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Comino Garcia-Munoz A, Alemán-Gómez Y, Toledano R, Poch C, García-Morales I, Aledo-Serrano Á, Gil-Nagel A, Campo P. Morphometric and microstructural characteristics of hippocampal subfields in mesial temporal lobe epilepsy and their correlates with mnemonic discrimination. Front Neurol 2023; 14:1096873. [PMID: 36864916 PMCID: PMC9972498 DOI: 10.3389/fneur.2023.1096873] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2022] [Accepted: 01/18/2023] [Indexed: 02/16/2023] Open
Abstract
Introduction Pattern separation (PS) is a fundamental aspect of memory creation that defines the ability to transform similar memory representations into distinct ones, so they do not overlap when storing and retrieving them. Experimental evidence in animal models and the study of other human pathologies have demonstrated the role of the hippocampus in PS, in particular of the dentate gyrus (DG) and CA3. Patients with mesial temporal lobe epilepsy with hippocampal sclerosis (MTLE-HE) commonly report mnemonic deficits that have been associated with failures in PS. However, the link between these impairments and the integrity of the hippocampal subfields in these patients has not yet been determined. The aim of this work is to explore the association between the ability to perform mnemonic functions and the integrity of hippocampal CA1, CA3, and DG in patients with unilateral MTLE-HE. Method To reach this goal we evaluated the memory of patients with an improved object mnemonic similarity test. We then analyzed the hippocampal complex structural and microstructural integrity using diffusion weighted imaging. Results Our results indicate that patients with unilateral MTLE-HE present alterations in both volume and microstructural properties at the level of the hippocampal subfields DG, CA1, CA3, and the subiculum, that sometimes depend on the lateralization of their epileptic focus. However, none of the specific changes was found to be directly related to the performance of the patients in a pattern separation task, which might indicate a contribution of various alterations to the mnemonic deficits or the key contribution of other structures to the function. Discussion we established for the first time the alterations in both the volume and the microstructure at the level of the hippocampal subfields in a group of unilateral MTLE patients. We observed that these changes are greater in the DG and CA1 at the macrostructural level, and in CA3 and CA1 in the microstructural level. None of these changes had a direct relation to the performance of the patients in a pattern separation task, which suggests a contribution of various alterations to the loss of function.
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Affiliation(s)
- Alicia Comino Garcia-Munoz
- Centre de Résonance Magnétique Biologique et Médicale-Unité Mixte de Recherche 7339, Aix-Marseille Université, Marseille, France
| | - Yasser Alemán-Gómez
- Connectomics Lab, Lausanne University Hospital (CHUV), Lausanne, Switzerland
| | - Rafael Toledano
- Epilepsy Unit, Neurology Department, Hospital Ruber Internacional, Madrid, Spain,Epilepsy Unit, Neurology Department, University Hospital Ramón y Cajal, Madrid, Spain
| | - Claudia Poch
- Facultad de Lenguas y Educación, Universidad de Nebrija, Madrid, Spain
| | - Irene García-Morales
- Epilepsy Unit, Neurology Department, Hospital Ruber Internacional, Madrid, Spain,Epilepsy Unit, Neurology Department, University Hospital of San Carlos, Madrid, Spain
| | - Ángel Aledo-Serrano
- Epilepsy Unit, Neurology Department, Hospital Ruber Internacional, Madrid, Spain
| | - Antonio Gil-Nagel
- Epilepsy Unit, Neurology Department, Hospital Ruber Internacional, Madrid, Spain
| | - Pablo Campo
- Department of Basic Psychology, Autonoma University of Madrid, Madrid, Spain,*Correspondence: Pablo Campo ✉
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De Simone MS, Lombardi MG, De Tollis M, Perri R, Fadda L, Caltagirone C, Carlesimo GA. Forgetting rate for the familiarity and recollection components of recognition in amnestic mild cognitive impairment: A longitudinal study. APPLIED NEUROPSYCHOLOGY. ADULT 2022:1-13. [PMID: 36264763 DOI: 10.1080/23279095.2022.2135441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Here we aimed to investigate the rate of forgetting of the familiarity and recollection components of recognition in patients at the onset of medial temporal lobe (MTL) pathology and destined to convert to Alzheimer's disease (AD). For this purpose, we conducted a longitudinal study of 13 patients who were diagnosed with amnestic mild cognitive impairment (a-MCI) at the first assessment and followed-up for 3 years. During this time, five patients converted to AD and eight remained in a stable condition of cognitive impairment. A group of 15 healthy subjects were enrolled as the control group (HC). In order to separately quantify the contribution of recollection and familiarity to recognition memory performance, the experimental sample was submitted to a modified version of Huppert and Piercy's procedure that included a Remember/Know paradigm. Data demonstrated that both stable and converter a-MCI patients forgot memory traces relative to the familiarity components of recognition at the same rate as HC. Conversely, converter a-MCI patients showed accelerated long-term forgetting specifically for the recollection component of recognition compared to stable a-MCI and HC. This is the first empirical demonstration that familiarity and recollection components of declarative memory are subject to different rates of forgetting in a-MCI patients as a function of their longitudinal clinical outcome. Our finding of accelerated long-term forgetting of the recollection component of recognition disclosed by converter a-MCI patients suggests that atrophy in the MTL not only interferes with the storage aspects but also disrupts the consolidation of memory traces.
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Affiliation(s)
- Maria Stefania De Simone
- Laboratory of Neuropsychology of Memory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Maria Giovanna Lombardi
- Laboratory of Neuropsychology of Memory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Massimo De Tollis
- Technology and Training Methods for Disability Care Laboratory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Roberta Perri
- Laboratory of Neuropsychology of Memory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Lucia Fadda
- Laboratory of Neuropsychology of Memory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
- Department of Systems Medicine, Tor Vergata University, Rome, Italy
| | - Carlo Caltagirone
- Laboratory of Neuropsychology of Memory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
- Technology and Training Methods for Disability Care Laboratory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
| | - Giovanni Augusto Carlesimo
- Laboratory of Neuropsychology of Memory, Department of Clinical and Behavioral Neurology, IRCCS Santa Lucia Foundation, Rome, Italy
- Department of Systems Medicine, Tor Vergata University, Rome, Italy
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García-Rueda L, Poch C, Campo P. Forgetting Details in Visual Long-Term Memory: Decay or Interference? Front Behav Neurosci 2022; 16:887321. [PMID: 35928790 PMCID: PMC9345118 DOI: 10.3389/fnbeh.2022.887321] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2022] [Accepted: 06/15/2022] [Indexed: 11/20/2022] Open
Abstract
Two main explanations for memory loss have been proposed. On the one hand, decay theories consider that over time memory fades away. On the other hand, interference theories sustain that when similar memories are encoded, they become more prone to confusion. The interference is greater as the degree of similarity between memories increases, and as the number of similar traces increases too. To reduce interference, the pattern separation process allows the brain to separate similar memories and build detailed memory representations that are less easily confused. Nonetheless, with time, we tend to remember more general aspects of experiences, which also affects our ability to discriminate. We present the results of one experiment in which brain activity was recorded by EEG while two groups of healthy participants performed a visual memory discrimination task. This task assesses the ability to differentiate new but similar information from previously learned information and thus avoid interference. Unlike previous studies, we used a paradigm that was specifically designed to assess the impact of the number of items (2 or 6) of each category stored in memory, as well as the time elapsed after the study phase (20 min or 24 h), on recognition memory for objects. Behaviorally, our results suggest that mnemonic discrimination is not modulated by the passage of time, but by the number of stored events. ERP results show a reduced amplitude in posterior regions between 500 and 700 ms when comparing short and long delays. We also observe a more positive activity in a centro-posterior region in the 500–700 ms window at retrieval when participants store more items. Interestingly, amplitudes for old hits and similar false alarms were greater than amplitudes for correctly rejected new items between 500 and 700 ms. This finding indicates that a recollection-based process operates in both true and false recognition. We also found that the waveforms for correct rejections of similar lures and the waveforms for correct rejections of new items were comparable.
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Affiliation(s)
- Laura García-Rueda
- Departamento de Anatomía, Histología y Neurociencia, Universidad Autónoma de Madrid, Madrid, Spain
| | - Claudia Poch
- Facultad de Lenguas y Educación, Universidad de Nebrija, Madrid, Spain
| | - Pablo Campo
- Department of Basic Psychology, Universidad Autónoma de Madrid, Madrid, Spain
- *Correspondence: Pablo Campo
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Lalani SJ, Reyes A, Kaestner E, Stark SM, Stark CEL, Lee D, Kansal L, Shih JJ, Smith CN, Paul BM, McDonald CR. Impaired Behavioral Pattern Separation in Refractory Temporal Lobe Epilepsy and Mild Cognitive Impairment. J Int Neuropsychol Soc 2022; 28:550-562. [PMID: 34078506 PMCID: PMC8965747 DOI: 10.1017/s1355617721000734] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
OBJECTIVE Episodic memory impairment and hippocampal pathology are hallmark features of both temporal lobe epilepsy (TLE) and amnestic mild cognitive impairment (aMCI). Pattern separation (PS), which enables the distinction between similar but unique experiences, is thought to contribute to successful encoding and retrieval of episodic memories. Impaired PS has been proposed as a potential mechanism underling episodic memory impairment in aMCI, but this association is less established in TLE. In this study, we examined behavioral PS in patients with TLE and explored whether profiles of performance in TLE are similar to aMCI. METHOD Patients with TLE, aMCI, and age-matched, healthy controls (HCs) completed a modified recognition task that relies on PS for the discrimination of highly similar lure items, the Mnemonic Similarity Task (MST). Group differences were evaluated and relationships between clinical characteristics, California Verbal Learning Test-Second Edition scores, and MST performance were tested in the TLE group. RESULTS Patients with TLE and aMCI demonstrated poorer PS performance relative to the HCs, but performance did not differ between the two patient groups. Neither the side of seizure focus nor having hippocampal sclerosis affected performance in TLE. However, TLE patients with clinically defined memory impairment showed the poorest performance. CONCLUSION Memory performance on a task that relies on PS was disrupted to a similar extent in TLE and aMCI. The MST could provide a clinically useful tool for measuring hippocampus-dependent memory impairments in TLE and other neurological disorders associated with hippocampal damage.
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Affiliation(s)
- Sanam J Lalani
- Department of Neurology, University of California San Francisco, San Francisco, CA, USA
| | - Anny Reyes
- San Diego State University, University of California San Diego Joint Doctoral Program in Clinical Psychology, San Diego, CA, USA
- Center for Multimodal Imaging and Genetics, University of California, San Diego, CA, USA
- Department of Psychiatry, University of California, San Diego, CA, USA
| | - Erik Kaestner
- Center for Multimodal Imaging and Genetics, University of California, San Diego, CA, USA
- Department of Psychiatry, University of California, San Diego, CA, USA
| | - Shauna M Stark
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA, USA
| | - Craig E L Stark
- Department of Neurobiology and Behavior, University of California Irvine, Irvine, CA, USA
| | - David Lee
- Department of Neurosciences, University of California San Diego, San Diego, CA, USA
| | - Leena Kansal
- Department of Neurosciences, University of California San Diego, San Diego, CA, USA
| | - Jerry J Shih
- Department of Neurosciences, University of California San Diego, San Diego, CA, USA
| | - Christine N Smith
- Department of Psychiatry, University of California, San Diego, CA, USA
- Veterans Affairs San Diego Healthcare System, San Diego, CA, USA
- Center for the Neurobiology of Learning and Memory, University of California, Irvine, Irvine, CA, USA
| | - Brianna M Paul
- Department of Neurology, University of California San Francisco, San Francisco, CA, USA
| | - Carrie R McDonald
- San Diego State University, University of California San Diego Joint Doctoral Program in Clinical Psychology, San Diego, CA, USA
- Center for Multimodal Imaging and Genetics, University of California, San Diego, CA, USA
- Department of Psychiatry, University of California, San Diego, CA, USA
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Dohm-Hansen S, Donoso F, Lucassen PJ, Clarke G, Nolan YM. The gut microbiome and adult hippocampal neurogenesis: A new focal point for epilepsy? Neurobiol Dis 2022; 170:105746. [DOI: 10.1016/j.nbd.2022.105746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2021] [Revised: 04/13/2022] [Accepted: 04/29/2022] [Indexed: 02/07/2023] Open
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Deficits in Behavioral and Neuronal Pattern Separation in Temporal Lobe Epilepsy. J Neurosci 2021; 41:9669-9686. [PMID: 34620720 PMCID: PMC8612476 DOI: 10.1523/jneurosci.2439-20.2021] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Revised: 09/09/2021] [Accepted: 09/21/2021] [Indexed: 11/21/2022] Open
Abstract
In temporal lobe epilepsy, the ability of the dentate gyrus to limit excitatory cortical input to the hippocampus breaks down, leading to seizures. The dentate gyrus is also thought to help discriminate between similar memories by performing pattern separation, but whether epilepsy leads to a breakdown in this neural computation, and thus to mnemonic discrimination impairments, remains unknown. Here we show that temporal lobe epilepsy is characterized by behavioral deficits in mnemonic discrimination tasks, in both humans (females and males) and mice (C57Bl6 males, systemic low-dose kainate model). Using a recently developed assay in brain slices of the same epileptic mice, we reveal a decreased ability of the dentate gyrus to perform certain forms of pattern separation. This is because of a subset of granule cells with abnormal bursting that can develop independently of early EEG abnormalities. Overall, our results linking physiology, computation, and cognition in the same mice advance our understanding of episodic memory mechanisms and their dysfunction in epilepsy.SIGNIFICANCE STATEMENT People with temporal lobe epilepsy (TLE) often have learning and memory impairments, sometimes occurring earlier than the first seizure, but those symptoms and their biological underpinnings are poorly understood. We focused on the dentate gyrus, a brain region that is critical to avoid confusion between similar memories and is anatomically disorganized in TLE. We show that both humans and mice with TLE experience confusion between similar situations. This impairment coincides with a failure of the dentate gyrus to disambiguate similar input signals because of pathologic bursting in a subset of neurons. Our work bridges seizure-oriented and memory-oriented views of the dentate gyrus function, suggests a mechanism for cognitive symptoms in TLE, and supports a long-standing hypothesis of episodic memory theories.
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Bencze D, Szőllősi Á, Racsmány M. Learning to distinguish: shared perceptual features and discrimination practice tune behavioural pattern separation. Memory 2021; 29:605-621. [PMID: 33998372 DOI: 10.1080/09658211.2021.1924788] [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: 10/21/2022]
Abstract
Pattern separation is a computational mechanism performed by the hippocampus allowing the reduction of overlap between sensory inputs with similar perceptual features. Our first aim was to develop a new paradigm sensitive to the behavioural consequences of pattern separation (mnemonic discrimination). For this purpose, we constructed morphed face stimuli with parametrically changing levels of similarity. After encoding participants saw studied items and similar lure faces. Perceptual similarity affected false recognition and there was a gradual reduction in discrimination accuracy with the increment of similarity between the stimuli. However, confidence ratings were sensitive to smaller changes (Experiment 1) than the other test type with "old"/"similar"/"new" response options (Experiment 2). Mnemonic discrimination relies strongly on retrieving details of the original stimulus. Therefore, we investigated whether pattern separation can be tuned by retrieval in the form of a discrimination task (Experiment 3). Our findings suggest that repeatedly encountering the stimuli within a two-alternative forced-choice task (in comparison with the repeated presentation of the material) increased both the correct identification and the false recognition of similar stimuli two days after encoding. We conclude that basic computational mechanisms of the hippocampus can be tuned by a task that requires discrimination between studied and new stimuli.
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Affiliation(s)
- Dorottya Bencze
- Department of Cognitive Science, Budapest University of Technology and Economics, Budapest, Hungary.,Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Ágnes Szőllősi
- Department of Cognitive Science, Budapest University of Technology and Economics, Budapest, Hungary.,Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Budapest, Hungary
| | - Mihály Racsmány
- Department of Cognitive Science, Budapest University of Technology and Economics, Budapest, Hungary.,Institute of Cognitive Neuroscience and Psychology, Research Centre for Natural Sciences, Budapest, Hungary
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Keeler J, Lambert E, Olivola M, Owen J, Xia J, Thuret S, Himmerich H, Cardi V, Treasure J. Lower pattern recognition memory scores in anorexia nervosa. J Eat Disord 2021; 9:49. [PMID: 33865451 PMCID: PMC8052530 DOI: 10.1186/s40337-021-00406-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Accepted: 04/07/2021] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND There is extensive evidence for volumetric reductions in the hippocampus in patients with anorexia nervosa (AN), however the impact on function is unclear. Pattern separation and recognition are hippocampus-dependent forms of learning thought to underlie stimulus discrimination. METHODS The present study used the Mnemonic Similarity Task to investigate pattern separation and recognition for the first time in patients with AN (N = 46) and healthy controls (N = 56). An Analysis of Covariance examined between-group differences, controlling for age, antidepressant use and method of task delivery (remote vs. in person). RESULTS When controlling for covariates, pattern recognition memory scores were lower in the AN group with a medium effect size (d = 0.51). In contrast, there was a small effect whereby patients with AN had a greater pattern separation score than controls (d = 0.34), albeit this difference was not significant at the p = 0.05 threshold (p = 0.133). Furthermore, pattern separation and recognition memory abilities were not related to age, body mass index, eating disorder psychopathology or trait anxiety levels. CONCLUSIONS This preliminary study provides initial evidence for an imbalance in pattern separation and recognition abilities in AN, a hippocampus-dependent cognitive ability. Further studies should endeavour to investigate pattern separation and recognition performance further in AN, as well as investigate other hippocampus-dependent functions.
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Affiliation(s)
- Johanna Keeler
- Section of Eating Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, 103 Denmark Hill, London, SE5 8AF, UK.
| | - Ellen Lambert
- Section of Eating Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, 103 Denmark Hill, London, SE5 8AF, UK
| | - Miriam Olivola
- Section of Eating Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, 103 Denmark Hill, London, SE5 8AF, UK
- Department of Mental Health and Addictions, Azienda Socio-Sanitaria Territoriale di Pavia, Pavia, Italy
| | - Judith Owen
- Section of Eating Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, 103 Denmark Hill, London, SE5 8AF, UK
| | - Jingjing Xia
- Section of Eating Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, 103 Denmark Hill, London, SE5 8AF, UK
| | - Sandrine Thuret
- Department of Basic and Clinical Neuroscience, Institute of Psychiatry, Psychology and Neuroscience, King's College London, London, UK
- Department of Neurology, University Hospital Carl Gustav Carus, Technische Universität Dresden, Dresden, Germany
| | - Hubertus Himmerich
- Section of Eating Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, 103 Denmark Hill, London, SE5 8AF, UK
| | - Valentina Cardi
- Section of Eating Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, 103 Denmark Hill, London, SE5 8AF, UK
- Department of General Psychology, University of Padova, Padova, Italy
| | - Janet Treasure
- Section of Eating Disorders, Institute of Psychiatry, Psychology and Neuroscience, King's College London, 103 Denmark Hill, London, SE5 8AF, UK
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