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Şentürk YD, Ünver N, Demircan C, Egner T, Günseli E. The reactivation of task rules triggers the reactivation of task-relevant items. Cortex 2024; 171:465-480. [PMID: 38141571 DOI: 10.1016/j.cortex.2023.10.024] [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: 07/25/2023] [Accepted: 10/10/2023] [Indexed: 12/25/2023]
Abstract
Working memory (WM) describes the temporary storage of task-relevant items and procedural rules to guide action. Despite its central importance for goal-directed behavior, the interplay between WM and long-term memory (LTM) remains poorly understood. Recent studies have shown that repeated use of the same task-relevant item in WM results in a hand-off of the storage of that item to LTM, and switching to a new item reactivates WM. To further elucidate the rules governing WM-LTM interactions, we here planned to probe whether a change in task rules, independent of a switch in task-relevant items, would also lead to WM reactivation of maintained items. To this end, we used scalp-recorded electroencephalogram (EEG) data, specifically the contralateral delay activity (CDA), to track WM item storage while manipulating repetitions and changes in task rules and task-relevant items across trials in a visual WM task. We tested two rival hypotheses: If changes in task rules result in a reactivation of the target item representation, then the CDA should increase when a task change is cued even when the same target has been repeated across trials. However, if the reactivation of a task-relevant item only depends on the mnemonic availability of the item itself instead of the task it is used for, then only the changes in task-relevant items should reactivate the representations. Accordingly, the CDA amplitude should decrease for repeated task-relevant items independently of a task change. We found a larger CDA on task-switch compared to task-repeat trials, suggesting that the reactivation of task rules triggers the reactivation of task-relevant items in WM. By demonstrating that WM reactivation of LTM is interdependent for task rules and task-relevant items, this study informs our understanding of visual WM and its interplay with LTM. PREREGISTERED STAGE 1 PROTOCOL: https://osf.io/zp9e8 (date of in-principle acceptance: 19/12/2021).
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Affiliation(s)
- Yağmur D Şentürk
- Department of Psychology, Sabancı University, Istanbul, Türkiye.
| | - Nursima Ünver
- Department of Psychology, Sabancı University, Istanbul, Türkiye; Department of Psychology, University of Toronto, Canada.
| | - Can Demircan
- Department of Psychology, Sabancı University, Istanbul, Türkiye
| | - Tobias Egner
- Department of Psychology & Neuroscience, Duke University, Durham, NC, USA
| | - Eren Günseli
- Department of Psychology, Sabancı University, Istanbul, Türkiye
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2
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Slotnick SD. Does working memory activate the hippocampus during the late delay period? Cogn Neurosci 2022; 13:182-207. [PMID: 35699620 DOI: 10.1080/17588928.2022.2075842] [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: 11/03/2022]
Abstract
The aim of the present discussion paper was to identify whether any fMRI studies have provided convincing evidence that the hippocampus is associated with working memory. The key outcome variable was the phase in which hippocampal activity was observed: study, early delay, late delay, and/or test. During working memory tasks, long-term memory processes can operate during the study phase, early delay phase (due to extended encoding), or test phase. Thus, working memory processes can be isolated from long-term memory processes during only the late delay period. Twenty-six working memory studies that reported hippocampal activity were systematically analyzed. Many experimental protocols and analysis parameters were considered including number of participants, stimulus type(s), number of items during the study phase, delay duration, task during the test phase, behavioral accuracy, relevant fMRI contrast(s), whether the information was novel or familiar, number of phases modeled, and whether activation timecourses were extracted. For studies that were able to identify activity in different phases, familiar information sometimes produced activity during the study phase and/or test phase, but never produced activity during the delay period. When early-delay phase and late-delay phase activity could be distinguished via modeling these phases separately or inspecting activation timecourses, novel information could additionally produce activity during the early delay phase. There was no convincing evidence of hippocampal activity during the late delay period. These results indicate that working memory does not activate the hippocampus and suggest a model of working memory where maintenance of novel information can foster long-term memory encoding.
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Affiliation(s)
- Scott D Slotnick
- Department of Psychology and Neuroscience, Boston College Boston, MA, USA
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3
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Grot S, Leclerc ME, Luck D. Examining the neural correlates of active and passive forms of verbal-spatial binding in working memory. Biol Psychol 2018; 136:67-75. [PMID: 29802860 DOI: 10.1016/j.biopsycho.2018.05.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2017] [Revised: 03/15/2018] [Accepted: 05/17/2018] [Indexed: 11/29/2022]
Abstract
We designed an fMRI study to pinpoint the neural correlates of active and passive binding in working memory. Participants were instructed to memorize three words and three spatial locations. In the passive binding condition, words and spatial locations were directly presented as bound. Conversely, in the active binding condition, words and spatial locations were presented as separated, and participants were directed to intentionally create associations between them. Our results showed that participants performed better on passive binding relative to active binding. FMRI analysis revealed that both binding conditions induced greater activity within the hippocampus. Additionally, our analyses divulged regions specifically engaged in passive and active binding. Altogether, these data allow us to propose the hippocampus as a central candidate for working memory binding. When needed, a frontal-parietal network can contribute to the rearrangement of information. These findings may inform theories of working memory binding.
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Affiliation(s)
- Stéphanie Grot
- Centre de recherche, Institut universitaire en santé mentale de Montréal, Montreal, Canada; Department of Psychiatry, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - Marie-Eve Leclerc
- Centre de recherche, Institut universitaire en santé mentale de Montréal, Montreal, Canada; Department of Psychiatry, Faculty of Medicine, Université de Montréal, Montreal, Canada
| | - David Luck
- Centre de recherche, Institut universitaire en santé mentale de Montréal, Montreal, Canada; Department of Psychiatry, Faculty of Medicine, Université de Montréal, Montreal, Canada.
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4
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Bastin C. Differential age-related effects on conjunctive and relational visual short-term memory binding. Memory 2017; 26:1181-1190. [PMID: 29284344 DOI: 10.1080/09658211.2017.1421228] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
An age-related associative deficit has been described in visual short-term binding memory tasks. However, separate studies have suggested that ageing disrupts relational binding (to associate distinct items or item and context) more than conjunctive binding (to integrate features within an object). The current study directly compared relational and conjunctive binding with a short-term memory task for object-colour associations in 30 young and 30 older adults. Participants studied a number of object-colour associations corresponding to their individual object span level in a relational task in which objects were associated to colour patches and a conjunctive task where colour was integrated into the object. Memory for individual items and for associations was tested with a recognition memory test. Evidence for an age-related associative deficit was observed in the relational binding task, but not in the conjunctive binding task. This differential impact of ageing on relational and conjunctive short-term binding is discussed by reference to two underlying age-related cognitive difficulties: diminished hippocampally dependent binding and attentional resources.
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Affiliation(s)
- Christine Bastin
- a GIGA-Cyclotron Research Centre-in vivo imaging , Liège University , Liège , Belgium
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5
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Clark CA, Fernandez F, Sakhon S, Spanò G, Edgin JO. The medial temporal memory system in Down syndrome: Translating animal models of hippocampal compromise. Hippocampus 2017; 27:683-691. [PMID: 28346765 PMCID: PMC8109260 DOI: 10.1002/hipo.22724] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2016] [Revised: 09/06/2016] [Accepted: 03/07/2017] [Indexed: 01/19/2023]
Abstract
Recent studies have highlighted the dentate gyrus as a region of increased vulnerability in mouse models of Down syndrome (DS). It is unclear to what extent these findings are reflected in the memory profile of people with the condition. We developed a series of novel tasks to probe distinct medial temporal functions in children and young adults with DS, including object, spatial, and temporal order memory. Relative to mental age-matched controls (n = 45), individuals with DS (n = 28) were unimpaired on subtests involving short-term object or configural recall that was divorced from spatial or temporal contexts. By contrast, the DS group had difficulty recalling spatial locations when contextual information was salient and recalling the order in which objects were serially presented. Results are consistent with dysfunction of spatial and temporal contextual pattern separation abilities in individuals with DS, mediated by the hippocampus, including the dentate gyrus. Amidst increasing calls to bridge human and animal work, the memory profile demonstrated here in humans with DS is strikingly similar to that of the Ts65Dn mouse model of DS. The study highlights the trisynaptic circuit as a potentially fruitful intervention target to mitigate cognitive impairments associated with DS.
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Affiliation(s)
- Caron A.C. Clark
- Department of Psychology, Memory Development and Disorders Laboratory, University of Arizona, Tucson, Arizona
- Department of Educational Psychology, University of Nebraska, Lincoln, Nebraska
| | - Fabian Fernandez
- Department of Psychology, BIO5 and McKnight Brain Research Institutes, University of Arizona, Tucson, Arizona
- Department of Neurology, BIO5 and McKnight Brain Research Institutes, University of Arizona, Tucson, Arizona
| | - Stella Sakhon
- Department of Psychology, Memory Development and Disorders Laboratory, University of Arizona, Tucson, Arizona
| | - Goffredina Spanò
- Department of Psychology, Memory Development and Disorders Laboratory, University of Arizona, Tucson, Arizona
| | - Jamie O. Edgin
- Department of Psychology, Memory Development and Disorders Laboratory, University of Arizona, Tucson, Arizona
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Derrfuss J, Ekman M, Hanke M, Tittgemeyer M, Fiebach CJ. Distractor-resistant Short-Term Memory Is Supported by Transient Changes in Neural Stimulus Representations. J Cogn Neurosci 2017; 29:1547-1565. [PMID: 28430039 DOI: 10.1162/jocn_a_01141] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Goal-directed behavior in a complex world requires the maintenance of goal-relevant information despite multiple sources of distraction. However, the brain mechanisms underlying distractor-resistant working or short-term memory (STM) are not fully understood. Although early single-unit recordings in monkeys and fMRI studies in humans pointed to an involvement of lateral prefrontal cortices, more recent studies highlighted the importance of posterior cortices for the active maintenance of visual information also in the presence of distraction. Here, we used a delayed match-to-sample task and multivariate searchlight analyses of fMRI data to investigate STM maintenance across three extended delay phases. Participants maintained two samples (either faces or houses) across an unfilled pre-distractor delay, a distractor-filled delay, and an unfilled post-distractor delay. STM contents (faces vs. houses) could be decoded above-chance in all three delay phases from occipital, temporal, and posterior parietal areas. Classifiers trained to distinguish face versus house maintenance successfully generalized from pre- to post-distractor delays and vice versa, but not to the distractor delay period. Furthermore, classifier performance in all delay phases was correlated with behavioral performance in house, but not face, trials. Our results demonstrate the involvement of distributed posterior, but not lateral prefrontal, cortices in active maintenance during and after distraction. They also show that the neural code underlying STM maintenance is transiently changed in the presence of distractors and reinstated after distraction. The correlation with behavior suggests that active STM maintenance is particularly relevant in house trials, whereas face trials might rely more strongly on contributions from long-term memory.
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Affiliation(s)
- Jan Derrfuss
- Radboud University Nijmegen.,University of Nottingham
| | | | - Michael Hanke
- Otto von Guericke University, Magdeburg, Germany.,Center for Behavioral Brain Sciences, Magdeburg, Germany
| | | | - Christian J Fiebach
- Radboud University Nijmegen.,Goethe University Frankfurt.,Center for Individual Development and Adaptive Education, Frankfurt am Main, Germany
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7
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Gramunt N, Sánchez-Benavides G, Buschke H, Lipton RB, Masramon X, Gispert JD, Peña-Casanova J, Fauria K, Molinuevo JL. Psychometric Properties of the Memory Binding Test: Test-Retest Reliability and Convergent Validity. J Alzheimers Dis 2016; 50:999-1010. [PMID: 26836167 DOI: 10.3233/jad-150776] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
BACKGROUND Episodic memory testing is fundamental for the diagnosis of Alzheimer's disease (AD). Although the Free and Cued Selective Reminding Test (FCSRT) is widely used for this purpose, it may not be sensitive enough for early detection of subtle decline in preclinical AD. The Memory Binding Test (MBT) intends to overcome this limitation. OBJECTIVES To analyze the test-retest reliability of the MBT and its convergent validity with the FCRST. METHODS 36 cognitively healthy participants of the ALFA Study, aged 45 to 65, were included for the test-retest study and 69 for the convergent analysis. They were visited twice in a period of 6 ± 2 weeks. Test-retest reliability was determined by the calculation of the intra-class correlation coefficient (ICC). Score differences were studied by computing the mean percentage of score variation between visits and visualized by Bland-Altman plots. Convergent validity was determined by Pearson's correlations. RESULTS ICC values in the test-retest reliability analysis of the MBT direct scores ranged from 0.64 to 0.76. Subjects showed consistent practice effects, with mean amounts of score increasing between 10% and 26%. Pearson correlation between MBT and FCSRT direct scores showed r values between 0.40 and 0.53. The FCSRT displayed ceiling effects not observed in the MBT. CONCLUSIONS The MBT shows adequate test-retest reliability and overall moderate convergent validity with the FCSRT. Unlike the FCSRT, the MBT does not have ceiling effects and it may therefore be especially useful in longitudinal studies, facilitating the measurement of subtle memory performance decline and the detection of very early AD.
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Affiliation(s)
- Nina Gramunt
- Clinical Research Program, Barcelonaβeta Brain Research Center, Pasqual Maragall Foundation, Barcelona, Spain
| | - Gonzalo Sánchez-Benavides
- Clinical Research Program, Barcelonaβeta Brain Research Center, Pasqual Maragall Foundation, Barcelona, Spain
| | - Herman Buschke
- Department of Neurology, Albert Einstein College of Medicine. Bronx, NY, USA
| | - Richard B Lipton
- Department of Neurology, Albert Einstein College of Medicine. Bronx, NY, USA
| | | | - Juan D Gispert
- Clinical Research Program, Barcelonaβeta Brain Research Center, Pasqual Maragall Foundation, Barcelona, Spain
| | - Jordi Peña-Casanova
- Department of Behavioral Neurology, Service of Neurology, Hospital del Mar, Parc Salut Mar, Barcelona, Spain
| | - Karine Fauria
- Clinical Research Program, Barcelonaβeta Brain Research Center, Pasqual Maragall Foundation, Barcelona, Spain
| | - José L Molinuevo
- Clinical Research Program, Barcelonaβeta Brain Research Center, Pasqual Maragall Foundation, Barcelona, Spain
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8
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Bergmann HC, Daselaar SM, Fernández G, Kessels RPC. Neural substrates of successful working memory and long-term memory formation in a relational spatial memory task. Cogn Process 2016; 17:377-387. [PMID: 27350001 PMCID: PMC5075341 DOI: 10.1007/s10339-016-0772-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Accepted: 06/15/2016] [Indexed: 11/27/2022]
Abstract
Working memory (WM) tasks may involve brain activation actually implicated in long-term memory (LTM). In order to disentangle these two memory systems, we employed a combined WM/LTM task, using a spatial relational (object-location) memory paradigm and analyzed which brain areas were associated with successful performance for either task using fMRI. Critically, we corrected for the performance on the respective memory task when analyzing subsequent memory effects. The WM task consisted of a delayed-match-to-sample task assessed in an MRI scanner. Each trial consisted of an indoor or outdoor scene in which the exact configuration of four objects had to be remembered. After a short delay (7–13 s), the scene was presented from a different angle and spatial recognition for two objects was tested. After scanning, participants received an unexpected subsequent recognition memory (LTM) task, where the two previously unprobed objects were tested. Brain activity during encoding, delay phase and probe phase was analyzed based on WM and LTM performance. Results showed that successful WM performance, when corrected for LTM performance, was associated with greater activation in the inferior frontal gyrus and left fusiform gyrus during the early stage of the maintenance phase. A correct decision during the WM probe was accompanied by greater activation in a wide network, including bilateral hippocampus, right superior parietal gyrus and bilateral insula. No voxels exhibited supra-threshold activity during the encoding phase, and we did not find any differential activity for correct versus incorrect trials in the WM task when comparing LTM correct versus LTM incorrect trials.
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Affiliation(s)
- Heiko C Bergmann
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Sander M Daselaar
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
| | - Guillén Fernández
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands
- Department of Cognitive Neuroscience, Radboud University Medical Center, Nijmegen, The Netherlands
| | - Roy P C Kessels
- Donders Institute for Brain, Cognition and Behaviour, Radboud University, Nijmegen, The Netherlands.
- Department of Medical Psychology, Radboud University Medical Center, Nijmegen, The Netherlands.
- Neuropsychology and Rehabilitation Psychology, Radboud University, Montessorilaan 3, 6525 HR, Nijmegen, The Netherlands.
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9
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Rhodes S, Parra MA, Logie RH. Ageing and Feature Binding in Visual Working Memory: The Role of Presentation Time. Q J Exp Psychol (Hove) 2016; 69:654-68. [DOI: 10.1080/17470218.2015.1038571] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
A large body of research has clearly demonstrated that healthy ageing is accompanied by an associative memory deficit. Older adults exhibit disproportionately poor performance on memory tasks requiring the retention of associations between items (e.g., pairs of unrelated words). In contrast to this robust deficit, older adults’ ability to form and temporarily hold bound representations of an object's surface features, such as colour and shape, appears to be relatively well preserved. However, the findings of one set of experiments suggest that older adults may struggle to form temporary bound representations in visual working memory when given more time to study objects. However, these findings were based on between-participant comparisons across experimental paradigms. The present study directly assesses the role of presentation time in the ability of younger and older adults to bind shape and colour in visual working memory using a within-participant design. We report new evidence that giving older adults longer to study memory objects does not differentially affect their immediate memory for feature combinations relative to individual features. This is in line with a growing body of research suggesting that there is no age-related impairment in immediate memory for colour-shape binding.
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Affiliation(s)
- Stephen Rhodes
- Department of Psychology, Centre for Cognitive Ageing and Cognitive Epidemiology, and Human Cognitive Neuroscience, University of Edinburgh, Edinburgh, UK
| | - Mario A. Parra
- Department of Psychology, Centre for Cognitive Ageing and Cognitive Epidemiology, and Human Cognitive Neuroscience, University of Edinburgh, Edinburgh, UK
- Alzheimer Scotland Dementia Research Centre, University of Edinburgh, Edinburgh, UK
- UDP-INECO Foundation Core on Neuroscience (UIFCoN), Diego Portales University, Santiago, Chile
| | - Robert H. Logie
- Department of Psychology, Centre for Cognitive Ageing and Cognitive Epidemiology, and Human Cognitive Neuroscience, University of Edinburgh, Edinburgh, UK
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10
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Bergmann HC, Daselaar SM, Beul SF, Rijpkema M, Fernández G, Kessels RPC. Brain activation during associative short-term memory maintenance is not predictive for subsequent retrieval. Front Hum Neurosci 2015; 9:479. [PMID: 26388758 PMCID: PMC4556991 DOI: 10.3389/fnhum.2015.00479] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2015] [Accepted: 08/17/2015] [Indexed: 12/02/2022] Open
Abstract
Performance on working memory (WM) tasks may partially be supported by long-term memory (LTM) processing. Hence, brain activation recently being implicated in WM may actually have been driven by (incidental) LTM formation. We examined which brain regions actually support successful WM processing, rather than being confounded by LTM processes, during the maintenance and probe phase of a WM task. We administered a four-pair (faces and houses) associative delayed-match-to-sample (WM) task using event-related functional MRI (fMRI) and a subsequent associative recognition LTM task, using the same stimuli. This enabled us to analyze subsequent memory effects for both the WM and the LTM test by contrasting correctly recognized pairs with incorrect pairs for either task. Critically, with respect to the subsequent WM effect, we computed this analysis exclusively for trials that were forgotten in the subsequent LTM recognition task. Hence, brain activity associated with successful WM processing was less likely to be confounded by incidental LTM formation. The subsequent LTM effect, in contrast, was analyzed exclusively for pairs that previously had been correctly recognized in the WM task, disclosing brain regions involved in successful LTM formation after successful WM processing. Results for the subsequent WM effect showed no significantly activated brain areas for WM maintenance, possibly due to an insensitivity of fMRI to mechanisms underlying active WM maintenance. In contrast, a correct decision at WM probe was linked to activation in the “retrieval success network” (anterior and posterior midline brain structures). The subsequent LTM analyses revealed greater activation in left dorsolateral prefrontal cortex and posterior parietal cortex in the early phase of the maintenance stage. No supra-threshold activation was found during the WM probe. Together, we obtained clearer insights in which brain regions support successful WM and LTM without the potential confound of the respective memory system.
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Affiliation(s)
- Heiko C Bergmann
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Netherlands
| | - Sander M Daselaar
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Netherlands
| | - Sarah F Beul
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Netherlands ; Department of Computational Neuroscience, University Medical Center Hamburg-Eppendorf Hamburg, Germany
| | - Mark Rijpkema
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Netherlands ; Department of Radiology and Nuclear Medicine, Radboud University Medical Center Nijmegen, Netherlands
| | - Guillén Fernández
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Netherlands ; Department of Cognitive Neuroscience, Radboud University Medical Center Nijmegen, Netherlands
| | - Roy P C Kessels
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Netherlands ; Department of Medical Psychology, Radboud University Medical Center Nijmegen, Netherlands
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van Geldorp B, Heringa SM, van den Berg E, Olde Rikkert MGM, Biessels GJ, Kessels RPC. Working memory binding and episodic memory formation in aging, mild cognitive impairment, and Alzheimer's dementia. J Clin Exp Neuropsychol 2015; 37:538-48. [PMID: 26011711 DOI: 10.1080/13803395.2015.1037722] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
INTRODUCTION Recent studies indicate that in both normal and pathological aging working memory (WM) performance deteriorates, especially when associations have to be maintained. However, most studies typically do not assess the relationship between WM and episodic memory formation. In the present study, we examined WM and episodic memory formation in normal aging and in patients with early Alzheimer's disease (mild cognitive impairment, MCI; and Alzheimer's dementia, AD). METHOD In the first study, 26 young adults (mean age 29.6 years) were compared to 18 middle-aged adults (mean age 52.2 years) and 25 older adults (mean age 72.8 years). We used an associative delayed-match-to-sample WM task, which requires participants to maintain two pairs of faces and houses presented on a computer screen for short (3 s) or long (6 s) maintenance intervals. After the WM task, an unexpected subsequent associative memory task was administered (two-alternative forced choice). In the second study, 27 patients with AD and 19 patients with MCI were compared to 25 older controls, using the same paradigm as that in Experiment 1. RESULTS Older adults performed worse than both middle-aged and young adults. No effect of delay was observed in the healthy adults, and pairs that were processed during long maintenance intervals were not better remembered in the subsequent memory task. In the MCI and AD patients, longer maintenance intervals hampered the task performance. Also, both patient groups performed significantly worse than controls on the episodic memory task as well as the associative WM task. CONCLUSIONS Aging and AD present with a decline in WM binding, a finding that extends similar results in episodic memory. Longer delays in the WM task did not affect episodic memory formation. We conclude that WM deficits are found when WM capacity is exceeded, which may occur during associative processing.
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Affiliation(s)
- Bonnie van Geldorp
- a Donders Institute for Brain, Cognition and Behaviour, Radboud University , Nijmegen , The Netherlands
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12
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Memory integration in amnesia: prior knowledge supports verbal short-term memory. Neuropsychologia 2015; 70:272-80. [PMID: 25752585 DOI: 10.1016/j.neuropsychologia.2015.02.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 01/22/2015] [Accepted: 02/03/2015] [Indexed: 11/21/2022]
Abstract
Short-term memory (STM) and long-term memory (LTM) have traditionally been considered cognitively distinct. However, it is known that STM can improve when to-be-remembered information appears in contexts that make contact with prior knowledge, suggesting a more interactive relationship between STM and LTM. The current study investigated whether the ability to leverage LTM in support of STM critically depends on the integrity of the hippocampus. Specifically, we investigated whether the hippocampus differentially supports between-domain versus within-domain STM-LTM integration given prior evidence that the representational domain of the elements being integrated in memory is a critical determinant of whether memory performance depends on the hippocampus. In Experiment 1, we investigated hippocampal contributions to within-domain STM-LTM integration by testing whether immediate verbal recall of words improves in MTL amnesic patients when words are presented in familiar verbal contexts (meaningful sentences) compared to unfamiliar verbal contexts (random word lists). Patients demonstrated a robust sentence superiority effect, whereby verbal STM performance improved in familiar compared to unfamiliar verbal contexts, and the magnitude of this effect did not differ from that in controls. In Experiment 2, we investigated hippocampal contributions to between-domain STM-LTM integration by testing whether immediate verbal recall of digits improves in MTL amnesic patients when digits are presented in a familiar visuospatial context (a typical keypad layout) compared to an unfamiliar visuospatial context (a random keypad layout). Immediate verbal recall improved in both patients and controls when digits were presented in the familiar compared to the unfamiliar keypad array, indicating a preserved ability to integrate activated verbal information with stored visuospatial knowledge. Together, these results demonstrate that immediate verbal recall in amnesia can benefit from two distinct types of semantic support, verbal and visuospatial, and that the hippocampus is not critical for leveraging stored semantic knowledge to improve memory performance.
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13
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van Geldorp B, Parra MA, Kessels RPC. Cognitive and neuropsychological underpinnings of relational and conjunctive working memory binding across age. Memory 2014; 23:1112-22. [DOI: 10.1080/09658211.2014.953959] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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14
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Kraguljac NV, White DM, Hadley J, Reid MA, Lahti AC. Hippocampal-parietal dysconnectivity and glutamate abnormalities in unmedicated patients with schizophrenia. Hippocampus 2014; 24:1524-32. [PMID: 25045047 DOI: 10.1002/hipo.22332] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/13/2014] [Indexed: 01/09/2023]
Abstract
Abnormalities in resting state connectivity in schizophrenia (SZ) are now well established, but the biological substrates of these functional alterations remain to be elucidated. We performed a combined functional magnetic resonance imaging and magnetic resonance spectroscopy study in 22 unmedicated patients with SZ and 22 matched healthy controls (HCs) to evaluate resting state functional connectivity of the hippocampus and Glx/Cr (a combined glutamate + glutamine peak normalized to creatine) in the hippocampus and investigate functional and neurometabolic abnormalities and examine the relationship between these. Functional connectivity between the left hippocampus and bilateral precuneus was significantly decreased in unmedicated patients with SZ when compared to HCs [t(4.22), cluster extent (kE) = 751, PFDRcorr = 0.001, Montreal Neurological Institute coordinates: x = -4, y = -56, z = 44]. Glx/Cr in the hippocampus was significantly elevated in SZ (HC: mean = 0.60+/-0.10 SZ: 0.67+/-0.10; F = 5.742; P = 0.02), but was not correlated with functional connectivity deficits (P > 0.05). In this study, we found hippocampal resting state functional connectivity deficits to the precuneus in unmedicated patients with SZ and an increase of Glx/Cr in the hippocampus, but did not observe a direct relationship between these abnormalities. However, our findings do not exclude the possibility of a shared underlying pathology, which warrants further investigation.
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Affiliation(s)
- Nina Vanessa Kraguljac
- Department of Psychiatry and Behavioral Neurobiology, University of Alabama at Birmingham
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van Geldorp B, Bouman Z, Hendriks MP, Kessels RP. Different types of working memory binding in epilepsy patients with unilateral anterior temporal lobectomy. Brain Cogn 2014; 85:231-8. [DOI: 10.1016/j.bandc.2013.12.009] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Revised: 12/18/2013] [Accepted: 12/26/2013] [Indexed: 10/25/2022]
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Race E, LaRocque KF, Keane MM, Verfaellie M. Medial temporal lobe contributions to short-term memory for faces. J Exp Psychol Gen 2013; 142:1309-22. [PMID: 23937185 DOI: 10.1037/a0033612] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The role of the medial temporal lobes (MTL) in short-term memory (STM) remains a matter of debate. Whereas imaging studies commonly show hippocampal activation during short-delay memory tasks, evidence from amnesic patients with MTL lesions is mixed. It has been argued that apparent STM impairments in amnesia may reflect long-term memory (LTM) contributions to performance. We challenge this conclusion by demonstrating that MTL amnesic patients show impaired delayed matching-to-sample (DMS) for faces in a task that meets both a traditional delay-based and a recently proposed distractor-based criterion for classification as an STM task. In Experiment 1, we demonstrate that our face DMS task meets the proposed distractor-based criterion for STM classification, in that extensive processing of delay-period distractor stimuli disrupts performance of healthy individuals. In Experiment 2, MTL amnesic patients with lesions extending into anterior subhippocampal cortex, but not patients with lesions limited to the hippocampus, show impaired performance on this task without distraction at delays as short as 8 s, within temporal range of delay-based STM classification, in the context of intact perceptual matching performance. Experiment 3 provides support for the hypothesis that STM for faces relies on configural processing by showing that the extent to which healthy participants' performance is disrupted by interference depends on the configural demands of the distractor task. Together, these findings are consistent with the notion that the amnesic impairment in STM for faces reflects a deficit in configural processing associated with subhippocampal cortices and provide novel evidence that the MTL supports cognition beyond the LTM domain.
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Affiliation(s)
- Elizabeth Race
- Memory Disorders Research Center, VA Boston Healthcare System
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17
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Odegard TN, Cooper CM, Farris EA, Arduengo J, Bartlett J, Haley R. Memory impairment exhibited by veterans with Gulf War Illness. Neurocase 2013; 19:316-27. [PMID: 22519425 DOI: 10.1080/13554794.2012.667126] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
Roughly 26-32% of US veterans, who served in the first Gulf War, report suffering from chronic health problems ( Golomb, 2008 , Proceedings of the National Academies of Science, 105, 4295). The present study investigated the memory deficits reported by these ill Gulf War veterans (GWV) using a face-name associative memory paradigm administered during functional magnetic resonance imaging (fMRI). The fMRI data confirmed memory performance on the memory task to be related to the amount of activation in the left hippocampus observed during the study. In addition, ill-GWV demonstrated decreased memory performance relative to unaffected GWV on this memory test, providing evidence of memory deficits using an objective measure of memory.
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Affiliation(s)
- Timothy N Odegard
- Department of Psychology, University Texas Arlington, Arlington, TX 76019-0528, USA.
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Newmark RE, Schon K, Ross RS, Stern CE. Contributions of the hippocampal subfields and entorhinal cortex to disambiguation during working memory. Hippocampus 2013; 23:467-75. [PMID: 23504938 DOI: 10.1002/hipo.22106] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/16/2013] [Indexed: 11/08/2022]
Abstract
The hippocampus and medial temporal lobes (MTL) support the successful formation of new memories without succumbing to interference from related, older memories. Computational models and animal findings have implicated the dentate gyrus (DG), CA3, CA1, and entorhinal cortex (EC) in the disambiguation and encoding of well-established, episodic events that share common elements. However, it is unknown if these hippocampal subfields and MTL (entorhinal, perirhinal, parahippocampal) cortices also contribute during working memory when overlapping stimuli that share related features are rapidly encoded and subsequently maintained over a brief temporal delay. We hypothesized that activity in CA3/DG hippocampal subfields would be greater for the rapid encoding of stimuli with overlapping features than for the rapid encoding of stimuli with distinct features. In addition, we predicted that CA1 and EC, regions that are associated with creating long-term episodic representations, would show greater sustained activity across both encoding and delay periods for representations of stimuli with overlapping features than for those with distinct features. We used high-resolution fMRI during a delayed matching-to-sample (DMS) task using face pairs that either shared (overlapping condition, OL) or did not share (non-overlapping condition, NOL) common elements. We contrasted the OL condition with the NOL condition separately at sample (encoding) and during a brief delay (maintenance). At sample, we observed activity localized to CA3/DG, the subiculum, and CA1. At delay, we observed activity localized to the subiculum and CA1 and activity within the entorhinal, perirhinal, and parahippocampal cortices. Our findings are consistent with our hypotheses and suggest that CA3/DG, CA1 and the subiculum support the disambiguation and encoding of overlapping representations while CA1, subiculum and entorhinal cortex maintain these overlapping representations during working memory.
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Affiliation(s)
- Randall E Newmark
- Department of Psychology, Center for Memory and Brain, Boston University, Boston, Massachusetts, USA
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Hippocampal structure and human cognition: key role of spatial processing and evidence supporting the efficiency hypothesis in females. INTELLIGENCE 2013; 41:129-140. [PMID: 25632167 DOI: 10.1016/j.intell.2013.01.002] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Here we apply a method for automated segmentation of the hippocampus in 3D high-resolution structural brain MRI scans. One hundred and four healthy young adults completed twenty one tasks measuring abstract, verbal, and spatial intelligence, along with working memory, executive control, attention, and processing speed. After permutation tests corrected for multiple comparisons across vertices (p < .05) significant relationships were found for spatial intelligence, spatial working memory, and spatial executive control. Interactions with sex revealed significant relationships with the general factor of intelligence (g), along with abstract and spatial intelligence. These correlations were mainly positive for males but negative for females, which might support the efficiency hypothesis in women. Verbal intelligence, attention, and processing speed were not related to hippocampal structural differences.
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Schon K, Ross RS, Hasselmo ME, Stern CE. Complementary roles of medial temporal lobes and mid-dorsolateral prefrontal cortex for working memory for novel and familiar trial-unique visual stimuli. Eur J Neurosci 2012; 37:668-78. [DOI: 10.1111/ejn.12062] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2012] [Revised: 09/28/2012] [Accepted: 10/22/2012] [Indexed: 11/29/2022]
Affiliation(s)
| | | | - Michael E. Hasselmo
- Department of Psychology and Center for Memory and Brain; Center of Excellence for Learning in Education, Science, and Technology - CELEST; Boston University; Boston; MA; 02215; USA
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Abstract
Memory for contextual information and target-context integration are crucial for successful episodic memory formation and are impaired in patients with Korsakoff's syndrome. In this paper we review the evidence for the notion that a context memory deficit makes an important contribution to the amnesia in these patients. First, we focus on anterograde memory for contextual (spatial and temporal) information. Next, the use of contextual cues in memory retrieval is examined and their role in retrograde amnesia and confabulation. Evidence on the role of contextual cues and associations in working memory is discussed in relation to the underlying neurocognitive mechanisms and their dissociation from long-term encoding. Finally, we focus on implicit learning of contextual information in Korsakoff patients. It can be concluded that Korsakoff patients are impaired in the explicit processing of contextual information and in target-context binding, both in long-term (retrograde and anterograde) memory and in working memory. These results extend the context memory deficit hypothesis. In contrast, implicit contextual learning is relatively preserved in these patients. These findings are discussed in relation to evidence of dysfunction of the extended diencephalic-hippocampal memory circuit in Korsakoff's syndrome.
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Affiliation(s)
- Roy P. C. Kessels
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, PO Box 9104, 6500 HE Nijmegen, The Netherlands
- Vincent van Gogh Institute for Psychiatry, Korsakoff Clinic, Venray, The Netherlands
- Department of Medical Psychology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Michael D. Kopelman
- King’s College London, Institute of Psychiatry, Division of Psychological Medicine, Neuropsychiatry and Memory Disorders Clinic, Academic Unit of Neuropsychiatry, 3rd Floor Adamson Centre, South Wing, St. Thomas’s Hospital, Lambeth Palace Road, London, SE1 7EH UK
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22
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Short-term memory binding is impaired in AD but not in non-AD dementias. Neuropsychologia 2012; 50:833-40. [DOI: 10.1016/j.neuropsychologia.2012.01.018] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2011] [Revised: 01/11/2012] [Accepted: 01/13/2012] [Indexed: 10/14/2022]
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Bergmann HC, Rijpkema M, Fernández G, Kessels RPC. Distinct neural correlates of associative working memory and long-term memory encoding in the medial temporal lobe. Neuroimage 2012; 63:989-97. [PMID: 22484305 DOI: 10.1016/j.neuroimage.2012.03.047] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2011] [Revised: 02/13/2012] [Accepted: 03/14/2012] [Indexed: 10/28/2022] Open
Abstract
Increasing evidence suggests a role for the hippocampus not only in long-term memory (LTM) but also in relational working memory (WM) processes, challenging the view of the hippocampus as being solely involved in episodic LTM. However, hippocampal involvement reported in some neuroimaging studies using "classical" WM tasks may at least partly reflect incidental LTM encoding. To disentangle WM processing and LTM formation we administered a delayed-match-to-sample associative WM task in an event-related fMRI study design. Each trial of the WM task consisted of four pairs of faces and houses, which had to be maintained during a delay of 10 s. This was followed by a probe phase consisting of three consecutively presented pairs; for each pair participants were to indicate whether it matched one of the pairs of the encoding phase. After scanning, an unexpected recognition-memory (LTM) task was administered. Brain activity during encoding was analyzed based on WM and LTM performance. Hence, encoding-related activity predicting WM success in the absence of successful LTM formation could be isolated. Furthermore, regions critical for successful LTM formation for pairs previously correctly processed in WM were analyzed. Results showed that the left parahippocampal gyrus including the fusiform gyrus predicted subsequent accuracy on WM decisions. The right anterior hippocampus and left inferior frontal gyrus, in contrast, predicted successful LTM for pairs that were previously correctly classified in the WM task. Our results suggest that brain regions associated with higher-level visuo-perceptual processing are involved in successful associative WM encoding, whereas the anterior hippocampus and left inferior frontal gyrus are involved in successful LTM formation during incidental encoding.
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Affiliation(s)
- Heiko C Bergmann
- Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, P.O. Box 9104, 6500HB Nijmegen, The Netherlands.
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Jeneson A, Squire LR. Working memory, long-term memory, and medial temporal lobe function. Learn Mem 2012; 19:15-25. [PMID: 22180053 PMCID: PMC3246590 DOI: 10.1101/lm.024018.111] [Citation(s) in RCA: 226] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Accepted: 10/28/2011] [Indexed: 11/24/2022]
Abstract
Early studies of memory-impaired patients with medial temporal lobe (MTL) damage led to the view that the hippocampus and related MTL structures are involved in the formation of long-term memory and that immediate memory and working memory are independent of these structures. This traditional idea has recently been revisited. Impaired performance in patients with MTL lesions on tasks with short retention intervals, or no retention interval, and neuroimaging findings with similar tasks have been interpreted to mean that the MTL is sometimes needed for working memory and possibly even for visual perception itself. We present a reappraisal of this interpretation. Our main conclusion is that, if the material to be learned exceeds working memory capacity, if the material is difficult to rehearse, or if attention is diverted, performance depends on long-term memory even when the retention interval is brief. This fundamental notion is better captured by the terms subspan memory and supraspan memory than by the terms short-term memory and long-term memory. We propose methods for determining when performance on short-delay tasks must depend on long-term (supraspan) memory and suggest that MTL lesions impair performance only when immediate memory and working memory are insufficient to support performance. In neuroimaging studies, MTL activity during encoding is influenced by the memory load and correlates positively with long-term retention of the material that was presented. The most parsimonious and consistent interpretation of all the data is that subspan memoranda are supported by immediate memory and working memory and are independent of the MTL.
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Affiliation(s)
- Annette Jeneson
- Department of Psychology, University of California, San Diego, California 92093
| | - Larry R. Squire
- Department of Psychology, University of California, San Diego, California 92093
- Department of Psychiatry, University of California, San Diego, California 92093
- Department of Neurosciences, University of California, San Diego, California 92093
- Veterans Affairs Medical Center, San Diego, California 92161
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van Geldorp B, Bergmann HC, Robertson J, Wester AJ, Kessels RPC. The interaction of working memory performance and episodic memory formation in patients with Korsakoff's amnesia. Brain Res 2011; 1433:98-103. [PMID: 22177773 DOI: 10.1016/j.brainres.2011.11.036] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 11/15/2011] [Indexed: 11/25/2022]
Abstract
Both neuroimaging work and studies investigating amnesic patients have shown involvement of the medial temporal lobe during working memory tasks, especially when multiple items or features have to be associated. However, so far no study has examined the relationship between working memory and subsequent episodic memory in patients using similar tasks. In this study, we compared patients with amnesia due to Korsakoff's syndrome (n=19) with healthy controls (n=18) on an associative working memory task followed by an unexpected subsequent episodic memory task. The computerized working memory task required participants to maintain two pairs of faces and houses for either short (3s) or long (6s) delays. Approximately 5 minutes after completion of the working memory task, an unexpected subsequent recognition task with a two-alternative forced choice paradigm was administered. By directly comparing working memory and subsequent episodic memory, we were able to examine long-term encoding processes that may take place after longer delays. As expected, patients performed at chance level on the episodic memory task. Interestingly, patients also showed significantly impaired working memory performance (p<.01), even at short delays. Longer delays did not result in better subsequent memory, indicating that they do not facilitate long-term encoding processes. Our results are discussed in relation to Baddeley's working memory model as the episodic buffer is assumed to be a short-term store for maintaining bound representations. In light of these results, the long-standing view that working memory and long-term memory are strictly dissociated may need to be revisited.
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Affiliation(s)
- Bonnie van Geldorp
- Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Nijmegen, The Netherlands.
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Medial temporal lobe damage causes deficits in episodic memory and episodic future thinking not attributable to deficits in narrative construction. J Neurosci 2011; 31:10262-9. [PMID: 21753003 DOI: 10.1523/jneurosci.1145-11.2011] [Citation(s) in RCA: 225] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The medial temporal lobe (MTL) makes critical contributions to episodic memory, but its contributions to episodic future thinking remain a matter of debate. By one view, imagining future events relies on MTL mechanisms that also support memory for past events. Alternatively, it has recently been suggested that future thinking is independent of MTL-mediated processes and can be supported by regions outside the MTL. The current study investigated the nature and necessity of MTL involvement in imagining the future and tested the novel hypothesis that the MTL contributes to future thinking by supporting online binding processes related to narrative construction. Human amnesic patients with well characterized MTL damage and healthy controls constructed narratives about (1) future events, (2) past events, and (3) visually presented pictures. While all three tasks place similar demands on narrative construction, only the past and future conditions require memory/future thinking to mentally generate relevant narrative information. Patients produced impoverished descriptions of both past and future events but were unimpaired at producing detailed picture narratives. In addition, future-thinking performance positively correlated with episodic memory performance but did not correlate with picture narrative performance. Finally, future-thinking impairments were present when MTL lesions were restricted to the hippocampus and did not depend on the presence of neural damage outside the MTL. These results indicate that the ability to generate and maintain a detailed narrative is preserved in amnesia and suggest that a common MTL mechanism supports both episodic memory and episodic future thinking.
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Forebrain NR2B overexpression facilitating the prefrontal cortex long-term potentiation and enhancing working memory function in mice. PLoS One 2011; 6:e20312. [PMID: 21655294 PMCID: PMC3105019 DOI: 10.1371/journal.pone.0020312] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Accepted: 04/26/2011] [Indexed: 11/19/2022] Open
Abstract
Prefrontal cortex plays an important role in working memory, attention regulation and behavioral inhibition. Its functions are associated with NMDA receptors. However, there is little information regarding the roles of NMDA receptor NR2B subunit in prefrontal cortical synaptic plasticity and prefrontal cortex-related working memory. Whether the up-regulation of NR2B subunit influences prefrontal cortical synaptic plasticity and working memory is not yet clear. In the present study, we measured prefrontal cortical synaptic plasticity and working memory function in NR2B overexpressing transgenic mice. In vitro electrophysiological data showed that overexpression of NR2B specifically in the forebrain region resulted in enhancement of prefrontal cortical long-term potentiation (LTP) but did not alter long-term depression (LTD). The enhanced LTP was completely abolished by a NR2B subunit selective antagonist, Ro25-6981, indicating that overexpression of NR2B subunit is responsible for enhanced LTP. In addition, NR2B transgenic mice exhibited better performance in a set of working memory paradigms including delay no-match-to-place T-maze, working memory version of water maze and odor span task. Our study provides evidence that NR2B subunit of NMDA receptor in prefrontal cortex is critical for prefrontal cortex LTP and prefrontal cortex-related working memory.
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Jeneson A, Mauldin KN, Hopkins RO, Squire LR. The role of the hippocampus in retaining relational information across short delays: the importance of memory load. Learn Mem 2011; 18:301-5. [PMID: 21502337 DOI: 10.1101/lm.2010711] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Patients with hippocampal damage are sometimes impaired at remembering information across delays as short as a few seconds. How are these impairments to be understood? One possibility is that retention of some kinds of information is critically dependent on the hippocampus, regardless of the retention interval and regardless of whether the task depends on working memory or long-term memory. Alternatively, retention may be dependent on the hippocampus only when the task involves a memory load large enough to exceed working memory capacity. To explore these possibilities, we assessed the performance of patients with hippocampal lesions on two tasks requiring retention of the same object-in-scene information across a brief delay. The tasks placed different demands on memory. In one task, which used a continuous recognition format, participants needed to try to hold up to nine scenes in mind, even when no scene intervened between the study scene and the corresponding test scene. Patients were impaired in this condition. In a second task, using a conventional study-test format, participants needed to hold in mind only one scene at a time for either 3 or 14 sec. With this procedure, patients performed as well as controls after a 3-sec delay but were impaired after a 14-sec delay. We suggest that retention of object-in-scene information is dependent on the hippocampus only when working memory is insufficient to support performance (because memory load is high or the retention interval is long). In these circumstances performance depends, at least in part, on long-term memory.
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Affiliation(s)
- Annette Jeneson
- Department of Psychology, University of California, San Diego, California 92093, USA
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Liu X, Qin S, Rijpkema M, Luo J, Fernández G. Intermediate levels of hippocampal activity appear optimal for associative memory formation. PLoS One 2010; 5. [PMID: 20957209 PMCID: PMC2948522 DOI: 10.1371/journal.pone.0013147] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2010] [Accepted: 09/07/2010] [Indexed: 11/18/2022] Open
Abstract
Background It is well established that hippocampal activity is positively related to effective associative memory formation. However, in biological systems often optimal levels of activity are contrasted by both sub- and supra-optimal levels. Sub-optimal levels of hippocampal activity are commonly attributed to unsuccessful memory formation, whereas the supra-optimal levels of hippocampal activity related to unsuccessful memory formation have been rarely studied. It is still unclear under what circumstances such supra-optimal levels of hippocampal activity occur. To clarify this issue, we aimed at creating a condition, in which supra-optimal hippocampal activity is associated with encoding failure. We assumed that such supra-optimal activity occurs when task-relevant information is embedded in task-irrelevant, distracting information, which can be considered as noise. Methodology/Principal Findings In the present fMRI study, we probed neural correlates of associative memory formation in a full-factorial design with associative memory (subsequently remembered versus forgotten) and noise (induced by high versus low distraction) as factors. Results showed that encoding failure was associated with supra-optimal activity in the high-distraction condition and with sub-optimal activity in the low distraction condition. Thus, we revealed evidence for a bell-shape function relating hippocampal activity with associative encoding success. Conclusions/Significance Our findings indicate that intermediate levels of hippocampal activity are optimal while both too low and too high levels appear detrimental for associative memory formation. Supra-optimal levels of hippocampal activity seem to occur when task-irrelevant information is added to task-relevant signal. If such task-irrelevant noise is reduced adequately, hippocampal activity is lower and thus optimal for associative memory formation.
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Affiliation(s)
- Xiao Liu
- Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
- Institute of Psychology, Chinese Academy of Sciences (CAS), Beijing, China
- Graduate School, Chinese Academy of Sciences (CAS), Beijing, China
| | - Shaozheng Qin
- Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
- Department of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Mark Rijpkema
- Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Jing Luo
- Institute of Psychology, Chinese Academy of Sciences (CAS), Beijing, China
- * E-mail: (GF); (JL)
| | - Guillén Fernández
- Centre for Cognitive Neuroimaging, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
- Department for Cognitive Neuroscience, Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- * E-mail: (GF); (JL)
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Kessels RPC, Meulenbroek O, Fernández G, Olde Rikkert MGM. Spatial Working Memory in Aging and Mild Cognitive Impairment: Effects of Task Load and Contextual Cueing. AGING NEUROPSYCHOLOGY AND COGNITION 2010; 17:556-74. [DOI: 10.1080/13825585.2010.481354] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Piekema C, Rijpkema M, Fernández G, Kessels RPC. Dissociating the neural correlates of intra-item and inter-item working-memory binding. PLoS One 2010; 5:e10214. [PMID: 20419095 PMCID: PMC2856674 DOI: 10.1371/journal.pone.0010214] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2010] [Accepted: 03/26/2010] [Indexed: 11/22/2022] Open
Abstract
Background Integration of information streams into a unitary representation is an important task of our cognitive system. Within working memory, the medial temporal lobe (MTL) has been conceptually linked to the maintenance of bound representations. In a previous fMRI study, we have shown that the MTL is indeed more active during working-memory maintenance of spatial associations as compared to non-spatial associations or single items. There are two explanations for this result, the mere presence of the spatial component activates the MTL, or the MTL is recruited to bind associations between neurally non-overlapping representations. Methodology/Principal Findings The current fMRI study investigates this issue further by directly comparing intrinsic intra-item binding (object/colour), extrinsic intra-item binding (object/location), and inter-item binding (object/object). The three binding conditions resulted in differential activation of brain regions. Specifically, we show that the MTL is important for establishing extrinsic intra-item associations and inter-item associations, in line with the notion that binding of information processed in different brain regions depends on the MTL. Conclusions/Significance Our findings indicate that different forms of working-memory binding rely on specific neural structures. In addition, these results extend previous reports indicating that the MTL is implicated in working-memory maintenance, challenging the classic distinction between short-term and long-term memory systems.
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Affiliation(s)
- Carinne Piekema
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
- Department of Experimental Psychology, Oxford University, Oxford, United Kingdom
| | - Mark Rijpkema
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
| | - Guillén Fernández
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
- Department of Neurology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Roy P. C. Kessels
- Donders Institute for Brain, Cognition and Behaviour, Radboud University Nijmegen, Nijmegen, The Netherlands
- Departments of Medical Psychology and Geriatric Medicine, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
- * E-mail:
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Crespo-Garcia M, Cantero J, Pomyalov A, Boccaletti S, Atienza M. Functional neural networks underlying semantic encoding of associative memories. Neuroimage 2010; 50:1258-70. [DOI: 10.1016/j.neuroimage.2010.01.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2009] [Revised: 12/21/2009] [Accepted: 01/06/2010] [Indexed: 10/20/2022] Open
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Luck D, Danion JM, Marrer C, Pham BT, Gounot D, Foucher J. The right parahippocampal gyrus contributes to the formation and maintenance of bound information in working memory. Brain Cogn 2010; 72:255-63. [DOI: 10.1016/j.bandc.2009.09.009] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Revised: 09/22/2009] [Accepted: 09/24/2009] [Indexed: 10/20/2022]
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Meulenbroek O, Kessels RP, de Rover M, Petersson KM, Rikkert MGO, Rijpkema M, Fernández G. Age-effects on associative object–location memory. Brain Res 2010; 1315:100-10. [DOI: 10.1016/j.brainres.2009.12.011] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Revised: 12/01/2009] [Accepted: 12/05/2009] [Indexed: 10/20/2022]
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