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Martin-Ordas G. The constructive nature of memories in insects: bumblebees as a case study. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230405. [PMID: 39278255 PMCID: PMC11449199 DOI: 10.1098/rstb.2023.0405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/13/2024] [Accepted: 04/26/2024] [Indexed: 09/18/2024] Open
Abstract
The view that human memory is constructive implies that recollections are not necessarily an accurate reproduction of past events. An approach to study this constructive nature of memory is by examining memory errors. In this regard, conjunction errors-i.e. incorrect recollection of new stimuli integrated by components from two previously studied stimuli-have attracted important attention in human memory research. Do animals other than humans make conjunction errors? To investigate this issue, a choice task in which training was not involved was used. Bees experienced two to-be-remembered stimuli. At the test, they were presented with four stimuli: one of the original items (i.e. old), an item made by combining two features of the original items (i.e. conjunction), an item containing a previously presented feature and a new one (i.e. feature), and an item integrated solely by new features (i.e. new). Bumblebees remembered the old items. Importantly, when making memory errors, bumblebees selected conjunction and feature lures more often than new items. These results indicate that bumblebees, like humans, spontaneously make memory conjunction errors and suggest that invertebrates' memories might also be constructive in nature. I suggest that focusing on memory errors is a solid avenue to investigate episodic (like) memory in animals.This article is part of the theme issue 'Elements of episodic memory: lessons from 40 years of research'.
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2
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Crystal JD. Mental time travel in the rat. Philos Trans R Soc Lond B Biol Sci 2024; 379:20230404. [PMID: 39278253 PMCID: PMC11449164 DOI: 10.1098/rstb.2023.0404] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2024] [Revised: 04/20/2024] [Accepted: 05/01/2024] [Indexed: 09/18/2024] Open
Abstract
I outline the perspective that searching the contents of memory is a form of mental time travel (MTT) in non-humans that is relatively tractable because it focuses on the contents of memory. I propose that an animal model of MTT requires three elements: (i) the animal remembers multiple events using episodic memory, (ii) the order of events in time is included in the representation, and (iii) the sequence of events can be searched to find a target that occurred at a particular time. I review experiments suggesting that rats represent multiple items in episodic memory (element 1) in order of occurrence (element 2) and engage in memory replay to search representations in episodic memory in sequential order to find information at particular points in the sequence (element 3). The cognitive building blocks needed for MTT may be quite old in the evolutionary timescale.This article is part of the theme issue 'Elements of episodic memory: lessons from 40 years of research'.
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Affiliation(s)
- Jonathon D Crystal
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10TH ST, Bloomington, IN 47405-7007, USA
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3
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Davies JR, Clayton NS. Is episodic-like memory like episodic memory? Philos Trans R Soc Lond B Biol Sci 2024; 379:20230397. [PMID: 39278246 PMCID: PMC11449162 DOI: 10.1098/rstb.2023.0397] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2024] [Revised: 03/15/2024] [Accepted: 03/22/2024] [Indexed: 09/18/2024] Open
Abstract
Episodic memory involves the conscious recollection of personally experienced events and when absent, results in profound losses to the typical human conscious experience. Over the last 2.5 decades, the debate surrounding whether episodic memory is unique to humans has seen a lot of controversy and accordingly has received significant research attention. Various behavioural paradigms have been developed to test episodic-like memory; a term designed to reflect the behavioural characteristics of episodic memory in the absence of evidence for consciously experienced recall. In this review, we first outline the most influential paradigms that have been developed to assess episodic-like memory across a variety of non-human taxa (including mammals, birds and cephalopods), namely the what-where-when memory, incidental encoding and unexpected question, and source memory paradigms. Then, we examine whether various key features of human episodic memory are conceptually represented in episodic-like memory across phylogenetically and neurologically diverse taxa, identifying similarities, differences and gaps in the literature. We conclude that the evidence is mixed, and as episodic memory encompasses a variety of cognitive structures and processes, research on episodic-like memory in non-humans should follow this multifaceted approach and assess evidence across various behavioural paradigms that each target different aspects of human episodic memory.This article is part of the theme issue 'Elements of episodic memory: lessons from 40 years of research'.
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Affiliation(s)
- James R Davies
- Department of Psychology, University of Cambridge, Cambridge CB2 3EB, UK
| | - Nicola S Clayton
- Department of Psychology, University of Cambridge, Cambridge CB2 3EB, UK
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Boyle A, Brown SAB. Why might animals remember? A functional framework for episodic memory research in comparative psychology. Learn Behav 2024:10.3758/s13420-024-00645-0. [PMID: 39289293 DOI: 10.3758/s13420-024-00645-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/23/2024] [Indexed: 09/19/2024]
Abstract
One of Clayton's major contributions to our understanding of animal minds has been her work on episodic-like memory. A central reason for the success of this work was its focus on ecological validity: rather than looking for episodic memory for arbitrary stimuli in artificial contexts, focussing on contexts in which episodic memory would serve a biological function such as food caching. This review aims to deepen this insight by surveying the numerous functions that have been proposed for episodic memory, articulating a philosophically grounded framework for understanding what exactly functions are, and drawing on these to make suggestions for future directions in the comparative cognitive psychology of episodic memory. Our review suggests four key insights. First, episodic memory may have more than one function and may have different functions in different species. Second, cross-disciplinary work is key to developing a functional account of episodic memory. Third, there is scope for further theoretical elaboration of proposals relating episodic memory to food caching and, in particular, future-oriented cognition. Finally, learning-related functions suggested by AI (artificial intelligence)-based models are a fruitful avenue for future behavioural research.
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Affiliation(s)
- Alexandria Boyle
- London School of Economics and Political Science, London, UK.
- CIFAR Azrieli Global Scholars Program, London, UK.
| | - Simon A B Brown
- London School of Economics and Political Science, London, UK
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Poncet L, Billard P, Clayton NS, Bellanger C, Jozet-Alves C. False memories in cuttlefish. iScience 2024; 27:110322. [PMID: 39258168 PMCID: PMC11384069 DOI: 10.1016/j.isci.2024.110322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2024] [Revised: 05/23/2024] [Accepted: 06/18/2024] [Indexed: 09/12/2024] Open
Abstract
Episodic memory is a reconstructive process per se: during an event, the features composing it are encoded and stored separately in the brain, then reconstructed when the event's memory is retrieved. Even with source monitoring processes (e.g., did I see or did I smell it?), some mistakes can occur. These mnemonic mistakes happen especially when different events share several features, producing overlaps difficult to discriminate, leading to the creation of false memories. The common cuttlefish has the ability to remember specific events about what happened where and when, namely episodic-like memory. In order to investigate whether this memory, such as human episodic memory, is based on reconstructive processes, we elaborated a protocol promoting false memory formation. Our results suggest that cuttlefish do form visual false memories, but not olfactory false memories. These memory errors might be the first indication of the presence of reconstructive processes in the memory of cephalopods.
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Affiliation(s)
- Lisa Poncet
- Normandie University, Unicaen, CNRS, EthoS, 14000 Caen, France
- University Rennes, CNRS, EthoS (Éthologie animale et humaine) - UMR 6552, F-35000 Rennes, France
| | - Pauline Billard
- Normandie University, Unicaen, CNRS, EthoS, 14000 Caen, France
- University Rennes, CNRS, EthoS (Éthologie animale et humaine) - UMR 6552, F-35000 Rennes, France
| | - Nicola S Clayton
- University of Cambridge, Department of Psychology, Cambridge CB2 3EB, UK
| | - Cécile Bellanger
- Normandie University, Unicaen, CNRS, EthoS, 14000 Caen, France
- University Rennes, CNRS, EthoS (Éthologie animale et humaine) - UMR 6552, F-35000 Rennes, France
| | - Christelle Jozet-Alves
- Normandie University, Unicaen, CNRS, EthoS, 14000 Caen, France
- University Rennes, CNRS, EthoS (Éthologie animale et humaine) - UMR 6552, F-35000 Rennes, France
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6
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Kunčická D, Krajčovič B, Stuchlík A, Brožka H. Neuroscientist's Behavioral Toolbox for Studying Episodic-Like Memory. eNeuro 2024; 11:ENEURO.0073-24.2024. [PMID: 39214694 PMCID: PMC11366770 DOI: 10.1523/eneuro.0073-24.2024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2024] [Revised: 07/12/2024] [Accepted: 07/22/2024] [Indexed: 09/04/2024] Open
Abstract
Episodic memory, the ability to recall specific events and experiences, is a cornerstone of human cognition with profound clinical implications. While animal studies have provided valuable insights into the neuronal underpinnings of episodic memory, research has largely relied on a limited subset of tasks that model only some aspects of episodic memory. In this narrative review, we provide an overview of rodent episodic-like memory tasks that expand the methodological repertoire and diversify the approaches used in episodic-like memory research. These tasks assess various aspects of human episodic memory, such as integrated what-where-when or what-where memory, source memory, free recall, temporal binding, and threshold retrieval dynamics. We review each task's general principle and consider whether alternative non-episodic mechanisms can account for the observed behavior. While our list of tasks is not exhaustive, we hope it will guide researchers in selecting models that align with their specific research objectives, leading to novel advancements and a more comprehensive understanding of mechanisms underlying specific aspects of episodic memory.
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Affiliation(s)
- Daniela Kunčická
- Laboratory of Neurophysiology of Memory, Institute of Physiology, Czech Academy of Sciences, Prague 142 20, Czechia
| | - Branislav Krajčovič
- Department of Physiology, Second Faculty of Medicine, Charles University, Prague 150 06, Czechia
| | - Aleš Stuchlík
- Laboratory of Neurophysiology of Memory, Institute of Physiology, Czech Academy of Sciences, Prague 142 20, Czechia
| | - Hana Brožka
- Laboratory of Neurophysiology of Memory, Institute of Physiology, Czech Academy of Sciences, Prague 142 20, Czechia
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7
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Tanaka C, Taniuchi T. Rats show up to 72 h of significant retention for spatial memory in the radial maze. Learn Behav 2024:10.3758/s13420-024-00633-4. [PMID: 39048834 DOI: 10.3758/s13420-024-00633-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/21/2024] [Indexed: 07/27/2024]
Abstract
This study explored long-term retention of spatial memory in rats using an eight-arm radial maze. Crystal and Babb (Learning and motivation, 39(4), 278-284, 2008) previously demonstrated that rats could retain spatial memory for up to 25 h in the radial maze. Notably, they found performance improved with 48-h intertrial intervals compared with 24-h intervals. Our study investigated the effects of extending intertrial intervals on long-term retention of spatial memory by reducing the potential for proactive interference. Each trial comprised a learning phase, during which subjects were required to sequentially visit four randomly selected arms, followed by a free-choice test that included all eight arms, conducted after increasing the retention and intertrial intervals. The retention intervals were systematically increased from 1 h to 24, 48, and, ultimately, 72 h, with corresponding intertrial intervals expanding from 24 to 48, 120, and 144 h. Performance significantly surpassed chance levels across all conditions, demonstrating that rats are capable of retaining spatial memory for up to 72 h.
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Affiliation(s)
- Chiaki Tanaka
- Graduate School of Socio-Environmental Studies, Kanazawa University, Kakuma, Kanazawa, Ishikawa, 920-1192, Japan
| | - Tohru Taniuchi
- Graduate School of Socio-Environmental Studies, Kanazawa University, Kakuma, Kanazawa, Ishikawa, 920-1192, Japan.
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Sheridan CL, Panoz-Brown D, Shiffrin RM, Crystal JD. Validation of a rodent model of episodic memory replay. Learn Behav 2024:10.3758/s13420-024-00632-5. [PMID: 39020162 DOI: 10.3758/s13420-024-00632-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/12/2024] [Indexed: 07/19/2024]
Abstract
Vivid episodic memories in humans have been described as the replay of the flow of past events in sequential order. Recently, Panoz-Brown et al. Current Biology, 28, 1628-1634, (2018) developed an olfactory memory task in which rats were presented with a list of trial-unique odors in an encoding context; next, in a distinctive memory assessment context, the rats were rewarded for choosing the second to last item from the list while avoiding other items from the list. In a different memory assessment context, the fourth to last item was rewarded. According to the episodic memory replay hypothesis, the rat remembers the list items and searches these items to find the item at the targeted locations in the list. However, events presented sequentially differ in memory trace strength, allowing a rat to use the relative familiarity of the memory traces, instead of episodic memory replay, to solve the task. Here, we directly manipulated memory trace strength by manipulating the odor intensity of target odors in both the list presentation and memory assessment. The rats relied on episodic memory replay to solve the memory assessment in conditions in which reliance on memory trace strength is ruled out. We conclude that rats are able to replay episodic memories.
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Affiliation(s)
- Cassandra L Sheridan
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10TH St., Bloomington, IN, 47405, USA
| | - Danielle Panoz-Brown
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10TH St., Bloomington, IN, 47405, USA
| | - Richard M Shiffrin
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10TH St., Bloomington, IN, 47405, USA
| | - Jonathon D Crystal
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10TH St., Bloomington, IN, 47405, USA.
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Sheridan CL, Bonner L, Crystal JD. Replay of incidentally encoded novel odors in the rat. Anim Cogn 2024; 27:43. [PMID: 38874623 PMCID: PMC11178560 DOI: 10.1007/s10071-024-01880-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2024] [Revised: 05/28/2024] [Accepted: 05/29/2024] [Indexed: 06/15/2024]
Abstract
Although events are not always known to be important when they occur, people can remember details about such incidentally encoded information using episodic memory. Sheridan et al. (2024) argued that rats replayed episodic memories of incidentally encoded information in an unexpected assessment of memory. In one task, rats reported the third-last item in an explicitly encoded list of trial-unique odors. In a second task, rats foraged in a radial maze in the absence of odors. On a critical test, rats foraged in the maze, but scented lids covered the food. Next, memory of the third-last odor was assessed. The rats correctly answered the unexpected question. Because the odors used in the critical test were the same as those used during training, automatically encoding odors for the purpose of taking an upcoming test of memory (stimulus generalization) may have been encouraged. Here, we provided an opportunity for incidental encoding of novel odors. Previously trained rats foraged in the radial maze with entirely novel odors covering the food. Next, memory of the third-last odor was assessed. The rats correctly answered the unexpected question. High accuracy when confronted with novel odors provides evidence that the rats did not automatically encode odors for the purpose of taking an upcoming test, ruling out stimulus generalization. We conclude that rats encode multiple pieces of putatively unimportant information, and later replayed a stream of novel episodic memories when that information was needed to solve an unexpected problem.
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Affiliation(s)
- Cassandra L Sheridan
- Department of Psychological & Brain Sciences, Indiana University, Bloomington, IN, USA
| | - Lauren Bonner
- Department of Psychological & Brain Sciences, Indiana University, Bloomington, IN, USA
| | - Jonathon D Crystal
- Department of Psychological & Brain Sciences, Indiana University, Bloomington, IN, USA.
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10
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Sheridan CL, Lang S, Knappenberger M, Albers C, Loper R, Tillett B, Sanchez J, Wilcox A, Harrison T, Panoz-Brown D, Crystal JD. Replay of incidentally encoded episodic memories in the rat. Curr Biol 2024; 34:641-647.e5. [PMID: 38218186 DOI: 10.1016/j.cub.2023.12.043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 04/03/2023] [Accepted: 12/13/2023] [Indexed: 01/15/2024]
Abstract
Although events are not always known to be important when they occur, people can remember details about such incidentally encoded information using episodic memory. Importantly, when information is explicitly encoded for use in an expected test of retention (as in most assessments in animals), it is possible that it is used to generate a planned action1,2,3; thus, the remembered action can occur without remembering the earlier episode. By contrast, when a test is unexpected, transforming information into an action plan is unlikely because the importance of the information and the nature of the test are not yet known. Thus, accurate performance in an unexpected test after incidental encoding documents episodic memory.1,2,3,4,5,6,7,8 Here, we present evidence that rats replay episodic memories of incidentally encoded information in an unexpected assessment of memory. In one task,9 rats reported the third-last item in an explicitly encoded list of trial-unique odors. In a second task,10 rats foraged in a radial maze in the absence of odors. On a critical test, rats foraged in the radial maze, but scented lids covered the food. Next, memory of the third-last odor was assessed. All participating rats correctly answered the unexpected question. These results suggest that rats encoded multiple pieces of putatively unimportant information, and later they replayed a stream of episodic memories when that information was needed to solve an unexpected problem. We propose that rats replay episodic memories of incidentally encoded information, which documents a critical aspect of human episodic memory in a non-human animal.
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Affiliation(s)
- Cassandra L Sheridan
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10(TH) ST, Bloomington, IN 47405-7007, USA
| | - Stephen Lang
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10(TH) ST, Bloomington, IN 47405-7007, USA
| | - Mya Knappenberger
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10(TH) ST, Bloomington, IN 47405-7007, USA
| | - Cami Albers
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10(TH) ST, Bloomington, IN 47405-7007, USA
| | - Ryleigh Loper
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10(TH) ST, Bloomington, IN 47405-7007, USA
| | - Baily Tillett
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10(TH) ST, Bloomington, IN 47405-7007, USA
| | - Jonah Sanchez
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10(TH) ST, Bloomington, IN 47405-7007, USA
| | - Alyssa Wilcox
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10(TH) ST, Bloomington, IN 47405-7007, USA
| | - Tess Harrison
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10(TH) ST, Bloomington, IN 47405-7007, USA
| | - Danielle Panoz-Brown
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10(TH) ST, Bloomington, IN 47405-7007, USA
| | - Jonathon D Crystal
- Department of Psychological and Brain Sciences, Indiana University, 1101 E 10(TH) ST, Bloomington, IN 47405-7007, USA.
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Parent MB. Using Postmeal Measures and Manipulations to Investigate Hippocampal Mnemonic Control of Eating Behavior. Neuroscience 2022; 497:228-238. [PMID: 34998891 PMCID: PMC9256844 DOI: 10.1016/j.neuroscience.2021.12.040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2021] [Revised: 12/27/2021] [Accepted: 12/30/2021] [Indexed: 10/19/2022]
Abstract
Episodic meal-related memories provide the brain with a powerful mechanism for tracking and controlling eating behavior because they contain a detailed record of recent energy intake that likely outlasts the physiological signals generated by feeding bouts. This review briefly summarizes evidence from human participants showing that episodic meal-related memory limits later eating behavior and then describes our research aimed at investigating whether hippocampal neurons mediate the inhibitory effects of meal-related memory on subsequent feeding. Our approach has been inspired by pioneering work conducted by Ivan Izquierdo and others who used posttraining manipulations to investigate memory consolidation. This review describes the rationale and value of posttraining manipulations, how Izquierdo used them to demonstrate that dorsal hippocampal (dHC) neurons are critical for memory consolidation, and how we have adapted this strategy to investigate whether dHC neurons are necessary for mnemonic control of energy intake. I describe our evidence showing that ingestion activates the molecular processes necessary for synaptic plasticity and memory during the early postprandial period, when the memory of the meal would be undergoing consolidation, and then summarize our findings showing that neural activity in dHC neurons is critical during the early postprandial period for limiting future intake. Collectively, our evidence supports the hypothesis that dHC neurons mediate the inhibitory effects of ingestion-related memory on future intake and demonstrates that post-experience memory modulation is not confined to artificial laboratory memory tasks.
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Affiliation(s)
- M B Parent
- Neuroscience Institute & Department of Psychology, Georgia State University, PO Box 5030, Atlanta, GA 30303, USA.
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12
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Dias ALA, de Oliveira Golzio AMF, de Lima Santos BH, da Silva Stiebbe Salvadori MG, Dos Santos SG, da Silva MS, de Almeida RN, Barbosa FF. Post-learning caffeine administration improves 'what-when' and 'what-where' components of episodic-like memory in rats. Behav Brain Res 2022; 433:113982. [PMID: 35779707 DOI: 10.1016/j.bbr.2022.113982] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Revised: 05/30/2022] [Accepted: 06/27/2022] [Indexed: 11/02/2022]
Abstract
Episodic-like memory (ELM) consists in the capacity of nonhuman animals to remember 'where' and 'when' a specific episode occurred ('what'). Previous studies have showed that Wistar rats can form an ELM, but not after a 24 h retention delay. On the other hand, it has been demonstrated that caffeine can improve episodic memory consolidation in humans. Therefore, we verified whether acute post-sample caffeine administration could improve ELM consolidation in Wistar rats, as well if it could be related to neurochemical changes in the prefrontal cortex and hippocampus - regions related to episodic-like memory processing. 46 Male Wistar Rats, approximately 3 months-old, were divided into four groups as follows: untreated (n = 11), saline (n = 11), caffeine 10 mg ∕kg i.p (n = 12); caffeine 15 mg∕kgi.p (n = 12) and tested in WWWhen/ELM task. The animals treated with caffeine in different dosages (10 mg/kg and 15 mg/kg) discriminated temporally and spatially the objects, respectively. These groups also showed a dopamine renewal rate in the hippocampus, suggesting that there was an increase in the turnover compared with the groups with no caffeine administration. We can conclude that caffeine leads to an improvement in the consolidation of the temporal ('what-when') and spatial ('what-where') aspects of episodic-like memory.
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Affiliation(s)
| | | | | | - Mirian Graciela da Silva Stiebbe Salvadori
- Departamento de Psicologia, Programa de Pós-Graduação em Neurociência Cognitiva e Comportamento, Centro de Ciências Humanas, Letras e Artes, Universidade Federal da Paraíba, Brazil
| | - Sócrates Golzio Dos Santos
- Departamento de Ciências Farmacêuticas, Centro de Ciências da Saúde, Universidade Federal da Paraíba, Brazil
| | - Marcelo Sobral da Silva
- Departamento de Ciências Farmacêuticas, Centro de Ciências da Saúde, Universidade Federal da Paraíba, Brazil
| | - Reinaldo Nóbrega de Almeida
- Programa de Produtos Naturais e Sintéticos Bioativos, Centro de Ciências da Saúde, Universidade Federal da Paraíba, Brazil
| | - Flavio Freitas Barbosa
- Departamento de Psicologia, Programa de Pós-Graduação em Neurociência Cognitiva e Comportamento, Centro de Ciências Humanas, Letras e Artes, Universidade Federal da Paraíba, Brazil.
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13
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Parent MB, Higgs S, Cheke LG, Kanoski SE. Memory and eating: A bidirectional relationship implicated in obesity. Neurosci Biobehav Rev 2022; 132:110-129. [PMID: 34813827 PMCID: PMC8816841 DOI: 10.1016/j.neubiorev.2021.10.051] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 10/17/2021] [Accepted: 10/28/2021] [Indexed: 01/03/2023]
Abstract
This paper reviews evidence demonstrating a bidirectional relationship between memory and eating in humans and rodents. In humans, amnesia is associated with impaired processing of hunger and satiety cues, disrupted memory of recent meals, and overconsumption. In healthy participants, meal-related memory limits subsequent ingestive behavior and obesity is associated with impaired memory and disturbances in the hippocampus. Evidence from rodents suggests that dorsal hippocampal neural activity contributes to the ability of meal-related memory to control future intake, that endocrine and neuropeptide systems act in the ventral hippocampus to provide cues regarding energy status and regulate learned aspects of eating, and that consumption of hypercaloric diets and obesity disrupt these processes. Collectively, this evidence indicates that diet-induced obesity may be caused and/or maintained, at least in part, by a vicious cycle wherein excess intake disrupts hippocampal functioning, which further increases intake. This perspective may advance our understanding of how the brain controls eating, the neural mechanisms that contribute to eating-related disorders, and identify how to treat diet-induced obesity.
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Affiliation(s)
- Marise B Parent
- Neuroscience Institute & Department of Psychology, Georgia State University, Box 5030, Atlanta, GA 30303-5030, United States.
| | - Suzanne Higgs
- School of Psychology, University of Birmingham, Edgbaston, Birmingham, BI5 2TT, United Kingdom.
| | - Lucy G Cheke
- Department of Psychology, University of Cambridge, Downing Street, Cambridge, CB2 3EB, United Kingdom.
| | - Scott E Kanoski
- Department of Biological Sciences, Human and Evolutionary Biology Section, University of Southern California, Los Angeles, CA, 90089-0371, United States.
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Numan R. The Prefrontal-Hippocampal Comparator: Volition and Episodic Memory. Percept Mot Skills 2021; 128:2421-2447. [PMID: 34424092 DOI: 10.1177/00315125211041341] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
This review describes recent research that is relevant to the prefrontal-hippocampal comparator model with the following conclusions: 1. Hippocampal area CA1 serves, at least in part, as an associative match-mismatch comparator. 2. Voluntary movement strengthens episodic memories for goal-directed behavior. 3. Hippocampal theta power serves as a prediction error signal during hippocampal dependent tasks. 4. The self-referential component of episodic memory in humans is mediated by the corollary discharge (the efference copy of the action plan developed by prefrontal cortex and transmitted to hippocampus where it is stored as a working memory; CA1 uses this efference copy to compare the expected consequences of action to the actual consequences of action). 5. Impairments in the production or transmission of this corollary discharge may contribute to some of the symptoms of schizophrenia. Unresolved issues and suggestions for future research are discussed.
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Affiliation(s)
- Robert Numan
- Department of Psychology, Santa Clara University, Santa Clara, California, United States
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15
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Yi X, Yi S, Deng Y, Wang M, Ju M. High-valued seeds are remembered better: evidence for item-based spatial memory of scatter-hoarding rodents. Anim Behav 2021. [DOI: 10.1016/j.anbehav.2021.02.009] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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16
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Abstract
Experimental psychologist Jonathan Crystal and evolutionary psychologist Thomas Suddendorf debate with nonhuman animals experience human-like episodic memory.
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17
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Hirata S, Betsuyaku T, Fujita K, Nakano T, Ikegaya Y. Phylogeny and ontogeny of mental time. Neurosci Res 2020; 170:13-17. [PMID: 32681853 DOI: 10.1016/j.neures.2020.07.008] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2020] [Revised: 07/08/2020] [Accepted: 07/13/2020] [Indexed: 11/18/2022]
Abstract
Humans have mental time in our mind, apart from physical time that is a part of system that governs the physical world, and memory is our key cognitive ability for recognizing the passage of time. Recent studies have suggested that the memory system of several nonhuman animals may have an incidental nature, which is also a feature of episodic memory. In addition, apes, which are phylogenetically close to humans, have an ability to remember a single past event. In the case of humans, preverbal infants under the age of two are able to retain long-term memory of a single event and apply it to predict a future event. Thus, nonhuman animals and preverbal human infants both have their own specific mental time travel abilities, and there is a phylogenetic and ontogenic basis of full-fledged mental time travel that can be found in human adults.
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Affiliation(s)
- Satoshi Hirata
- Wildlife Research Center, Kyoto University, Kyoto 606-8203, Japan
| | - Toru Betsuyaku
- Graduate School of Letters, Kyoto University, Kyoto 606-8501, Japan
| | - Kazuo Fujita
- Graduate School of Letters, Kyoto University, Kyoto 606-8501, Japan
| | - Tamami Nakano
- Graduate School of Frontier Biosciences, Osaka University, 565-0871, Japan
| | - Yuji Ikegaya
- Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo 113-0033, Japan; Center for Information and Neural Networks, National Institute of Information and Communications Technology, Suita City, Osaka, 565-0871, Japan.
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18
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Basile BM, Templer VL, Gazes RP, Hampton RR. Preserved visual memory and relational cognition performance in monkeys with selective hippocampal lesions. SCIENCE ADVANCES 2020; 6:eaaz0484. [PMID: 32832615 PMCID: PMC7439495 DOI: 10.1126/sciadv.aaz0484] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 06/01/2020] [Indexed: 06/11/2023]
Abstract
The theory that the hippocampus is critical for visual memory and relational cognition has been challenged by discovery of more spared hippocampal tissue than previously reported in H.M., previously unreported extra-hippocampal damage in developmental amnesiacs, and findings that the hippocampus is unnecessary for object-in-context memory in monkeys. These challenges highlight the need for causal tests of hippocampal function in nonhuman primate models. Here, we tested rhesus monkeys on a battery of cognitive tasks including transitive inference, temporal order memory, shape recall, source memory, and image recognition. Contrary to predictions, we observed no robust impairments in memory or relational cognition either within- or between-groups following hippocampal damage. These results caution against over-generalizing from human correlational studies or rodent experimental studies, compel a new generation of nonhuman primate studies, and indicate that we should reassess the relative contributions of the hippocampus proper compared to other regions in visual memory and relational cognition.
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Affiliation(s)
- Benjamin M. Basile
- Department of Psychology and Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA
- Section on the Neurobiology of Learning and Memory, Laboratory of Neuropsychology, National Institute of Mental Health, NIH, Bethesda, MD, USA
| | - Victoria L. Templer
- Department of Psychology and Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA
- Department of Psychology, Providence College, Providence, RI, USA
| | - Regina Paxton Gazes
- Department of Psychology and Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA
- Department of Psychology and Program in Animal Behavior, Bucknell University, Lewisburg, PA, USA
| | - Robert R. Hampton
- Department of Psychology and Yerkes National Primate Research Center, Emory University, Atlanta, GA, USA
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Crystal JD. Memory: Amyloid Beta Is Good Before It Is Bad. Curr Biol 2020; 30:R449-R450. [PMID: 32428478 DOI: 10.1016/j.cub.2020.03.024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
A fundamental mystery in the biology of memory is to understand the pathway from normal memory to later dysfunctional memory. Some insight on this problem comes from new research suggesting that amyloid beta helps memory consolidation, before it impairs memory.
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Affiliation(s)
- Jonathon D Crystal
- Department of Psychological and Brain Sciences, Indiana University, 1101 E. 10th Street, Bloomington, IN 47405-7007, USA.
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20
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The medial prefrontal cortex - hippocampus circuit that integrates information of object, place and time to construct episodic memory in rodents: Behavioral, anatomical and neurochemical properties. Neurosci Biobehav Rev 2020; 113:373-407. [PMID: 32298711 DOI: 10.1016/j.neubiorev.2020.04.007] [Citation(s) in RCA: 86] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2019] [Revised: 02/25/2020] [Accepted: 04/06/2020] [Indexed: 12/31/2022]
Abstract
Rats and mice have been demonstrated to show episodic-like memory, a prototype of episodic memory, as defined by an integrated memory of the experience of an object or event, in a particular place and time. Such memory can be assessed via the use of spontaneous object exploration paradigms, variably designed to measure memory for object, place, temporal order and object-location inter-relationships. We review the methodological properties of these tests, the neurobiology about time and discuss the evidence for the involvement of the medial prefrontal cortex (mPFC), entorhinal cortex (EC) and hippocampus, with respect to their anatomy, neurotransmitter systems and functional circuits. The systematic analysis suggests that a specific circuit between the mPFC, lateral EC and hippocampus encodes the information for event, place and time of occurrence into the complex episodic-like memory, as a top-down regulation from the mPFC onto the hippocampus. This circuit can be distinguished from the neuronal component memory systems for processing the individual information of object, time and place.
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21
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Billard P, Clayton NS, Jozet-Alves C. Cuttlefish retrieve whether they smelt or saw a previously encountered item. Sci Rep 2020; 10:5413. [PMID: 32214190 PMCID: PMC7096502 DOI: 10.1038/s41598-020-62335-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 02/24/2020] [Indexed: 11/15/2022] Open
Abstract
According to the Source Monitoring Framework, the origin of a memory is remembered through the retrieval of specific features (e.g. perceptive, sensitive, affective signals). In two source discrimination tasks, we studied the ability of cuttlefish to remember the modality in which an item had been presented several hours ago. In Experiment 1, cuttlefish were able to retrieve the modality of presentation of a crab (visual vs olfactory) sensed before 1 h and 3 hrs delays. In Experiment 2, cuttlefish were trained to retrieve the modality of the presentation of fish, shrimp, and crabs. After training, cuttlefish performed the task with another item never encountered before (e.g. mussel). The cuttlefish successfully passed transfer tests with and without a delay of 3 hrs. This study is the first to show the ability to discriminate between two sensory modalities (i.e. see vs smell) in an animal. Taken together, these results suggest that cuttlefish can retrieve perceptual features of a previous event, namely whether they had seen or smelled an item.
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Affiliation(s)
- P Billard
- Normandie Univ, Unicaen, CNRS, EthoS, 14000, Caen, France.
- Univ Rennes, CNRS, EthoS (Éthologie animale et humaine) - UMR 6552, F-35000, Rennes, France.
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK.
| | - N S Clayton
- Department of Psychology, University of Cambridge, Cambridge, CB2 3EB, UK
| | - C Jozet-Alves
- Normandie Univ, Unicaen, CNRS, EthoS, 14000, Caen, France
- Univ Rennes, CNRS, EthoS (Éthologie animale et humaine) - UMR 6552, F-35000, Rennes, France
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22
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Replay of Episodic Memories in the Rat. Curr Biol 2018; 28:1628-1634.e7. [PMID: 29754898 DOI: 10.1016/j.cub.2018.04.006] [Citation(s) in RCA: 47] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Revised: 03/05/2018] [Accepted: 04/03/2018] [Indexed: 01/01/2023]
Abstract
Vivid episodic memories in people have been characterized as the replay of multiple unique events in sequential order [1-3]. The hippocampus plays a critical role in episodic memories in both people and rodents [2, 4-6]. Although rats remember multiple unique episodes [7, 8], it is currently unknown if animals "replay" episodic memories. Therefore, we developed an animal model of episodic memory replay. Here, we show that rats can remember a trial-unique stream of multiple episodes and the order in which these events occurred by engaging hippocampal-dependent episodic memory replay. We document that rats rely on episodic memory replay to remember the order of events rather than relying on non-episodic memories. Replay of episodic memories survives a long retention-interval challenge and interference from the memory of other events, which documents that replay is part of long-term episodic memory. The chemogenetic activating drug clozapine N-oxide (CNO), but not vehicle, reversibly impairs episodic memory replay in rats previously injected bilaterally in the hippocampus with a recombinant viral vector containing an inhibitory designer receptor exclusively activated by a designer drug (DREADD; AAV8-hSyn-hM4Di-mCherry). By contrast, two non-episodic memory assessments are unaffected by CNO, showing selectivity of this hippocampal-dependent impairment. Our approach provides an animal model of episodic memory replay, a process by which the rat searches its representations in episodic memory in sequential order to find information. Our findings using rats suggest that the ability to replay a stream of episodic memories is quite old in the evolutionary timescale.
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23
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Korsós G, Horváth K, Lukács A, Vezér T, Glávits R, Fodor K, Fekete SG. Effects of accelerated human music on learning and memory performance of rats. Appl Anim Behav Sci 2018. [DOI: 10.1016/j.applanim.2018.01.011] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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24
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Abstract
Humans engage in exchanges of commodities or services, often paying back a commodity with a different service. New research suggests that rats can reciprocally trade food for allogrooming, and vice versa.
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25
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Dalecki SJ, Panoz-Brown DE, Crystal JD. A test of the reward-contrast hypothesis. Behav Processes 2017; 145:15-17. [PMID: 28965970 PMCID: PMC5681873 DOI: 10.1016/j.beproc.2017.09.018] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2017] [Revised: 09/26/2017] [Accepted: 09/27/2017] [Indexed: 11/18/2022]
Abstract
Source memory, a facet of episodic memory, is the memory of the origin of information. Whereas source memory in rats is sustained for at least a week, spatial memory degraded after approximately a day. Different forgetting functions may suggest that two memory systems (source memory and spatial memory) are dissociated. However, in previous work, the two tasks used baiting conditions consisting of chocolate and chow flavors; notably, the source memory task used the relatively better flavor. Thus, according to the reward-contrast hypothesis, when chocolate and chow were presented within the same context (i.e., within a single radial maze trial), the chocolate location was more memorable than the chow location because of contrast. We tested the reward-contrast hypothesis using baiting configurations designed to produce reward-contrast. The reward-contrast hypothesis predicts that under these conditions, spatial memory will survive a 24-h retention interval. We documented elimination of spatial memory performance after a 24-h retention interval using a reward-contrast baiting pattern. These data suggest that reward contrast does not explain our earlier findings that source memory survives unusually long retention intervals.
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Affiliation(s)
- Stefan J Dalecki
- Department of Psychological and Brain Sciences, Indiana University, IN 47405, United States
| | - Danielle E Panoz-Brown
- Department of Psychological and Brain Sciences, Indiana University, IN 47405, United States
| | - Jonathon D Crystal
- Department of Psychological and Brain Sciences, Indiana University, IN 47405, United States.
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26
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Rhesus monkeys (Macaca mulatta) remember agency information from past events and integrate this knowledge with spatial and temporal features in working memory. Anim Cogn 2017; 21:137-153. [DOI: 10.1007/s10071-017-1147-x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Revised: 11/03/2017] [Accepted: 11/25/2017] [Indexed: 10/18/2022]
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27
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Templer VL, Lee KA, Preston AJ. Rats know when they remember: transfer of metacognitive responding across odor-based delayed match-to-sample tests. Anim Cogn 2017; 20:891-906. [PMID: 28669115 PMCID: PMC5709207 DOI: 10.1007/s10071-017-1109-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2016] [Revised: 06/15/2017] [Accepted: 06/23/2017] [Indexed: 10/19/2022]
Abstract
Metamemory entails cognitively assessing the strength of one's memories. We tested the ability of nine Long-Evans rats to distinguish between remembering and forgetting by presenting a decline option that allowed a four-choice odor-based delayed match to sample (DMTS) tests to be by-passed. Rats performed significantly better on tests they chose to take than on tests they were forced to take, indicating metacognitive responding. However, rather than control by internal mnemonic cues, one alternative explanation is that decline use is based on external test-specific cues that become associated with increased rewards overtime. To examine this possibility, we tested rats on three generalization tests in which external contingencies were inconsistent and therefore could not serve as discriminative cues. Rats transferred adaptive use of the decline response in tests that eliminated memory by presenting no sample, increased memory by presenting multiple samples, and both weakened and strengthened memory by varying the retention interval. Further, subjects chose to take or decline the test before encountering the memory test, providing evidence that rats based their metacognitive responding on internal cues rather than external ones. To our knowledge, this is the first robust evidence for metamemory in rats using the DMTS decline-test paradigm in which several possible sources of external stimulus control can be ruled out.
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Affiliation(s)
- Victoria L Templer
- Department of Psychology, Providence College, 1 Cunningham Square, Providence, RI, 02918, USA.
| | - Keith A Lee
- Department of Psychology, Providence College, 1 Cunningham Square, Providence, RI, 02918, USA
| | - Aidan J Preston
- Department of Psychology, Providence College, 1 Cunningham Square, Providence, RI, 02918, USA
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28
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Panoz-Brown D, Carey LM, Smith AE, Gentry M, Sluka CM, Corbin HE, Wu JE, Hohmann AG, Crystal JD. The chemotherapeutic agent paclitaxel selectively impairs reversal learning while sparing prior learning, new learning and episodic memory. Neurobiol Learn Mem 2017; 144:259-270. [PMID: 28811227 DOI: 10.1016/j.nlm.2017.08.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2017] [Revised: 08/07/2017] [Accepted: 08/10/2017] [Indexed: 12/18/2022]
Abstract
Chemotherapy is widely used to treat patients with systemic cancer. The efficacy of cancer therapies is frequently undermined by adverse side effects that have a negative impact on the quality of life of cancer survivors. Cancer patients who receive chemotherapy often experience chemotherapy-induced cognitive impairment across a variety of domains including memory, learning, and attention. In the current study, the impact of paclitaxel, a taxane derived chemotherapeutic agent, on episodic memory, prior learning, new learning, and reversal learning were evaluated in rats. Neurogenesis was quantified post-treatment in the dentate gyrus of the same rats using immunostaining for 5-Bromo-2'-deoxyuridine (BrdU) and Ki67. Paclitaxel treatment selectively impaired reversal learning while sparing episodic memory, prior learning, and new learning. Furthermore, paclitaxel-treated rats showed decreases in markers of hippocampal cell proliferation, as measured by markers of cell proliferation assessed using immunostaining for Ki67 and BrdU. This work highlights the importance of using multiple measures of learning and memory to identify the pattern of impaired and spared aspects of chemotherapy-induced cognitive impairment.
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Affiliation(s)
- Danielle Panoz-Brown
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Lawrence M Carey
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Alexandra E Smith
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Meredith Gentry
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Christina M Sluka
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Hannah E Corbin
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Jie-En Wu
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Andrea G Hohmann
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States; Gill Center for Biomolecular Science, Indiana University, Bloomington, IN, United States.
| | - Jonathon D Crystal
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States.
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29
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Lewis A, Call J, Berntsen D. Non-goal-directed recall of specific events in apes after long delays. Proc Biol Sci 2017; 284:20170518. [PMID: 28701556 PMCID: PMC5524493 DOI: 10.1098/rspb.2017.0518] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Accepted: 06/06/2017] [Indexed: 01/02/2023] Open
Abstract
We examined if apes spontaneously remember one-time, distinctive events across long delays when probed by discriminant cues. Apes witnessed an experimenter hide a cache of food, which they could then retrieve. They retrieved one of two food types; one more distinctive than the other. Two, 10 or 50 weeks later, the apes returned to the same enclosure and found a piece of the previously hidden food on the ground. An experimenter who had not hidden the food was also present. Apes immediately searched the location where the food was previously hidden (no food was here), showing recall of the event. One week later, apes returned to the same enclosure, with the same food on the ground, but now the experimenter that had hidden the food was present. Again, apes immediately searched the hiding location. Apes that had not witnessed the hiding event did not search. There was no significant effect of food type, and retention declined from exposure to the two-week delay, then levelled, consistent with the forgetting curve in humans (Ebbinghaus, H. 1964 Memory: a contribution to experimental psychology (transl. H.A. Ruger & C.E. Bussenvis). New York, NY: Dover. (Original work published 1885.)). This is the first study to show apes can recall a one-time, non-goal-directed event longer than two weeks ago and that apes' recall declines in accordance with a standard retention function.
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Affiliation(s)
- Amy Lewis
- School of Psychology and Neuroscience, University of St Andrews, St Mary's Quad, South Street, St Andrews, Fife KY16 9JP, UK
- Center on Autobiographical Memory Research, Aarhus BSS, Department of Psychology and Behavioural Sciences, Bartholins Allé 9, 8000 Aarhus C, Denmark
- Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Josep Call
- School of Psychology and Neuroscience, University of St Andrews, St Mary's Quad, South Street, St Andrews, Fife KY16 9JP, UK
- Max Planck Institute for Evolutionary Anthropology, Deutscher Platz 6, 04103 Leipzig, Germany
| | - Dorthe Berntsen
- Center on Autobiographical Memory Research, Aarhus BSS, Department of Psychology and Behavioural Sciences, Bartholins Allé 9, 8000 Aarhus C, Denmark
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30
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Kheifets A, Freestone D, Gallistel CR. Theoretical implications of quantitative properties of interval timing and probability estimation in mouse and rat. J Exp Anal Behav 2017; 108:39-72. [PMID: 28653484 PMCID: PMC5576873 DOI: 10.1002/jeab.261] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2016] [Accepted: 05/16/2017] [Indexed: 11/05/2022]
Abstract
In three experiments with mice ( Mus musculus ) and rats (Rattus norvigicus), we used a switch paradigm to measure quantitative properties of the interval-timing mechanism. We found that: 1) Rodents adjusted the precision of their timed switches in response to changes in the interval between the short and long feed latencies (the temporal goalposts). 2) The variability in the timing of the switch response was reduced or unchanged in the face of large trial-to-trial random variability in the short and long feed latencies. 3) The adjustment in the distribution of switch latencies in response to changes in the relative frequency of short and long trials was sensitive to the asymmetry in the Kullback-Leibler divergence. The three results suggest that durations are represented with adjustable precision, that they are timed by multiple timers, and that there is a trial-by-trial (episodic) record of feed latencies in memory.
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31
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Abstract
Source memory, or memory for the context in which a memory was formed, is a defining characteristic of human episodic memory and source memory errors are a debilitating symptom of memory dysfunction. Evidence for source memory in nonhuman primates is sparse despite considerable evidence for other types of sophisticated memory and the practical need for good models of episodic memory in nonhuman primates. A previous study showed that rhesus monkeys confused the identity of a monkey they saw with a monkey they heard, but only after an extended memory delay. This suggests that they initially remembered the source - visual or auditory - of the information but forgot the source as time passed. Here, we present a monkey model of source memory that is based on this previous study. In each trial, monkeys studied two images, one that they simply viewed and touched and the other that they classified as a bird, fish, flower, or person. In a subsequent memory test, they were required to select the image from one source but avoid the other. With training, monkeys learned to suppress responding to images from the to-be-avoided source. After longer memory intervals, monkeys continued to show reliable item memory, discriminating studied images from distractors, but made many source memory errors. Monkeys discriminated source based on study method, not study order, providing preliminary evidence that our manipulation of retention interval caused errors due to source forgetting instead of source confusion. Finally, some monkeys learned to select remembered images from either source on cue, showing that they did indeed remember both items and both sources. This paradigm potentially provides a new model to study a critical aspect of episodic memory in nonhuman primates.
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Affiliation(s)
- Benjamin M Basile
- Emory University and Yerkes National Primate Research Center, Atlanta, GA 30322, USA.
| | - Robert R Hampton
- Emory University and Yerkes National Primate Research Center, Atlanta, GA 30322, USA
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32
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Lewis A, Call J, Berntsen D. Distinctiveness enhances long-term event memory in non-human primates, irrespective of reinforcement. Am J Primatol 2017; 79. [DOI: 10.1002/ajp.22665] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Revised: 02/22/2017] [Accepted: 03/11/2017] [Indexed: 11/08/2022]
Affiliation(s)
- Amy Lewis
- School of Psychology and Neuroscience; University of St Andrews, St Mary's Quad; St Andrews, Fife UK
- Max Planck Institute for Evolutionary Anthropology; Leipzig Germany
- Center on Autobiographical Memory Research; Århus C Denmark
| | - Josep Call
- School of Psychology and Neuroscience; University of St Andrews, St Mary's Quad; St Andrews, Fife UK
- Max Planck Institute for Evolutionary Anthropology; Leipzig Germany
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Abstract
Episodic memory has been analyzed in a number of different ways in both philosophy and psychology, and most controversy has centered on its self-referential, 'autonoetic' character. Here, we offer a comprehensive characterization of episodic memory in representational terms, and propose a novel functional account on this basis. We argue that episodic memory should be understood as a distinctive epistemic attitude taken towards an event simulation. On this view, episodic memory has a metarepresentational format and should not be equated with beliefs about the past. Instead, empirical findings suggest that the contents of human episodic memory are often constructed in the service of the explicit justification of such beliefs. Existing accounts of episodic memory function that have focused on explaining its constructive character through its role in 'future-oriented mental time travel' neither do justice to its capacity to ground veridical beliefs about the past nor to its representational format. We provide an account of the metarepresentational structure of episodic memory in terms of its role in communicative interaction. The generative nature of recollection allows us to represent and communicate the reasons for why we hold certain beliefs about the past. In this process, autonoesis corresponds to the capacity to determine when and how to assert epistemic authority in making claims about the past. A domain where such claims are indispensable are human social engagements. Such engagements commonly require the justification of entitlements and obligations, which is often possible only by explicit reference to specific past events.
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Affiliation(s)
- Johannes Mahr
- Department of Cognitive Science,Cognitive Development Center,Central European University,Budapest,Hungary
| | - Gergely Csibra
- Department of Cognitive Science,Cognitive Development Center,Central European University,Budapest,Hungary
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34
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Preconditioning of Spatial and Auditory Cues: Roles of the Hippocampus, Frontal Cortex, and Cue-Directed Attention. Brain Sci 2016; 6:brainsci6040063. [PMID: 27999366 PMCID: PMC5187577 DOI: 10.3390/brainsci6040063] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Revised: 12/07/2016] [Accepted: 12/16/2016] [Indexed: 11/18/2022] Open
Abstract
Loss of function of the hippocampus or frontal cortex is associated with reduced performance on memory tasks, in which subjects are incidentally exposed to cues at specific places in the environment and are subsequently asked to recollect the location at which the cue was experienced. Here, we examined the roles of the rodent hippocampus and frontal cortex in cue-directed attention during encoding of memory for the location of a single incidentally experienced cue. During a spatial sensory preconditioning task, rats explored an elevated platform while an auditory cue was incidentally presented at one corner. The opposite corner acted as an unpaired control location. The rats demonstrated recollection of location by avoiding the paired corner after the auditory cue was in turn paired with shock. Damage to either the dorsal hippocampus or the frontal cortex impaired this memory ability. However, we also found that hippocampal lesions enhanced attention directed towards the cue during the encoding phase, while frontal cortical lesions reduced cue-directed attention. These results suggest that the deficit in spatial sensory preconditioning caused by frontal cortical damage may be mediated by inattention to the location of cues during the latent encoding phase, while deficits following hippocampal damage must be related to other mechanisms such as generation of neural plasticity.
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Smith AE, Slivicki RA, Hohmann AG, Crystal JD. The chemotherapeutic agent paclitaxel selectively impairs learning while sparing source memory and spatial memory. Behav Brain Res 2016; 320:48-57. [PMID: 27908748 DOI: 10.1016/j.bbr.2016.11.042] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 11/22/2016] [Accepted: 11/25/2016] [Indexed: 11/15/2022]
Abstract
Chemotherapeutic agents are widely used to treat patients with systemic cancer. The efficacy of these therapies is undermined by their adverse side-effect profiles such as cognitive deficits that have a negative impact on the quality of life of cancer survivors. Cognitive side effects occur across a variety of domains, including memory, executive function, and processing speed. Such impairments are exacerbated under cognitive challenges and a subgroup of patients experience long-term impairments. Episodic memory in rats can be examined using a source memory task. In the current study, rats received paclitaxel, a taxane-derived chemotherapeutic agent, and learning and memory functioning was examined using the source memory task. Treatment with paclitaxel did not impair spatial and episodic memory, and paclitaxel treated rats were not more susceptible to cognitive challenges. Under conditions in which memory was not impaired, paclitaxel treatment impaired learning of new rules, documenting a decreased sensitivity to changes in experimental contingencies. These findings provide new information on the nature of cancer chemotherapy-induced cognitive impairments, particularly regarding the incongruent vulnerability of episodic memory and new learning following treatment with paclitaxel.
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Affiliation(s)
- Alexandra E Smith
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Richard A Slivicki
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States
| | - Andrea G Hohmann
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States; Gill Center for Biomolecular Science, Indiana University, Bloomington, IN, United States
| | - Jonathon D Crystal
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, United States.
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Smith AE, Dalecki SJ, Crystal JD. A test of the reward-value hypothesis. Anim Cogn 2016; 20:215-220. [PMID: 27709367 DOI: 10.1007/s10071-016-1040-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Revised: 09/20/2016] [Accepted: 09/27/2016] [Indexed: 11/26/2022]
Abstract
Rats retain source memory (memory for the origin of information) over a retention interval of at least 1 week, whereas their spatial working memory (radial maze locations) decays within approximately 1 day. We have argued that different forgetting functions dissociate memory systems. However, the two tasks, in our previous work, used different reward values. The source memory task used multiple pellets of a preferred food flavor (chocolate), whereas the spatial working memory task provided access to a single pellet of standard chow-flavored food at each location. Thus, according to the reward-value hypothesis, enhanced performance in the source memory task stems from enhanced encoding/memory of a preferred reward. We tested the reward-value hypothesis by using a standard 8-arm radial maze task to compare spatial working memory accuracy of rats rewarded with either multiple chocolate or chow pellets at each location using a between-subjects design. The reward-value hypothesis predicts superior accuracy for high-valued rewards. We documented equivalent spatial memory accuracy for high- and low-value rewards. Importantly, a 24-h retention interval produced equivalent spatial working memory accuracy for both flavors. These data are inconsistent with the reward-value hypothesis and suggest that reward value does not explain our earlier findings that source memory survives unusually long retention intervals.
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Affiliation(s)
- Alexandra E Smith
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405-7007, USA
| | - Stefan J Dalecki
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405-7007, USA
| | - Jonathon D Crystal
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, 47405-7007, USA.
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Source memory in rats is impaired by an NMDA receptor antagonist but not by PSD95-nNOS protein-protein interaction inhibitors. Behav Brain Res 2016; 305:23-9. [PMID: 26909849 DOI: 10.1016/j.bbr.2016.02.021] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 02/16/2016] [Accepted: 02/18/2016] [Indexed: 12/23/2022]
Abstract
Limitations of preclinical models of human memory contribute to the pervasive view that rodent models do not adequately predict therapeutic efficacy in producing cognitive impairments or improvements in humans. We used a source-memory model (i.e., a representation of the origin of information) we developed for use in rats to evaluate possible drug-induced impairments of both spatial memory and higher order memory functions in the same task. Memory impairment represents a major barrier to use of NMDAR antagonists as pharmacotherapies. The scaffolding protein postsynaptic density 95kDa (PSD95) links NMDARs to the neuronal enzyme nitric oxide synthase (nNOS), which catalyzes production of the signaling molecule nitric oxide (NO). Therefore, interrupting PSD95-nNOS protein-protein interactions downstream of NMDARs represents a novel therapeutic strategy to interrupt NMDAR-dependent NO signaling while bypassing unwanted side effects of NMDAR antagonists. We hypothesized that the NMDAR antagonist MK-801 would impair source memory. We also hypothesized that PSD95-nNOS inhibitors (IC87201 and ZL006) would lack the profile of cognitive impairment associated with global NMDAR antagonists. IC87201 and ZL006 suppressed NMDA-stimulated formation of cGMP, a marker of NO production, in cultured hippocampal neurons. MK-801, at doses that did not impair motor function, impaired source memory under conditions in which spatial memory was spared. Thus, source memory was more vulnerable than spatial memory to impairment. By contrast, PSD95-nNOS inhibitors, IC87201 and ZL006, administered at doses that are behaviorally effective in rats, spared source memory, spatial memory, and motor function. Thus, PSD95-nNOS inhibitors are likely to exhibit favorable therapeutic ratios compared to NMDAR antagonists.
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Bratch A, Kann S, Cain JA, Wu JE, Rivera-Reyes N, Dalecki S, Arman D, Dunn A, Cooper S, Corbin HE, Doyle AR, Pizzo MJ, Smith AE, Crystal JD. Working Memory Systems in the Rat. Curr Biol 2016; 26:351-5. [PMID: 26776732 DOI: 10.1016/j.cub.2015.11.068] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Revised: 11/19/2015] [Accepted: 11/30/2015] [Indexed: 11/29/2022]
Abstract
A fundamental feature of memory in humans is the ability to simultaneously work with multiple types of information using independent memory systems. Working memory is conceptualized as two independent memory systems under executive control [1, 2]. Although there is a long history of using the term "working memory" to describe short-term memory in animals, it is not known whether multiple, independent memory systems exist in nonhumans. Here, we used two established short-term memory approaches to test the hypothesis that spatial and olfactory memory operate as independent working memory resources in the rat. In the olfactory memory task, rats chose a novel odor from a gradually incrementing set of old odors [3]. In the spatial memory task, rats searched for a depleting food source at multiple locations [4]. We presented rats with information to hold in memory in one domain (e.g., olfactory) while adding a memory load in the other domain (e.g., spatial). Control conditions equated the retention interval delay without adding a second memory load. In a further experiment, we used proactive interference [5-7] in the spatial domain to compromise spatial memory and evaluated the impact of adding an olfactory memory load. Olfactory and spatial memory are resistant to interference from the addition of a memory load in the other domain. Our data suggest that olfactory and spatial memory draw on independent working memory systems in the rat.
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Affiliation(s)
- Alexander Bratch
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Spencer Kann
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Joshua A Cain
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Jie-En Wu
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Nilda Rivera-Reyes
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Stefan Dalecki
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Diana Arman
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Austin Dunn
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Shiloh Cooper
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Hannah E Corbin
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Amanda R Doyle
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Matthew J Pizzo
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Alexandra E Smith
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA
| | - Jonathon D Crystal
- Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN 47405-7007, USA.
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Crystal JD. Animal models of source memory. J Exp Anal Behav 2015; 105:56-67. [PMID: 26609644 DOI: 10.1002/jeab.173] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2015] [Accepted: 11/02/2015] [Indexed: 11/09/2022]
Abstract
Source memory is the aspect of episodic memory that encodes the origin (i.e., source) of information acquired in the past. Episodic memory (i.e., our memories for unique personal past events) typically involves source memory because those memories focus on the origin of previous events. Source memory is at work when, for example, someone tells a favorite joke to a person while avoiding retelling the joke to the friend who originally shared the joke. Importantly, source memory permits differentiation of one episodic memory from another because source memory includes features that were present when the different memories were formed. This article reviews recent efforts to develop an animal model of source memory using rats. Experiments are reviewed which suggest that source memory is dissociated from other forms of memory. The review highlights strengths and weaknesses of a number of animal models of episodic memory. Animal models of source memory may be used to probe the biological bases of memory. Moreover, these models can be combined with genetic models of Alzheimer's disease to evaluate pharmacotherapies that ultimately have the potential to improve memory.
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Numan R. A Prefrontal-Hippocampal Comparator for Goal-Directed Behavior: The Intentional Self and Episodic Memory. Front Behav Neurosci 2015; 9:323. [PMID: 26635567 PMCID: PMC4658443 DOI: 10.3389/fnbeh.2015.00323] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 11/11/2015] [Indexed: 01/02/2023] Open
Abstract
The hypothesis of this article is that the interactions between the prefrontal cortex and the hippocampus play a critical role in the modulation of goal-directed self-action and the strengthening of episodic memories. We describe various theories that model a comparator function for the hippocampus, and then elaborate the empirical evidence that supports these theories. One theory which describes a prefrontal-hippocampal comparator for voluntary action is emphasized. Action plans are essential for successful goal-directed behavior, and are elaborated by the prefrontal cortex. When an action plan is initiated, the prefrontal cortex transmits an efference copy (or corollary discharge) to the hippocampus where it is stored as a working memory for the action plan (which includes the expected outcomes of the action plan). The hippocampus then serves as a response intention-response outcome working memory comparator. Hippocampal comparator function is enabled by the hippocampal theta rhythm allowing the hippocampus to compare expected action outcomes to actual action outcomes. If the expected and actual outcomes match, the hippocampus transmits a signal to prefrontal cortex which strengthens or consolidates the action plan. If a mismatch occurs, the hippocampus transmits an error signal to the prefrontal cortex which facilitates a reformulation of the action plan, fostering behavioral flexibility and memory updating. The corollary discharge provides the self-referential component to the episodic memory, affording the personal and subjective experience of what behavior was carried out, when it was carried out, and in what context (where) it occurred. Such a perspective can be applied to episodic memory in humans, and episodic-like memory in non-human animal species.
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Affiliation(s)
- Robert Numan
- Psychology Department, Santa Clara University Santa Clara, CA, USA
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41
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Basile BM. Rats remind us what actually counts in episodic memory research. Front Psychol 2015; 6:75. [PMID: 25699000 PMCID: PMC4316706 DOI: 10.3389/fpsyg.2015.00075] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2015] [Accepted: 01/14/2015] [Indexed: 11/13/2022] Open
Affiliation(s)
- Benjamin M Basile
- Section on the Neurobiology of Learning and Memory, Laboratory of Neuropsychology, National Institute of Mental Health, National Institutes of Health Bethesda, MD, USA
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42
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Binding of episodic memories in the rat. Curr Biol 2014; 24:2957-61. [PMID: 25466681 DOI: 10.1016/j.cub.2014.10.074] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2014] [Revised: 10/16/2014] [Accepted: 10/29/2014] [Indexed: 11/22/2022]
Abstract
People remember an event as a coherent scene. Memory of such an episode is thought to reflect binding of a fully integrated representation, rather than memory of unconnected features. However, it is not known whether rodents form bound representations. Here we show that rats remember episodes as bound representations. Rats were presented with multiple features of unique episodes at memory encoding: what (food flavor), where (maze location), source (self-generated food seeking—running to the food site—or experimenter-generated food seeking—placement by the experimenter at the food site), and context (spatial cues in the room where the event occurred). After a delay, the trial continued with a memory assessment in which one flavor replenished at the self-generated—but not at experimenter-generated—locations. We presented rats with multiple overlapping features, in rapid succession, to ensure that successful memory retrieval required them to disambiguate multiple study episodes (using two rooms). We found that binding is resistant to interference from highly similar episodes and survives long retention intervals (∼1 week). Our results suggest that multiple episodic memories are each structured as bound representations, which suggests that nonhumans represent episodic memories using a structure similar to that of people. This finding enhances the translational potential for utilizing animal models of episodic memory to explore the biological mechanisms of memory and validate therapeutic approaches for treating disorders of memory.
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Abstract
Episodic memories differ from other types of memory because they represent aspects of the past not present in other memories, such as the time, place, or social context in which the memories were formed. Focus on phenomenal experience in human memory, such as the sense of 'having been there', has resulted in conceptualizations of episodic memory that are difficult or impossible to apply to nonhuman species. It is therefore a significant challenge for investigators to agree on objective behavioral criteria that can be applied in nonhuman animals and still capture features of memory thought to be critical in humans. Some investigators have attempted to use neurobiological parallels to bridge this gap; however, defining memory types on the basis of the brain structures involved rather than on identified cognitive mechanisms risks missing crucial functional aspects of episodic memory, which are ultimately behavioral. The most productive way forward is likely a combination of neurobiology and sophisticated cognitive testing that identifies the mental representations present in episodic memory. Investigators that have refined their approach from asking the naïve question "do nonhuman animals have episodic memory" to instead asking "what aspects of episodic memory are shared by humans and nonhumans" are making progress.
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Affiliation(s)
- Victoria L Templer
- Department of Psychology, Emory University, 36 Eagle Row, Atlanta, GA 30322, USA.
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Dissociable memory traces within the macaque medial temporal lobe predict subsequent recognition performance. J Neurosci 2014; 34:1988-97. [PMID: 24478378 DOI: 10.1523/jneurosci.4048-13.2014] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Functional magnetic resonance imaging (fMRI) studies have revealed that activity in the medial temporal lobe (MTL) predicts subsequent memory performance in humans. Because of limited knowledge on cytoarchitecture and axonal projections of the human MTL, precise localization and characterization of the areas that can predict subsequent memory performance are benefited by the use of nonhuman primates in which integrated approach of the MRI- and cytoarchiture-based boundary delineation is available. However, neural correlates of this subsequent memory effect have not yet been identified in monkeys. Here, we used fMRI to examine activity in the MTL during memory encoding of events that monkeys later remembered or forgot. Application of both multivoxel pattern analysis and conventional univariate analysis to high-resolution fMRI data allowed us to identify memory traces within the caudal entorhinal cortex (cERC) and perirhinal cortex (PRC), as well as within the hippocampus proper. Furthermore, activity in the cERC and the hippocampus, which are directly connected, was responsible for encoding the initial items of sequentially presented pictures, which may reflect recollection-like recognition, whereas activity in the PRC was not. These results suggest that two qualitatively distinct encoding processes work in the monkey MTL and that recollection-based memory is formed by the interplay of the hippocampus with the cERC, a focal cortical area anatomically closer to the hippocampus and hierarchically higher than previously believed. These findings will advance the understanding of common memory system between humans and monkeys and accelerate fine electrophysiological characterization of these dissociable memory traces in the monkey MTL.
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Abstract
Source memory represents the origin (source) of information. Recently, we proposed that rats (Rattus norvegicus) remember the source of information. However, an alternative to source memory is the possibility that rats selectively encoded some, but not all, information rather than retrieving an episodic memory. We directly tested this 'encoding failure' hypothesis. Here, we show that rats remember the source of information, under conditions that cannot be attributed to encoding failure. Moreover, source memory lasted at least seven days but was no longer present 14 days after studying. Our findings suggest that long-lasting source memory may be modelled in non-humans. Our model should facilitate attempts to elucidate the biological underpinnings of source memory impairments in human memory disorders such as Alzheimer's disease.
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Affiliation(s)
- Jonathon D Crystal
- Department of Psychological and Brain Sciences, Indiana University, , Bloomington, IN 47405-7007, USA
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46
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Abstract
A recent study using a novel procedure to test the memory of rats for a preferred (chocolate) reinforcement shows many key characteristics that define source memory and episodic memory in humans.
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47
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Martin-Ordas G, Berntsen D, Call J. Memory for distant past events in chimpanzees and orangutans. Curr Biol 2013; 23:1438-41. [PMID: 23871242 DOI: 10.1016/j.cub.2013.06.017] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2012] [Revised: 05/21/2013] [Accepted: 06/06/2013] [Indexed: 11/25/2022]
Abstract
Determining the memory systems that support nonhuman animals' capacity to remember distant past events is currently the focus an intense research effort and a lively debate [1-3]. Comparative psychology has largely adopted Tulving's framework by focusing on whether animals remember what-where-when something happened (i.e., episodic-like memory) [4-6]. However, apes have also been reported to recall other episodic components [7] after single-trial exposures [8, 9]. Using a new experimental paradigm we show that chimpanzees and orangutans recalled a tool-finding event that happened four times 3 years earlier (experiment 1) and a tool-finding unique event that happened once 2 weeks earlier (experiment 2). Subjects were able to distinguish these events from other tool-finding events, which indicates binding of relevant temporal-spatial components. Like in human involuntary autobiographical memory, a cued, associative retrieval process triggered apes' memories: when presented with a particular setup, subjects instantaneously remembered not only where to search for the tools (experiment 1), but also the location of the tool seen only once (experiment 2). The complex nature of the events retrieved, the unexpected and fast retrieval, the long retention intervals involved, and the detection of binding strongly suggest that chimpanzees and orangutans' memories for past events mirror some of the features of human autobiographical memory.
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Affiliation(s)
- Gema Martin-Ordas
- Center on Autobiographical Memory Research, Aarhus University, 8000 Aarhus C, Denmark.
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Martin-Ordas G, Call J. Episodic memory: a comparative approach. Front Behav Neurosci 2013; 7:63. [PMID: 23781179 PMCID: PMC3678104 DOI: 10.3389/fnbeh.2013.00063] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2013] [Accepted: 05/22/2013] [Indexed: 11/17/2022] Open
Abstract
Historically, episodic memory has been described as autonoetic, personally relevant, complex, context-rich, and allowing mental time travel. In contrast, semantic memory, which is theorized to be free of context and personal relevance, is noetic and consists of general knowledge of facts about the world. The field of comparative psychology has adopted this distinction in order to study episodic memory in non-human animals. Our aim in this article is not only to reflect on the concept of episodic memory and the experimental approaches used in comparative psychology to study this phenomenon, but also to provide a critical analysis of these paradigms. We conclude the article by providing new avenues for future research.
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Affiliation(s)
- Gema Martin-Ordas
- Center on Autobiographical Memory Research, Aarhus University, Aarhus, Denmark
| | - Josep Call
- Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany
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Motivational Neuroscience: Instant Desire for Something You Know Is Bad. Curr Biol 2013; 23:R239-41. [DOI: 10.1016/j.cub.2013.01.060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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