial and temporal scales, Synaptic Consolidation, local plastic changes in the recruited neurons, and Systems Consolidation, a process of gradual reorganization of the explicit/declarative memory trace between hippocampus and the neocortex. In this review, we summarize some converging experimental results from our lab that support a normal temporal framework of memory systems consolidation as measured both from the anatomical and the psychological points of view, and propose a hypothetical model that explains these findings while predicting other phenomena. Then, the same experimental design was repeated interposing additional tasks between the training and the remote test to verify for any interference: we found that (a) when the animals were subject to a succession of new learnings, systems consolidation was accelerated, with the disengagement of the hippocampus taking place before the natural time point of this functional switch, but (b) when a few reactivation sessions reexposed the animal to the training context without the shock, systems consolidation was delayed, with the hippocampus prolonging its involvement in retrieval. We hypothesize that new learning recruits from a fixed number of plastic synapses in the CA1 area to store the engram index, while reconsolidation lead to a different outcome, in which additional synapses are made available. The first situation implies the need of a reset mechanism in order to free synapses needed for further learning, and explains the acceleration observed under intense learning activity, while the delay might be explained by a different process, able to generate extra free synapses: depending on the cognitive demands, it deals either with a fixed or a variable pool of available synapses. The Synaptic Occupancy/Reset Theory (SORT) emerged as an explanation for the temporal flexibility of systems consolidation, to encompass the two different dynamics of explicit memories, as well as to bridge both synaptic and systems consolidation in one single mechanism.
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Affiliation(s)
- Jorge Alberto Quillfeldt
- Psychobiology and Neurocomputation Lab, Department of Biophysics, Institute of Biosciences, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.,Neurosciences Graduate Program, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.,Department of Psychology, McGill University, Montreal, QC, Canada
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10
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Adams JM, Pei H, Sandoval DA, Seeley RJ, Chang RB, Liberles SD, Olson DP. Liraglutide Modulates Appetite and Body Weight Through Glucagon-Like Peptide 1 Receptor-Expressing Glutamatergic Neurons. Diabetes 2018; 67:1538-1548. [PMID: 29776968 PMCID: PMC6054439 DOI: 10.2337/db17-1385] [Citation(s) in RCA: 63] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 05/06/2018] [Indexed: 12/18/2022]
Abstract
Glucagon-like peptide 1 receptor (GLP-1R) agonists are U.S. Food and Drug Administration-approved weight loss drugs. Despite their widespread use, the sites of action through which GLP-1R agonists (GLP1RAs) affect appetite and body weight are still not fully understood. We determined whether GLP-1Rs in either GABAergic or glutamatergic neurons are necessary for the short- and long-term effects of the GLP1RA liraglutide on food intake, visceral illness, body weight, and neural network activation. We found that mice lacking GLP-1Rs in vGAT-expressing GABAergic neurons responded identically to controls in all parameters measured, whereas deletion of GLP-1Rs in vGlut2-expressing glutamatergic neurons eliminated liraglutide-induced weight loss and visceral illness and severely attenuated its effects on feeding. Concomitantly, deletion of GLP-1Rs from glutamatergic neurons completely abolished the neural network activation observed after liraglutide administration. We conclude that liraglutide activates a dispersed but discrete neural network to mediate its physiological effects and that these effects require GLP-1R expression on glutamatergic but not GABAergic neurons.
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Affiliation(s)
- Jessica M Adams
- Department of Pediatrics, University of Michigan, Ann Arbor, MI
| | - Hongjuan Pei
- Department of Pediatrics, University of Michigan, Ann Arbor, MI
| | | | - Randy J Seeley
- Department of Surgery, University of Michigan, Ann Arbor, MI
| | - Rui B Chang
- Department of Cell Biology, Harvard Medical School, Boston, MA
| | | | - David P Olson
- Department of Pediatrics, University of Michigan, Ann Arbor, MI
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The Rhesus Monkey Hippocampus Critically Contributes to Scene Memory Retrieval, But Not New Learning. J Neurosci 2018; 38:7800-7808. [PMID: 30049888 DOI: 10.1523/jneurosci.0832-18.2018] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Revised: 07/21/2018] [Accepted: 07/23/2018] [Indexed: 12/11/2022] Open
Abstract
Humans can recall a large number of memories years after the initial events. Patients with amnesia often have lesions to the hippocampus, but human lesions are imprecise, making it difficult to identify the anatomy underlying memory impairments. Rodent studies enable great precision in hippocampal manipulations, but not investigation of many interleaved memories. Thus it is not known how lesions restricted to the hippocampus affect the retrieval of multiple sequentially encoded memories. Furthermore, disagreement exists as to whether hippocampal inactivations lead to temporally graded or ungraded amnesia, which could be a consequence of differences between rodent and human studies. In the current study, rhesus monkeys of both sexes received either bilateral neurotoxic hippocampal lesions or remained unoperated controls and were tested on recognition and new learning of visual object-in-place scenes. Monkeys with hippocampal lesions were significantly impaired at remembering scenes that were encoded before the lesion. We did not observe any temporal gradient effect of the lesion on memory recognition, with recent and remote memories being equally affected by the lesion. Monkeys with hippocampal lesions showed no deficits in learning new scenes. Thus, the hippocampus, like other cortical regions, may be engaged in the acquisition and storage of new memories, but the role of the damaged hippocampus can be taken over by spared hippocampal tissue or extra-hippocampal regions following a lesion. These findings illustrate the utility of experimental paradigms for studying retrograde and anterograde amnesia that make use of the capacity of nonhuman primates to rapidly acquire many distinct visual memories.SIGNIFICANCE STATEMENT Recalling old memories, creating new memories, and the process by which memories transition from temporary to permanent storage all may rely on the hippocampus. Whether the hippocampus is necessary for encoding and retrieval of multiple related visual memories in primates is not known. Monkeys that learned many visual memory problems before precise lesions of the hippocampus were impaired at recalling those memories after hippocampal damage regardless of when the memories were formed, but could learn new memory problems at a normal rate. This suggests the hippocampus is normally vital for retrieval of complex visual memories regardless of their age, and also points to the importance of investigating mechanisms by which memories may be acquired in the presence of hippocampal damage.
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12
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Barry DN, Chadwick MJ, Maguire EA. Nonmonotonic recruitment of ventromedial prefrontal cortex during remote memory recall. PLoS Biol 2018; 16:e2005479. [PMID: 29965966 PMCID: PMC6044544 DOI: 10.1371/journal.pbio.2005479] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Revised: 07/13/2018] [Accepted: 06/18/2018] [Indexed: 11/25/2022] Open
Abstract
Systems-level consolidation refers to the time-dependent reorganisation of memory traces in the neocortex, a process in which the ventromedial prefrontal cortex (vmPFC) has been implicated. Capturing the precise temporal evolution of this crucial process in humans has long proved elusive. Here, we used multivariate methods and a longitudinal functional magnetic resonance imaging (fMRI) design to detect, with high granularity, the extent to which autobiographical memories of different ages were represented in vmPFC and how this changed over time. We observed an unexpected time course of vmPFC recruitment during retrieval, rising and falling around an initial peak of 8–12 months, before reengaging for older 2- and 5-year-old memories. This pattern was replicated in 2 independent sets of memories. Moreover, it was further replicated in a follow-up study 8 months later with the same participants and memories, for which the individual memory representations had undergone their hypothesised strengthening or weakening over time. We conclude that the temporal engagement of vmPFC in memory retrieval seems to be nonmonotonic, revealing a complex relationship between systems-level consolidation and prefrontal cortex recruitment that is unaccounted for by current theories. Our past experiences are captured in autobiographical memories that allow us to recollect events from our lives long after they originally occurred. A part of the brain’s frontal lobe, called the ventromedial prefrontal cortex (vmPFC), is known to be important for supporting autobiographical memories, especially as memories become more remote. The precise temporal profile of the vmPFC’s involvement is unclear, yet this information is vital if we are to understand how memories change over time and the mechanisms involved. In this study, we sought to establish the time course of vmPFC engagement in the recollection of autobiographical memories while participants recalled memories of different ages during functional magnetic resonance imaging (fMRI). Using a method that detects the brain activity patterns associated with individual memories, we found that memory-specific neural patterns in vmPFC became more distinct over the first few months after a memory was formed, but then this initial involvement of vmPFC subsided after 1 year. However, more remote memories (2 years and older) appeared to reengage vmPFC once again. This temporal profile is difficult to accommodate within any single existing theory. Consequently, our results provoke a rethink about how memories evolve over time and the role played by the vmPFC.
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Affiliation(s)
- Daniel N. Barry
- Wellcome Centre for Human Neuroimaging, Institute of Neurology, University College London, London, United Kingdom
| | - Martin J. Chadwick
- Institute of Behavioural Neuroscience, Department of Experimental Psychology, Division of Psychology and Language Sciences, University College London, London, United Kingdom
| | - Eleanor A. Maguire
- Wellcome Centre for Human Neuroimaging, Institute of Neurology, University College London, London, United Kingdom
- * E-mail:
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13
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Crestani AP, Sierra RO, Machado A, Haubrich J, Scienza KM, de Oliveira Alvares L, Quillfeldt JA. Hippocampal plasticity mechanisms mediating experience-dependent learning change over time. Neurobiol Learn Mem 2018; 150:56-63. [PMID: 29501525 DOI: 10.1016/j.nlm.2018.02.020] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2017] [Revised: 01/02/2018] [Accepted: 02/19/2018] [Indexed: 01/15/2023]
Abstract
The requirement of NMDA receptor (NMDAR) activity for memory formation is well described. However, the plasticity mechanisms for memory can be modified by experience, such that a future similar learning becomes independent of NMDARs. This effect has often been reported in learning events conducted with a few days interval. In this work, we asked whether the NMDAR-independency is permanent or the brain regions and plasticity mechanisms of experience-dependent learning may change over time. Considering that contextual memories undergo a gradual reorganization over time, becoming progressively independent from the hippocampus and dependent upon cortical regions, we investigated the brain regions mediating a new related learning conducted at a remote time-point, when the first memory was already cortically established. First, we demonstrated that anterior cingulate cortex was not able to support a learning subsequent to a previous systems-level consolidated memory; it did require at least one functional subregion of the hippocampus (ventral or dorsal). Moreover, after replicating findings showing that a few days interval between trainings induces a NMDAR-independent learning, we managed to show that a learning following a longer interval once again becomes dependent on NMDARs in the hippocampus. These findings suggest that while the previous memory grows independent from the hippocampus over time, an experience-dependent learning following a systems-consolidated memory once again engages the hippocampus and a NMDAR-dependent plasticity mechanism.
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Affiliation(s)
- Ana Paula Crestani
- Psychobiology and Neurocomputation Lab, Biophysics Department, Bioscience Institute, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Neurosciences Graduate Program, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Rodrigo Ordoñez Sierra
- Psychobiology and Neurocomputation Lab, Biophysics Department, Bioscience Institute, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Neurosciences Graduate Program, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Adriano Machado
- Psychobiology and Neurocomputation Lab, Biophysics Department, Bioscience Institute, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Neurosciences Graduate Program, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Josué Haubrich
- Psychobiology and Neurocomputation Lab, Biophysics Department, Bioscience Institute, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Neurosciences Graduate Program, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Krislei Martin Scienza
- Psychobiology and Neurocomputation Lab, Biophysics Department, Bioscience Institute, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Neurosciences Graduate Program, Federal University of Rio Grande do Sul, Porto Alegre, Brazil
| | - Lucas de Oliveira Alvares
- Neurosciences Graduate Program, Federal University of Rio Grande do Sul, Porto Alegre, Brazil; Neurobiology of Memory Lab, Biophysics Department, Bioscience Institute, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
| | - Jorge Alberto Quillfeldt
- Psychobiology and Neurocomputation Lab, Biophysics Department, Bioscience Institute, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil; Neurosciences Graduate Program, Federal University of Rio Grande do Sul, Porto Alegre, Brazil.
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Integrating Spatial Working Memory and Remote Memory: Interactions between the Medial Prefrontal Cortex and Hippocampus. Brain Sci 2017; 7:brainsci7040043. [PMID: 28420200 PMCID: PMC5406700 DOI: 10.3390/brainsci7040043] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Revised: 04/11/2017] [Accepted: 04/14/2017] [Indexed: 12/22/2022] Open
Abstract
In recent years, two separate research streams have focused on information sharing between the medial prefrontal cortex (mPFC) and hippocampus (HC). Research into spatial working memory has shown that successful execution of many types of behaviors requires synchronous activity in the theta range between the mPFC and HC, whereas studies of memory consolidation have shown that shifts in area dependency may be temporally modulated. While the nature of information that is being communicated is still unclear, spatial working memory and remote memory recall is reliant on interactions between these two areas. This review will present recent evidence that shows that these two processes are not as separate as they first appeared. We will also present a novel conceptualization of the nature of the medial prefrontal representation and how this might help explain this area’s role in spatial working memory and remote memory recall.
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Prelimbic cortex extracellular signal-regulated kinase 1/2 activation is required for memory retrieval of long-term inhibitory avoidance. Brain Res 2017; 1661:88-99. [DOI: 10.1016/j.brainres.2017.02.010] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2016] [Revised: 02/06/2017] [Accepted: 02/08/2017] [Indexed: 11/22/2022]
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Pedraza LK, Sierra RO, Crestani AP, Quillfeldt JA, de Oliveira Alvares L. Sequential learning during contextual fear conditioning guides the rate of systems consolidation: Implications for consolidation of multiple memory traces. Hippocampus 2017; 27:518-528. [DOI: 10.1002/hipo.22708] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2016] [Revised: 01/05/2017] [Accepted: 01/12/2017] [Indexed: 11/10/2022]
Affiliation(s)
- Lizeth K. Pedraza
- Laboratório de Neurobiologia da Memória; Biophysics Department, Biosciences Institute, Universidade Federal do Rio Grande do Sul; Porto Alegre RS, Brazil
- Institute of Health Sciences, Graduate Program in Neuroscience; Universidade Federal do Rio Grande do Sul; Porto Alegre RS, Brazil
| | - Rodrigo O. Sierra
- Institute of Health Sciences, Graduate Program in Neuroscience; Universidade Federal do Rio Grande do Sul; Porto Alegre RS, Brazil
- Laboratório de Psicobiologia e Neurocomputação, Biophysics Department; Biosciences Institute, Universidade Federal do Rio Grande do Sul; Porto Alegre Brazil
| | - Ana P. Crestani
- Institute of Health Sciences, Graduate Program in Neuroscience; Universidade Federal do Rio Grande do Sul; Porto Alegre RS, Brazil
- Laboratório de Psicobiologia e Neurocomputação, Biophysics Department; Biosciences Institute, Universidade Federal do Rio Grande do Sul; Porto Alegre Brazil
| | - Jorge A. Quillfeldt
- Institute of Health Sciences, Graduate Program in Neuroscience; Universidade Federal do Rio Grande do Sul; Porto Alegre RS, Brazil
- Laboratório de Psicobiologia e Neurocomputação, Biophysics Department; Biosciences Institute, Universidade Federal do Rio Grande do Sul; Porto Alegre Brazil
| | - Lucas de Oliveira Alvares
- Laboratório de Neurobiologia da Memória; Biophysics Department, Biosciences Institute, Universidade Federal do Rio Grande do Sul; Porto Alegre RS, Brazil
- Institute of Health Sciences, Graduate Program in Neuroscience; Universidade Federal do Rio Grande do Sul; Porto Alegre RS, Brazil
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Increased task demand during spatial memory testing recruits the anterior cingulate cortex. Learn Mem 2016; 23:450-4. [PMID: 27531834 PMCID: PMC4986854 DOI: 10.1101/lm.042366.116] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2016] [Accepted: 06/07/2016] [Indexed: 11/25/2022]
Abstract
We examined whether increasing retrieval difficulty in a spatial memory task would promote the recruitment of the anterior cingulate cortex (ACC) similar to what is typically observed during remote memory retrieval. Rats were trained on the hidden platform version of the Morris Water Task and tested three or 30 d later. Retrieval difficulty was manipulated by removing several prominent extra-pool cues from the testing room. Immediate early gene expression (c-Fos) in the ACC was greater following the cue removal and comparable to remote memory retrieval (30-d retention interval) levels, supporting the view of increased ACC contribution during high cognitive-demand memory processes.
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Jasnow AM, Lynch JF, Gilman TL, Riccio DC. Perspectives on fear generalization and its implications for emotional disorders. J Neurosci Res 2016; 95:821-835. [PMID: 27448175 DOI: 10.1002/jnr.23837] [Citation(s) in RCA: 62] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2015] [Revised: 06/22/2016] [Accepted: 06/22/2016] [Indexed: 12/28/2022]
Abstract
Although generalization to conditioned stimuli is not a new phenomenon, renewed interest in understanding its biological underpinning has stemmed from its association with a number of anxiety disorders. Generalization as it relates to fear processing is a temporally dynamic process in which animals, including humans, display fear in response to similar yet distinct cues or contexts as the time between training and testing increases. This Review surveys the literature on contextual fear generalization and its relation to several views of memory, including systems consolidation, forgetting, and transformation hypothesis, which differentially implicate roles of the hippocampus and neocortex in memory consolidation and retrieval. We discuss recent evidence on the neurobiological mechanisms contributing to the increase in fear generalization over time and how generalized responding may be modulated by acquisition, consolidation, and retrieval mechanisms. Whereas clinical perspectives of generalization emphasize a lack of fear inhibition to CS- cues or fear toward intermediate CS cues, the time-dependent nature of generalization and its relation to traditional views on memory consolidation and retrieval are often overlooked. Understanding the time-dependent increase in fear generalization has important implications not only for understanding how generalization contributes to anxiety disorders but also for understanding basic long-term memory function. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Aaron M Jasnow
- Department of Psychological Sciences, Kent State University, Kent, Ohio
| | - Joseph F Lynch
- Department of Psychological Sciences, Kent State University, Kent, Ohio
| | - T Lee Gilman
- Department of Psychological Sciences, Kent State University, Kent, Ohio
| | - David C Riccio
- Department of Psychological Sciences, Kent State University, Kent, Ohio
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Haubrich J, Cassini LF, Diehl F, Santana F, Fürstenau de Oliveira L, de Oliveira Alvares L, Quillfeldt JA. Novel learning accelerates systems consolidation of a contextual fear memory. Hippocampus 2016; 26:924-32. [DOI: 10.1002/hipo.22575] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/04/2016] [Indexed: 11/10/2022]
Affiliation(s)
- Josue Haubrich
- Departamento de Biofísica, Laboratório de Psicobiologia e Neurocomputação, Instituto de Biociências; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
- Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas Da Saúde; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
| | - Lindsey Freitas Cassini
- Departamento de Biofísica, Laboratório de Psicobiologia e Neurocomputação, Instituto de Biociências; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
- Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas Da Saúde; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
| | - Felipe Diehl
- Departamento de Biofísica, Laboratório de Psicobiologia e Neurocomputação, Instituto de Biociências; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
- Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas Da Saúde; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
| | - Fabiana Santana
- Departamento de Biofísica, Laboratório de Psicobiologia e Neurocomputação, Instituto de Biociências; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
- Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas Da Saúde; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
| | - Lucas Fürstenau de Oliveira
- Departamento de Biofísica, Laboratório de Psicobiologia e Neurocomputação, Instituto de Biociências; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
- Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas Da Saúde; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
| | - Lucas de Oliveira Alvares
- Departamento de Biofísica, Laboratório de Psicobiologia e Neurocomputação, Instituto de Biociências; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
- Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas Da Saúde; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
- Departamento de Biofísica, Laboratório de Neurobiologia da Memória, Instituto de Biociências; Universidade Federal Do Rio Grande do Sul-Porto Alegre; RS Brazil
| | - Jorge Alberto Quillfeldt
- Departamento de Biofísica, Laboratório de Psicobiologia e Neurocomputação, Instituto de Biociências; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
- Programa de Pós-Graduação em Neurociências, Instituto de Ciências Básicas Da Saúde; Universidade Federal do Rio Grande do Sul-Porto Alegre; RS Brazil
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Dissociation of the Role of Infralimbic Cortex in Learning and Consolidation of Extinction of Recent and Remote Aversion Memory. Neuropsychopharmacology 2015; 40:2566-75. [PMID: 25872918 PMCID: PMC4569946 DOI: 10.1038/npp.2015.103] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2014] [Revised: 03/18/2015] [Accepted: 03/29/2015] [Indexed: 01/04/2023]
Abstract
Medial prefrontal circuits have been reported to undergo a major reorganization over time and gradually take a more important role for remote emotional memories such as contextual fear memory or food aversion memory. The medial prefrontal cortex, and specifically its ventral subregion, the infralimbic cortex (IL), was also reported to be critical for recent memory extinction of contextual fear conditioning and conditioned odor aversion. However, its exact role in the extinction of remotely acquired information is still not clear. Using postretrieval blockade of protein synthesis or inactivation of the IL, we showed that the IL is similarly required for extinction consolidation of recent and remote fear memory. However, in odor aversion memory, the IL was only involved in extinction consolidation of recent, but not remote, memory. In contrast, only remote retrieval of aversion memory induced c-Fos activation in the IL and preretrieval inactivation of the IL with lidocaine impaired subsequent extinction of remote but not recent memory, indicating IL is necessary for extinction learning of remote aversion memory. In contrast to the effects in odor aversion, our data show that the involvement of the IL in the consolidation of fear extinction does not depend on the memory age. More importantly, our data indicate that the IL is implicated in the extinction of fear and nonfear-based associations and suggest dissociation in the engagement of the IL in the learning and consolidation of food aversion extinction over time.
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Fitzgerald PJ, Pinard CR, Camp MC, Feyder M, Sah A, Bergstrom H, Graybeal C, Liu Y, Schlüter O, Grant SG, Singewald N, Xu W, Holmes A. Durable fear memories require PSD-95. Mol Psychiatry 2015; 20:901-12. [PMID: 25510511 PMCID: PMC4469631 DOI: 10.1038/mp.2014.161] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/04/2014] [Revised: 07/28/2014] [Accepted: 10/15/2014] [Indexed: 12/13/2022]
Abstract
Traumatic fear memories are highly durable but also dynamic, undergoing repeated reactivation and rehearsal over time. Although overly persistent fear memories underlie anxiety disorders, such as posttraumatic stress disorder, the key neural and molecular mechanisms underlying fear memory durability remain unclear. Postsynaptic density 95 (PSD-95) is a synaptic protein regulating glutamate receptor anchoring, synaptic stability and certain types of memory. Using a loss-of-function mutant mouse lacking the guanylate kinase domain of PSD-95 (PSD-95(GK)), we analyzed the contribution of PSD-95 to fear memory formation and retrieval, and sought to identify the neural basis of PSD-95-mediated memory maintenance using ex vivo immediate-early gene mapping, in vivo neuronal recordings and viral-mediated knockdown (KD) approaches. We show that PSD-95 is dispensable for the formation and expression of recent fear memories, but essential for the formation of precise and flexible fear memories and for the maintenance of memories at remote time points. The failure of PSD-95(GK) mice to retrieve remote cued fear memory was associated with hypoactivation of the infralimbic (IL) cortex (but not the anterior cingulate cortex (ACC) or prelimbic cortex), reduced IL single-unit firing and bursting, and attenuated IL gamma and theta oscillations. Adeno-associated virus-mediated PSD-95 KD in the IL, but not the ACC, was sufficient to impair recent fear extinction and remote fear memory, and remodel IL dendritic spines. Collectively, these data identify PSD-95 in the IL as a critical mechanism supporting the durability of fear memories over time. These preclinical findings have implications for developing novel approaches to treating trauma-based anxiety disorders that target the weakening of overly persistent fear memories.
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Affiliation(s)
- Paul J. Fitzgerald
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, NIH
| | - Courtney R. Pinard
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, NIH
| | - Marguerite C. Camp
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, NIH
| | - Michael Feyder
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, NIH
| | - Anupam Sah
- Department of Pharmacology & Toxicology, University of Innsbruck, Innsbruck, Austria
| | - Hadley Bergstrom
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, NIH
| | - Carolyn Graybeal
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, NIH
| | - Yan Liu
- Department of Brain and Cognitive Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | | | - Seth G.N. Grant
- Centre for Clinical Brain Sciences and Centre for Neuroregeneration, The University of Edinburgh, Edinburgh, UK
| | - Nicolas Singewald
- Department of Pharmacology & Toxicology, University of Innsbruck, Innsbruck, Austria
| | - Weifeng Xu
- Department of Brain and Cognitive Science, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Andrew Holmes
- Laboratory of Behavioral and Genomic Neuroscience, National Institute on Alcohol Abuse and Alcoholism, Bethesda, MD, NIH
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Differential contribution of hippocampal subfields to components of associative taste learning. J Neurosci 2014; 34:11007-15. [PMID: 25122900 DOI: 10.1523/jneurosci.0956-14.2014] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023] Open
Abstract
The ability to associate the consumption of a taste with its positive or negative consequences is fundamental to survival and influences the behavior of species ranging from invertebrate to human. As a result, for both research and clinical reasons, there has been a great effort to understand the neuronal circuits, as well as the cellular and molecular mechanisms, underlying taste learning. From a neuroanatomical perspective, the contributions of the cortex and amygdala are well documented; however, the literature is riddled with conflicting results regarding the role of the hippocampus in different facets of taste learning. Here, we use conditional genetics in mice to block NMDA receptor-dependent plasticity individually in each of the three major hippocampal subfields, CA1, CA3, and the dentate gyrus, via deletion of the NR1 subunit. Across the CA1, CA3, and dentate gyrus NR1 knock-out lines, we uncover a pattern of differential deficits that establish the dispensability of hippocampal plasticity in incidental taste learning, the requirement of CA1 plasticity for associative taste learning, and a specific requirement for plasticity in the dentate gyrus when there is a long temporal gap between the taste and its outcome. Together, these data establish that the hippocampus is involved in associative taste learning and suggest an episodic component to this type of memory.
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Inactivation of the anterior cingulate reveals enhanced reliance on cortical networks for remote spatial memory retrieval after sequential memory processing. PLoS One 2014; 9:e108711. [PMID: 25279556 PMCID: PMC4184828 DOI: 10.1371/journal.pone.0108711] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2014] [Accepted: 09/01/2014] [Indexed: 01/09/2023] Open
Abstract
One system consolidation model suggests that as time passes, ensembles of cortical neurons form strong connections to represent remote memories. In this model, the anterior cingulate cortex (ACC) serves as a cortical region that represents remote memories. However, there is debate as to whether remote spatial memories go through this systems consolidation process and come to rely on the ACC. The present experiment examined whether increasing the processing demand on the hippocampus, by sequential training on two spatial tasks, would more fully engage the ACC during retrieval of a remote spatial memory. In this scenario, inactivation of the ACC at a remote time point was hypothesized to produce a severe memory deficit if rats had been trained on two, sequential spatial tasks. Rats were trained on a water maze (WM) task only or a WM task followed by a radial arm maze task. A WM probe test was given recently or remotely to all rats. Prior to the probe test, rats received an injection of saline or muscimol into the ACC. A subtle deficit in probe performance was found at the remote time point in the group trained on only one spatial task and treated with muscimol. In the group trained on two spatial tasks and treated with muscimol, a subtle deficit in probe performance was noted at the recent time point and a substantial deficit in probe performance was observed at the remote time point. c-Fos labeling in the hippocampus revealed more labeling in the CA1 region in all remotely tested groups than recently tested groups. Findings suggest that spatial remote memories come to rely more fully on the ACC when hippocampal processing requirements are increased. Results also suggest continued involvement of the hippocampus in spatial memory retrieval along with a progressive strengthening of cortical connections as time progresses.
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Cholvin T, Loureiro M, Cassel R, Cosquer B, Herbeaux K, de Vasconcelos AP, Cassel JC. Dorsal hippocampus and medial prefrontal cortex each contribute to the retrieval of a recent spatial memory in rats. Brain Struct Funct 2014; 221:91-102. [PMID: 25260556 DOI: 10.1007/s00429-014-0894-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2014] [Accepted: 09/19/2014] [Indexed: 01/25/2023]
Abstract
Systems-level consolidation models propose that recent memories are initially hippocampus-dependent. When remote, they are partially or completely dependent upon the medial prefrontal cortex (mPFC). An implication of the mPFC in recent memory, however, is still debated. Different amounts of muscimol (MSCI 0, 30, 50, 80 and 250 ng in 1 µL PBS) were used to assess the impact of inactivation of the dorsal hippocampus (dHip) or the mPFC (targeting the prelimbic cortex) on a 24-h delayed retrieval of a platform location that rats had learned drug-free in a water maze. The two smallest amounts of MSCI (30 and 50 ng) did not affect recall, whatever the region. 80 ng MSCI infused into the dHip disrupted spatial memory retrieval, as did the larger amount. Infusion of MSCI into the mPFC did not alter performance in the 0-80 ng range. At 250 ng, it induced an as dramatic memory impairment as after efficient dHip inactivation. Stereological quantifications showed that 80 ng MSCI in the dHip and 250 ng MSCI in the mPFC induced a more than 80% reduction of c-Fos expression, suggesting that, beyond the amounts infused, it is the magnitude of the neuronal activity decrease which is determinant as to the functional outcome of the inactivation. Because, based on the literature, even 250 ng MSCI is a small amount, our results point to a contribution of the mPFC to the recall of a recently acquired spatial memory and thereby extend our knowledge about the functions of this major actor of cognition.
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Affiliation(s)
- Thibault Cholvin
- Laboratoire de Neurosciences Cognitives et Adaptatives, UMR 7364, CNRS, Université de Strasbourg, Neuropôle de Strasbourg, GDR 2905 du CNRS, Faculté de Psychologie, 12 rue Goethe, 67000, Strasbourg, France
| | - Michaël Loureiro
- Laboratoire de Neurosciences Cognitives et Adaptatives, UMR 7364, CNRS, Université de Strasbourg, Neuropôle de Strasbourg, GDR 2905 du CNRS, Faculté de Psychologie, 12 rue Goethe, 67000, Strasbourg, France
| | - Raphaelle Cassel
- Laboratoire de Neurosciences Cognitives et Adaptatives, UMR 7364, CNRS, Université de Strasbourg, Neuropôle de Strasbourg, GDR 2905 du CNRS, Faculté de Psychologie, 12 rue Goethe, 67000, Strasbourg, France
| | - Brigitte Cosquer
- Laboratoire de Neurosciences Cognitives et Adaptatives, UMR 7364, CNRS, Université de Strasbourg, Neuropôle de Strasbourg, GDR 2905 du CNRS, Faculté de Psychologie, 12 rue Goethe, 67000, Strasbourg, France
| | - Karin Herbeaux
- Laboratoire de Neurosciences Cognitives et Adaptatives, UMR 7364, CNRS, Université de Strasbourg, Neuropôle de Strasbourg, GDR 2905 du CNRS, Faculté de Psychologie, 12 rue Goethe, 67000, Strasbourg, France
| | - Anne Pereira de Vasconcelos
- Laboratoire de Neurosciences Cognitives et Adaptatives, UMR 7364, CNRS, Université de Strasbourg, Neuropôle de Strasbourg, GDR 2905 du CNRS, Faculté de Psychologie, 12 rue Goethe, 67000, Strasbourg, France.
| | - Jean-Christophe Cassel
- Laboratoire de Neurosciences Cognitives et Adaptatives, UMR 7364, CNRS, Université de Strasbourg, Neuropôle de Strasbourg, GDR 2905 du CNRS, Faculté de Psychologie, 12 rue Goethe, 67000, Strasbourg, France
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Wartman BC, Holahan MR. The impact of multiple memory formation on dendritic complexity in the hippocampus and anterior cingulate cortex assessed at recent and remote time points. Front Behav Neurosci 2014; 8:128. [PMID: 24795581 PMCID: PMC4001003 DOI: 10.3389/fnbeh.2014.00128] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Accepted: 03/27/2014] [Indexed: 01/29/2023] Open
Abstract
Consolidation processes, involving synaptic and systems level changes, are suggested to stabilize memories once they are formed. At the synaptic level, dendritic structural changes are associated with long-term memory storage. At the systems level, memory storage dynamics between the hippocampus and anterior cingulate cortex (ACC) may be influenced by the number of sequentially encoded memories. The present experiment utilized Golgi-Cox staining and neuron reconstruction to examine recent and remote structural changes in the hippocampus and ACC following training on three different behavioral procedures. Rats were trained on one hippocampal-dependent task only (a water maze task), two hippocampal-dependent tasks (a water maze task followed by a radial arm maze task), or one hippocampal-dependent and one non-hippocampal-dependent task (a water maze task followed by an operant conditioning task). Rats were euthanized recently or remotely. Brains underwent Golgi-Cox processing and neurons were reconstructed using Neurolucida software (MicroBrightField, Williston, VT, USA). Rats trained on two hippocampal-dependent tasks displayed increased dendritic complexity compared to control rats, in neurons examined in both the ACC and hippocampus at recent and remote time points. Importantly, this behavioral group showed consistent, significant structural differences in the ACC compared to the control group at the recent time point. These findings suggest that taxing the demand placed upon the hippocampus, by training rats on two hippocampal-dependent tasks, engages synaptic and systems consolidation processes in the ACC at an accelerated rate for recent and remote storage of spatial memories.
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Wartman BC, Holahan MR. The use of sequential hippocampal-dependent and -non-dependent tasks to study the activation profile of the anterior cingulate cortex during recent and remote memory tests. Neurobiol Learn Mem 2013; 106:334-42. [DOI: 10.1016/j.nlm.2013.08.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2012] [Revised: 08/08/2013] [Accepted: 08/20/2013] [Indexed: 10/26/2022]
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Euston DR, Gruber AJ, McNaughton BL. The role of medial prefrontal cortex in memory and decision making. Neuron 2013; 76:1057-70. [PMID: 23259943 DOI: 10.1016/j.neuron.2012.12.002] [Citation(s) in RCA: 912] [Impact Index Per Article: 82.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Some have claimed that the medial prefrontal cortex (mPFC) mediates decision making. Others suggest mPFC is selectively involved in the retrieval of remote long-term memory. Yet others suggests mPFC supports memory and consolidation on time scales ranging from seconds to days. How can all these roles be reconciled? We propose that the function of the mPFC is to learn associations between context, locations, events, and corresponding adaptive responses, particularly emotional responses. Thus, the ubiquitous involvement of mPFC in both memory and decision making may be due to the fact that almost all such tasks entail the ability to recall the best action or emotional response to specific events in a particular place and time. An interaction between multiple memory systems may explain the changing importance of mPFC to different types of memories over time. In particular, mPFC likely relies on the hippocampus to support rapid learning and memory consolidation.
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Affiliation(s)
- David R Euston
- Department of Neuroscience, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada.
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28
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Weible AP. Remembering to attend: the anterior cingulate cortex and remote memory. Behav Brain Res 2013; 245:63-75. [PMID: 23453992 DOI: 10.1016/j.bbr.2013.02.010] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2012] [Revised: 02/08/2013] [Accepted: 02/10/2013] [Indexed: 11/26/2022]
Abstract
Damage to the hippocampus, as first demonstrated with patient HM, results in a profound anterograde and temporally-graded retrograde amnesia. The observation that older memories could still be consciously recollected led to the proposal that, over time, information initially processed in the hippocampus is stored in a distributed cortical network. The anterior cingulate cortex (ACC) has recently been implicated in this process. Studies in rodents have demonstrated that the ACC is necessary for recalling behaviors learned a month or more in the past, but not for the same behaviors learned the previous day. Precisely how the ACC contributes to the recall of remote memories is unknown. Is this role distinct from myriad others proposed for the ACC, or has the approach taken in these studies of assessing function at different points after learning provided a new window through which to view established processes? The present review seeks to address this question. First, the data will be presented implicating the ACC in recall of remote memory. This will be followed by a discussion of studies describing two other primary roles of the ACC, mediating attention and premotor planning, with an emphasis on data collected in rodents, as these will be most directly comparable to the memory studies presented. The available evidence supports a connection among these roles, and suggests a possible synthesis for otherwise seemingly disparate functions reported for the ACC.
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Affiliation(s)
- Aldis P Weible
- Institute of Neuroscience, 212 Lewis Integrative Science Building, University of Oregon, Eugene 97405, OR, USA.
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Zovkic IB, Guzman-Karlsson MC, Sweatt JD. Epigenetic regulation of memory formation and maintenance. Learn Mem 2013; 20:61-74. [PMID: 23322554 DOI: 10.1101/lm.026575.112] [Citation(s) in RCA: 229] [Impact Index Per Article: 20.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Understanding the cellular and molecular mechanisms underlying the formation and maintenance of memories is a central goal of the neuroscience community. It is well regarded that an organism's ability to lastingly adapt its behavior in response to a transient environmental stimulus relies on the central nervous system's capability for structural and functional plasticity. This plasticity is dependent on a well-regulated program of neurotransmitter release, post-synaptic receptor activation, intracellular signaling cascades, gene transcription, and subsequent protein synthesis. In the last decade, epigenetic markers like DNA methylation and post-translational modifications of histone tails have emerged as important regulators of the memory process. Their ability to regulate gene transcription dynamically in response to neuronal activation supports the consolidation of long-term memory. Furthermore, the persistent and self-propagating nature of these mechanisms, particularly DNA methylation, suggests a molecular mechanism for memory maintenance. In this review, we will examine the evidence that supports a role of epigenetic mechanisms in learning and memory. In doing so, we hope to emphasize (1) the widespread involvement of these mechanisms across different behavioral paradigms and distinct brain regions, (2) the temporal and genetic specificity of these mechanisms in response to upstream signaling cascades, and (3) the functional outcome these mechanisms may have on structural and functional plasticity. Finally, we consider the future directions of neuroepigenetic research as it relates to neuronal storage of information.
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Affiliation(s)
- Iva B Zovkic
- Department of Neurobiology and Evelyn F McKnight Brain Institute, University of Alabama at Birmingham, Birmingham, Alabama 35294, USA
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30
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Abstract
One of the most exciting discoveries in the learning and memory field in the past two decades is the observation that active regulation of gene expression is necessary for experience to trigger lasting functional and behavioral change, in a wide variety of species, including humans. Thus, as opposed to the traditional view of 'nature' (genes) being separate from 'nurture' (environment and experience), it is now clear that experience actively drives alterations in central nervous system (CNS) gene expression in an ongoing fashion, and that the resulting transcriptional changes are necessary for experience to trigger altered long-term behavior. In parallel over the past decade, epigenetic mechanisms, including regulation of chromatin structure and DNA methylation, have been shown to be potent regulators of gene transcription in the CNS. In this review, we describe data supporting the hypothesis that epigenetic molecular mechanisms, especially DNA methylation and demethylation, drive long-term behavioral change through active regulation of gene transcription in the CNS. Specifically, we propose that epigenetic molecular mechanisms underlie the formation and stabilization of context- and cue-triggered fear conditioning based in the hippocampus and amygdala, a conclusion reached in a wide variety of studies using laboratory animals. Given the relevance of cued and contextual fear conditioning to post-traumatic stress, by extension we propose that these mechanisms may contribute to post-traumatic stress disorder (PTSD) in humans. Moreover, we speculate that epigenetically based pharmacotherapy may provide a new avenue of drug treatment for PTSD-related cognitive and behavioral function.
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Affiliation(s)
- Iva B Zovkic
- Department of Neurobiology, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, AL, USA
| | - J David Sweatt
- Department of Neurobiology, Evelyn F. McKnight Brain Institute, University of Alabama, Birmingham, AL, USA,Department of Neurobiology, Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham, 1010 Shelby Building, 1825 University Boulevard, Birmingham, AL 35294-2182, USA, Tel: +205 975 5196, Fax: +205 934 6571, E-mail:
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31
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Zovkic IB, Meadows JP, Kaas GA, Sweatt JD. Interindividual Variability in Stress Susceptibility: A Role for Epigenetic Mechanisms in PTSD. Front Psychiatry 2013; 4:60. [PMID: 23805109 PMCID: PMC3693073 DOI: 10.3389/fpsyt.2013.00060] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2013] [Accepted: 06/11/2013] [Indexed: 12/13/2022] Open
Abstract
Post-traumatic stress disorder (PTSD) is a psychiatric condition characterized by intrusive and persistent memories of a psychologically traumatic event that leads to significant functional and social impairment in affected individuals. The molecular bases underlying persistent outcomes of a transient traumatic event have remained elusive for many years, but recent studies in rodents have implicated epigenetic modifications of chromatin structure and DNA methylation as fundamental mechanisms for the induction and stabilization of fear memory. In addition to mediating adaptations to traumatic events that ultimately cause PTSD, epigenetic mechanisms are also involved in establishing individual differences in PTSD risk and resilience by mediating long-lasting effects of genes and early environment on adult function and behavior. In this review, we discuss the current evidence for epigenetic regulation of PTSD in human studies and in animal models and comment on ways in which these models can be expanded. In addition, we identify key outstanding questions in the study of epigenetic mechanisms of PTSD in the context of rapidly evolving technologies that are constantly updating and adjusting our understanding of epigenetic modifications and their functional roles. Finally, we discuss the potential application of epigenetic approaches in identifying markers of risk and resilience that can be utilized to promote early intervention and develop therapeutic strategies to combat PTSD after symptom onset.
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Affiliation(s)
- Iva B Zovkic
- Department of Neurobiology, Evelyn F. McKnight Brain Institute, University of Alabama at Birmingham , Birmingham, AL , USA
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32
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Euston DR, Gruber AJ, McNaughton BL. The role of medial prefrontal cortex in memory and decision making. Neuron 2012. [PMID: 23259943 DOI: 10.1016/j.neuron.2012.12.002.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/30/2022]
Abstract
Some have claimed that the medial prefrontal cortex (mPFC) mediates decision making. Others suggest mPFC is selectively involved in the retrieval of remote long-term memory. Yet others suggests mPFC supports memory and consolidation on time scales ranging from seconds to days. How can all these roles be reconciled? We propose that the function of the mPFC is to learn associations between context, locations, events, and corresponding adaptive responses, particularly emotional responses. Thus, the ubiquitous involvement of mPFC in both memory and decision making may be due to the fact that almost all such tasks entail the ability to recall the best action or emotional response to specific events in a particular place and time. An interaction between multiple memory systems may explain the changing importance of mPFC to different types of memories over time. In particular, mPFC likely relies on the hippocampus to support rapid learning and memory consolidation.
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Affiliation(s)
- David R Euston
- Department of Neuroscience, University of Lethbridge, Lethbridge, AB T1K 3M4, Canada.
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33
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Abstract
Damage to the hippocampal formation results in a profound temporally graded retrograde amnesia, implying that it is necessary for memory acquisition but not its long-term storage. It is therefore thought that memories are transferred from the hippocampus to the cortex for long-term storage in a process called systems consolidation (Dudai and Morris, 2000). Where in the cortex this occurs remains an open question. Recent work (Frankland et al., 2005; Vetere et al., 2011) suggests the anterior cingulate cortex (ACC) as a likely candidate area, but there is little direct electrophysiological evidence to support this claim. Previously, we demonstrated object-associated firing correlates in caudal ACC during tests of recognition memory and described evidence of neuronal responses to where an object had been following a brief delay. However, long-term memory requires evidence of more durable representations. Here we examined the activity of ACC neurons while testing for long-term memory of an absent object. Mice explored two objects in an arena and then were returned 6 h later with one of the objects removed. Mice continued to explore where the object had been, demonstrating memory for that object. Remarkably, some ACC neurons continued to respond where the object had been, while others developed new responses in the absent object's location. The incidence of absent-object responses by ACC neurons was greatly increased with increased familiarization to the objects, and such responses were still evident 1 month later. These data strongly suggest that the ACC contains neural correlates of consolidated object/place association memory.
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Predicting aversive events and terminating fear in the mouse anterior cingulate cortex during trace fear conditioning. J Neurosci 2012; 32:1082-95. [PMID: 22262906 DOI: 10.1523/jneurosci.5566-11.2012] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
A variety of studies have implicated the anterior cingulate cortex (ACC) in fear, including permanent storage of fear memory. Recent pharmacological and genetic studies indicate that early synaptic plasticity in the ACC may also contribute to certain forms of fear memory at early time points. However, no study has directly examined the possible changes in neuronal activity of ACC neurons in freely behaving mice during early learning. In the present study, we examined the neural responses of the ACC during trace fear conditioning. We found that ACC putative pyramidal and nonpyramidal neurons were involved in the termination of fear behavior ("un-freezing"), and the spike activity of these neurons was reduced during freezing. Some of the neurons were also found to acquire un-freezing locked activity and change their tuning. The results implicate the ACC neurons in fear learning and controlling the abolition of fear behavior. We also show that the ACC is important for making cue-related fear memory associations in the trace fear paradigm as measured with tone-evoked potentials and single-unit activity. Collectively, our findings indicate that the ACC is involved in predicting future aversive events and terminating fear during trace fear.
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Lucas M, Frenois F, Cador M, Le Moine C. Remodeling of the neuronal circuits underlying opiate-withdrawal memories following remote retrieval. Neurobiol Learn Mem 2012; 97:47-53. [DOI: 10.1016/j.nlm.2011.09.002] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 08/26/2011] [Accepted: 09/07/2011] [Indexed: 10/17/2022]
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36
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Abstract
New neurons are continuously generated in the subgranular zone of the adult hippocampus and, once sufficiently mature, are thought to integrate into hippocampal memory circuits. However, whether they play an essential role in subsequent memory expression is not known. Previous studies have shown that suppression of adult neurogenesis often (but not always) impairs subsequent hippocampus-dependent learning (i.e., produces anterograde effects). A major challenge for these studies is that these new neurons represent only a small subpopulation of all dentate granule cells, and so there is large potential for either partial or complete compensation by granule cells generated earlier on during development. A potentially more powerful approach to investigate this question would be to ablate adult-generated neurons after they have already become part of a memory trace (i.e., retrograde effects). Here we developed a diphtheria toxin-based strategy in mice that allowed us to selectively ablate a population of predominantly mature, adult-generated neurons either before or after learning, without affecting ongoing neurogenesis. Removal of these neurons before learning did not prevent the formation of new contextual fear or water maze memories. In contrast, removal of an equivalent population after learning degraded existing contextual fear and water maze memories, without affecting nonhippocampal memory. Ablation of these adult-generated neurons even 1 month after learning produced equivalent memory degradation in the water maze. These retrograde effects suggest that adult-generated neurons form a critical and enduring component of hippocampal memory traces.
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37
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Recent and remote spatial memory in mice treated with cytosine arabinoside. Pharmacol Biochem Behav 2011; 100:451-7. [PMID: 22020055 DOI: 10.1016/j.pbb.2011.10.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/27/2011] [Revised: 09/16/2011] [Accepted: 10/06/2011] [Indexed: 11/21/2022]
Abstract
Clinical studies suggest that chemotherapy is associated with long-term cognitive impairment in some patients. A number of underlying mechanisms have been proposed, however, the etiology of chemotherapy-related cognitive dysfunction remains relatively unknown. As part of a multifaceted approach, animal models of chemotherapy-induced cognitive impairment are being developed. Thus far, the majority of animal studies have utilized a rat model, however, mice may prove particularly beneficial in studying genetic risk factors for developing chemotherapy-induced cognitive impairment. Various chemotherapy agents, including cytosine arabinoside (Ara-C), have been found to impair remote spatial memory in rats in the Morris water maze. The present study evaluated the effects of Ara-C on remote (30 d) spatial memory in mice. In addition, the possibility that time relative to chemotherapy treatment may modulate the effect of chemotherapy on spatial learning and/or recent (1 d) memory was explored. Male C57BL/6J mice received either Ara-C (275 mg/kg i.p. daily for 5 days) or saline. Spatial learning and memory was assessed using the Morris water maze. Half the mice performed a remote (30 d) memory version of the task and the other half performed a recent (1 d) memory version of the task. The experiment was designed such that the probe trial for the recent memory version occurred on the same day relative to chemotherapy treatment as the remote memory version. Despite significant toxic effects as assessed by weight loss, Ara-C treated mice performed as well as control mice during acquisition, recent memory, and remote memory portions of the task. As are some humans, C57BL/6J mice may be resistant to at least some aspects of chemotherapy induced cognitive decline.
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38
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Yang CP, Gilley JA, Zhang G, Kernie SG. ApoE is required for maintenance of the dentate gyrus neural progenitor pool. Development 2011; 138:4351-62. [PMID: 21880781 DOI: 10.1242/dev.065540] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Many genes regulating adult neurogenesis have been identified and are known to play similar roles during early neuronal development. We recently identified apolipoprotein E (ApoE) as a gene the expression of which is essentially absent in early brain progenitors but becomes markedly upregulated in adult dentate gyrus stem/progenitor cells. Here, we demonstrate that ApoE deficiency impairs adult dentate gyrus development by affecting the neural progenitor pool over time. We utilized ApoE-deficient mice crossed to a nestin-GFP reporter to demonstrate that dentate gyrus progenitor cells proliferate more rapidly at early ages, which is subsequently accompanied by an overall decrease in neural progenitor cell number at later time points. This appears to be secondary to over-proliferation early in life and ultimate depletion of the Type 1 nestin- and GFAP-expressing neural stem cells. We also rescue the proliferation phenotype with an ApoE-expressing retrovirus, demonstrating that ApoE works directly in this regard. These data provide novel insight into late hippocampal development and suggest a possible role for ApoE in neurodegenerative diseases.
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Affiliation(s)
- Cui-Ping Yang
- Department of Pediatrics, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd, Dallas, TX 75390, USA
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39
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Spine growth in the anterior cingulate cortex is necessary for the consolidation of contextual fear memory. Proc Natl Acad Sci U S A 2011; 108:8456-60. [PMID: 21531906 DOI: 10.1073/pnas.1016275108] [Citation(s) in RCA: 134] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Remodeling of cortical connectivity is thought to allow initially hippocampus-dependent memories to be expressed independently of the hippocampus at remote time points. Consistent with this, consolidation of a contextual fear memory is associated with dendritic spine growth in neurons of the anterior cingulate cortex (aCC). To directly test whether such cortical structural remodeling is necessary for memory consolidation, we disrupted spine growth in the aCC at different times following contextual fear conditioning in mice. We took advantage of previous studies showing that the transcription factor myocyte enhancer factor 2 (MEF2) negatively regulates spinogenesis both in vitro and in vivo. We found that increasing MEF2-dependent transcription in the aCC during a critical posttraining window (but not at later time points) blocked both the consolidation-associated dendritic spine growth and subsequent memory expression. Together, these data strengthen the causal link between cortical structural remodeling and memory consolidation and, further, identify MEF2 as a key regulator of these processes.
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40
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Holloway CM, McIntyre CK. Post-training disruption of Arc protein expression in the anterior cingulate cortex impairs long-term memory for inhibitory avoidance training. Neurobiol Learn Mem 2011; 95:425-32. [PMID: 21315825 DOI: 10.1016/j.nlm.2011.02.002] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Revised: 01/24/2011] [Accepted: 02/02/2011] [Indexed: 12/28/2022]
Abstract
The activity-regulated-cytoskeletal-associated protein (Arc) has a well established role in memory consolidation and synaptic plasticity in the hippocampus and amygdala. However the role of Arc within the anterior cingulate cortex (ACC), an area of the brain involved in processing memory for pain, has yet to be examined. Here we sought to determine if Arc protein within neurons of the rat ACC is necessary for the consolidation of a single-trial, contextual inhibitory avoidance (IA) task. Immunohistochemistry and western blotting revealed an increase in Arc protein within the ACC following IA training in a shock-specific manner, suggesting that ACC Arc expression may play a critical role in the consolidation of the aversive task. To directly test this hypothesis, male Sprague-Dawley rats were trained on the IA task and given post-training intra-ACC infusions of Arc antisense oligodeoxynucleotides (ODNs), designed to suppress Arc translation, or control scrambled ODNs that do not suppress Arc translation. Memory retention was tested 48h after training. Arc antisense-induced disruption of Arc protein expression in the ACC impaired long-term memory for the IA task as compared to rats given intra-ACC infusions of the scrambled control ODNS, suggesting that Arc expression in the ACC is important for the consolidation of emotional memory. Results further indicate that knock down of Arc 6h after training impairs IA memory. This is consistent with time course findings indicating elevated Arc expression at 3 and 6h after IA training but not 12 or 48h. Taken together, these findings support the hypothesis that Arc expression in the ACC participates in synaptic plasticity that underlies long-term memory.
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Affiliation(s)
- Crystal M Holloway
- The University of Texas at Dallas, School of Behavioral and Brain Sciences, 800 West Campbell Road, Richardson, TX 75080-3021, USA.
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41
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Learning and memory consolidation: linking molecular and behavioral data. Neuroscience 2011; 176:12-9. [PMID: 21215299 DOI: 10.1016/j.neuroscience.2010.12.056] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Revised: 12/23/2010] [Accepted: 12/28/2010] [Indexed: 12/21/2022]
Abstract
This paper puts together and links some classic and recent molecular data and hypothesis from different authors and laboratories related to learning and memory consolidation. Mainly addressed to non-specialists, it describes how the glutamatergic activation of plastic synapses in the hippocampus can give rise to new or enlarged dendritic spines which may constitute the main structural basis of some kind of memories. To establish learning and memory, the nervous system can use part of the same mechanisms which make the basic structure of neurons during the ontogenetic development of the brain. Through different families of kinases, phosphatases and other proteins, the activated N-methyl-d-aspartate (NMDA) receptors and different intracellular signals originated in the post-synaptic membranes can promote the synthesis of new proteins and the dynamic of actin. The consecutive morphological changes in the cytoskeleton of the neuron, later stabilized by new receptors inserted in the post-synaptic membranes, make possible memory consolidation. Short and long-term, as well as persistence, of memory mechanisms are related to these molecular processes. Recent research on system consolidation and memory allocation in neural circuits is also explained.
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Gilmartin MR, Helmstetter FJ. Trace and contextual fear conditioning require neural activity and NMDA receptor-dependent transmission in the medial prefrontal cortex. Learn Mem 2010; 17:289-96. [PMID: 20504949 DOI: 10.1101/lm.1597410] [Citation(s) in RCA: 144] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The contribution of the medial prefrontal cortex (mPFC) to the formation of memory is a subject of considerable recent interest. Notably, the mechanisms supporting memory acquisition in this structure are poorly understood. The mPFC has been implicated in the acquisition of trace fear conditioning, a task that requires the association of a conditional stimulus (CS) and an aversive unconditional stimulus (UCS) across a temporal gap. In both rat and human subjects, frontal regions show increased activity during the trace interval separating the CS and UCS. We investigated the contribution of prefrontal neural activity in the rat to the acquisition of trace fear conditioning using microinfusions of the gamma-aminobutyric acid type A (GABA(A)) receptor agonist muscimol. We also investigated the role of prefrontal N-methyl-d-aspartate (NMDA) receptor-mediated signaling in trace fear conditioning using the NMDA receptor antagonist 2-amino-5-phosphonovaleric acid (APV). Temporary inactivation of prefrontal activity with muscimol or blockade of NMDA receptor-dependent transmission in mPFC impaired the acquisition of trace, but not delay, conditional fear responses. Simultaneously acquired contextual fear responses were also impaired in drug-treated rats exposed to trace or delay, but not unpaired, training protocols. Our results support the idea that synaptic plasticity within the mPFC is critical for the long-term storage of memory in trace fear conditioning.
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Affiliation(s)
- Marieke R Gilmartin
- Department of Psychology, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA.
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43
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Inui-Yamamoto C, Yoshioka Y, Inui T, Sasaki KS, Ooi Y, Ueda K, Seiyama A, Ohzawa I. The brain mapping of the retrieval of conditioned taste aversion memory using manganese-enhanced magnetic resonance imaging in rats. Neuroscience 2010; 167:199-204. [PMID: 20167260 DOI: 10.1016/j.neuroscience.2010.02.027] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2009] [Revised: 02/09/2010] [Accepted: 02/11/2010] [Indexed: 10/19/2022]
Abstract
Manganese-enhanced MRI (MEMRI) is a newly developed noninvasive imaging technique of brain activities. The signal intensity of MEMRI reflects cumulative activities of the neurons. To validate the use of MEMRI technique to investigate the neural mechanisms of learning and memory, we tried to map brain areas involved in the retrieval of conditioned taste aversion (CTA) memory. CTAs were established to saccharin (conditioned stimulus: CS) by pairing its ingestion with an i.p. injection of LiCl (unconditioned stimulus: US). LiCl solutions (as a robust aversion chemical) of 0.15 M were injected i.p. 15 min after drinking the saccharine solution (CS). After the two times conditionings, these rats showed a robust aversion to the saccharine solution (CS). Rats of the control group were injected saline i.p. instead of LiCl solutions. The MRI signal intensities at the gustatory cortex (GC), the core subregion of the nucleus accumbens (NAcC), the shell subregion of the nucleus accumbens (NAcSh), the ventral pallidum (VP), the central nucleus of amygdala (CeA), the lateral hypothalamus (LH), and the basolateral nucleus of amygdala (BLA) of the conditioned group were higher than those of the control group. There were no significant differences between the conditioned and the control groups in the intensities for other regions, such as the striatum area, motor cortex, cingulate cortex, interstitial nucleus of the posterior limb of the anterior commissure and hippocampus. These indicate that the GC, NAcC, NAcSh, VP, CeA, LH and BLA have important roles in the memory retrieval of CTA.
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Affiliation(s)
- C Inui-Yamamoto
- High Performance Bioimaging Research Facility, Graduate School of Frontier Biosciences, Osaka University, Suita 565-0871, Japan.
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44
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Devi L, Ohno M. Genetic reductions of beta-site amyloid precursor protein-cleaving enzyme 1 and amyloid-beta ameliorate impairment of conditioned taste aversion memory in 5XFAD Alzheimer's disease model mice. Eur J Neurosci 2009; 31:110-8. [PMID: 20092558 DOI: 10.1111/j.1460-9568.2009.07031.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Although transgenic mouse models of Alzheimer's disease (AD) recapitulate amyloid-beta (Abeta)-related pathologies and cognitive impairments, previous studies have mainly evaluated their hippocampus-dependent memory dysfunctions using behavioral tasks such as the water maze and fear conditioning. However, multiple memory systems become impaired in AD as the disease progresses and it is important to test whether other forms of memory are affected in AD models. This study was designed to use conditioned taste aversion (CTA) and contextual fear conditioning paradigms to compare the phenotypes of hippocampus-independent and -dependent memory functions, respectively, in 5XFAD amyloid precursor protein/presenilin-1 transgenic mice that harbor five familial AD mutations. Although both types of memory were significantly impaired in 5XFAD mice, the onset of CTA memory deficits ( approximately 9 months of age) was delayed compared with that of contextual memory deficits ( approximately 6 months of age). Furthermore, 5XFAD mice that were genetically engineered to have reduced levels of beta-site amyloid precursor protein-cleaving enzyme 1 (BACE1) (BACE1(+/-).5XFAD) exhibited improved CTA memory, which was equivalent to the performance of wild-type controls. Importantly, elevated levels of cerebral beta-secretase-cleaved C-terminal fragment (C99) and Abeta peptides in 5XFAD mice were significantly reduced in BACE1(+/-).5XFAD mice. Furthermore, Abeta deposition in the insular cortex and basolateral amygdala, two brain regions that are critically involved in CTA performance, was also reduced in BACE1(+/-).5XFAD compared with 5XFAD mice. Our findings indicate that the CTA paradigm is useful for evaluating a hippocampus-independent form of memory defect in AD model mice, which is sensitive to rescue by partial reductions of the beta-secretase BACE1 and consequently of cerebral Abeta.
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Affiliation(s)
- Latha Devi
- Center for Dementia Research, Nathan Kline Institute, New York University School of Medicine, 140 Old Orangeburg Road, Orangeburg, NY 10962, USA
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45
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Jonkman S, Everitt BJ. Post-learning infusion of anisomycin into the anterior cingulate cortex impairs instrumental acquisition through an effect on reinforcer valuation. Learn Mem 2009; 16:706-13. [PMID: 19864297 PMCID: PMC2775517 DOI: 10.1101/lm.1497709] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2009] [Accepted: 09/11/2009] [Indexed: 01/03/2023]
Abstract
The integrity of the rodent anterior cingulate cortex (ACC) is essential for various aspects of instrumental behavior, but it is not clear if the ACC is important for the acquisition of a simple instrumental response. Here, it was demonstrated that post-session infusions of anisomycin into the rat ACC completely prevented the acquisition of instrumental responding. The experimental use of post-session intracranial infusions of plasticity inhibitors is assumed to affect local consolidation of plasticity, but not behavioral task performance. However, in associative appetitive conditioning, post-session intracranial infusion of pharmaco-active compounds could actually interfere with subsequent task performance indirectly through retrospective effects on the valuation of ingested rewards. Thus, it was subsequently demonstrated that the intracranial infusion of anisomycin into the ACC after sucrose pellet consumption significantly reduced subsequent pellet consumption, suggesting that the infusion of anisomycin into the ACC produced conditioned taste avoidance. In the third experiment, an innovative procedure was introduced that dissociated the effects of intracranial infusions after conditioning sessions on task-learning and unconditioned stimulus valuation. With this procedure, the infusion of anisomycin into the ACC after instrumental sessions did not affect instrumental reinforcer valuation or the acquisition of instrumental responding, suggesting that plasticity in the ACC is not necessary for the acquisition of instrumental behavior.
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Affiliation(s)
- Sietse Jonkman
- Behavioural and Clinical Neuroscience Institute, Department of Experimental Psychology, University of Cambridge, Cambridge, United Kingdom.
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46
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Wang CC, Chai SC, Holahan MR. Effect of stimulus pre-exposure on inhibitory avoidance retrieval-associated changes in the phosphorylated form of the extracellular signal-regulated kinase-1 and -2 (pERK1/2). Neurobiol Learn Mem 2009; 93:66-76. [PMID: 19698796 DOI: 10.1016/j.nlm.2009.08.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 08/12/2009] [Accepted: 08/13/2009] [Indexed: 10/20/2022]
Abstract
One goal of the present study was to determine how pre-exposure to a set of contextual cues affected subsequent reinforced inhibitory avoidance task performance using those cues (latent inhibition model). In addition, immunohistochemical assessment of the phosphorylated (activated) form of the extracellular signal-regulated kinase-1 and -2 (pERK1/2) was examined. Adult, male Long Evans rats were randomly assigned into either pre-exposure (PE) or different pre-exposure (DPE) groups. All rats received 3days of contextual pre-exposure (same or different context as that used for reinforced training) and were trained, 24h later, on an inhibitory avoidance task (with or without shock). Rats were euthanized 24h after training; half with a retention test and half without. Behaviorally, the PE group showed reduced latencies to enter the dark/shock compartment during the retention test compared to the DPE group showing the latent inhibition phenomenon. Compared to the shocked and tested DPE group, the shocked and tested PE group showed fewer pERK1/2-ir neurons in the secondary motor cortex, the anterior cingulate, the pre- and infra-limbic cortices, and the central nucleus of the amygdala. These regions showed similar numbers of pERK1/2-labeled neurons when comparing the shocked and tested PE group with the nonshocked and tested PE group. This suggests the possibility that brain regions showing decreased pERK1/2 levels in association with attenuated inhibitory avoidance performance may be involved in different aspects of the memory retrieval process.
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Affiliation(s)
- Chia-Chuan Wang
- School of Medicine, Fu-Jen Catholic University, Taipei Hsien 242, Taiwan
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Shionoya K, Datiche F. Inactivation of the basolateral amygdala impairs the retrieval of recent and remote taste-potentiated odor aversion memory. Neurobiol Learn Mem 2009; 92:590-6. [PMID: 19643197 DOI: 10.1016/j.nlm.2009.07.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 06/20/2009] [Accepted: 07/22/2009] [Indexed: 11/19/2022]
Abstract
Memory reorganization as a time-dependent process can be investigated using various learning tasks such as the taste-potentiated odor aversion (TPOA). In this paradigm rats acquire a strong aversion to an olfactory cue presented simultaneously with a gustatory cue. Together these cues are paired with a delayed visceral illness. The basolateral amygdaloid nucleus (BLA) plays a key role in TPOA acquisition but its involvement in retrieval remains unclear. We investigated the involvement of the BLA in either recent or remote retrieval of TPOA. In each case, the number of licks observed in response to the presentation of either the odor or the taste was used to assess retrieval. Before the retrieval test, rats received a bilateral infusion of lidocaine to inactivate the BLA. We observed that both recent and remote TPOA retrieval tests induced by the odor presentation were disrupted in the lidocaine-injected rats. By contrast, the BLA inactivation had no effect upon the aversion towards the taste cue regardless of the time of retrieval. The present study provides evidence that BLA functioning is necessary for retrieval of aversive odor memory, even with a long post-acquisition delay.
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Affiliation(s)
- Kiseko Shionoya
- Centre Européen des Sciences du Goût, CNRS UMR 5170, 15 rue Hugues Picardet, 21000 Dijon, France.
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48
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Huynh DP, Maalouf M, Silva AJ, Schweizer FE, Pulst SM. Dissociated fear and spatial learning in mice with deficiency of ataxin-2. PLoS One 2009; 4:e6235. [PMID: 19617910 PMCID: PMC2707006 DOI: 10.1371/journal.pone.0006235] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Accepted: 06/17/2009] [Indexed: 11/18/2022] Open
Abstract
Mouse models with physiological and behavioral differences attributable to differential plasticity of hippocampal and amygdalar neuronal networks are rare. We previously generated ataxin-2 (Atxn2) knockout mice and demonstrated that these animals lacked obvious anatomical abnormalities of the CNS, but showed marked obesity and reduced fertility. We now report on behavioral changes as a consequence of Atxn2-deficiency. Atxn2-deficiency was associated with impaired long-term potentiation (LTP) in the amygdala, but normal LTP in the hippocampus. Intact hippocampal plasticity was associated behaviorally with normal Morris Water maze testing. Impaired amygdala plasticity was associated with reduced cued and contextual fear conditioning. Conditioned taste aversion, however, was normal. In addition, knockout mice showed decreased innate fear in several tests and motor hyperactivity in open cage testing. Our results suggest that Atxn2-deficiency results in a specific set of behavioral and cellular disturbances that include motor hyperactivity and abnormal fear-related behaviors, but intact hippocampal function. This animal model may be useful for the study of anxiety disorders and should encourage studies of anxiety in patients with spinocerebellar ataxia type 2 (SCA2).
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Affiliation(s)
- Duong P. Huynh
- Department of Neurology, University of Utah, Salt Lake City, Utah, United States of America
| | - Marwan Maalouf
- Department of Neurobiology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Alcino J. Silva
- Department of Neurobiology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Felix E. Schweizer
- Department of Neurobiology, University of California Los Angeles, Los Angeles, California, United States of America
| | - Stefan M. Pulst
- Department of Neurology, University of Utah, Salt Lake City, Utah, United States of America
- Brain Institute, University of Utah, Salt Lake City, Utah, United States of America
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Liu F, Zheng XL, Li BM. The anterior cingulate cortex is involved in retrieval of long-term/long-lasting but not short-term memory for step-through inhibitory avoidance in rats. Neurosci Lett 2009; 460:175-9. [PMID: 19450658 DOI: 10.1016/j.neulet.2009.05.032] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2009] [Revised: 04/21/2009] [Accepted: 05/12/2009] [Indexed: 11/26/2022]
Abstract
It is known that the anterior cingulate cortex (ACC) is involved in the formation of contextual fear memory. It has been shown that the ACC is important for the retrieval of long-term contextual fear memory. In order to further examine the role of the ACC in fear memory, we investigated the effects of chemical lesion to or reversible inactivation of the ACC on the retrieval of long-term and short-term step-through inhibitory avoidance (IA) memory. Chemical lesion to the ACC by quinolinic acid severely impaired the retrieval of 15-day and 29-day memories for one-trial step-through IA. Pre-retrieval inactivation of the ACC by locally infusing muscimol, a selective GABA(A) receptor agonist, produced a severe deficit in 7-day, 4-day and 1-day IA memories, with no effect on 2-h and 6-h memories. Thus, the ACC is required for the retrieval of long-term/long-lasting IA memory, but is dispensable for short-term one.
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Affiliation(s)
- Fang Liu
- Institute of Neurobiology and State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Fudan University, Shanghai 200032, China.
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50
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Akers KG, Frankland PW. Grading Gradients: Evaluating Evidence for Time-dependent Memory Reorganization in Experimental Animals. J Exp Neurosci 2009. [DOI: 10.4137/jen.s2391] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022] Open
Abstract
In humans, hippocampal damage typically produces temporally graded retrograde amnesia, with relative sparing of remote memories compared to recent memories. This observation led to the idea that as memories age, they are reorganized in a time-dependent manner. Here, we evaluate evidence for time-dependent memory reorganization in animal models. We conclude that, although hippocampal lesions may not always produce temporal gradients under all conditions, studies using alternate experimental approaches consistently support the idea that memories reorganize over time—becoming less dependent on the hippocampus and more dependent on a cortical network. We further speculate on the processes that drive memory reorganization such as sleep, memory reactivation, synaptic plasticity, and neurogenesis.
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Affiliation(s)
- Katherine G. Akers
- Neurosciences and Mental Health, Hospital for Sick Children, Toronto, Canada
| | - Paul W. Frankland
- Neurosciences and Mental Health, Hospital for Sick Children, Toronto, Canada
- Department of Physiology, University of Toronto, Toronto, Canada
- Institue of Medical Science, University of Toronto, Toronto, Canada
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