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Effects of Scrophularia buergeriana Extract (Brainon ®) on Aging-Induced Memory Impairment in SAMP8 Mice. Curr Issues Mol Biol 2023; 45:1287-1305. [PMID: 36826029 PMCID: PMC9955813 DOI: 10.3390/cimb45020084] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2023] [Revised: 01/30/2023] [Accepted: 02/01/2023] [Indexed: 02/09/2023] Open
Abstract
Alzheimer's disease (AD) is a worldwide problem. Currently, there are no effective drugs for AD treatment. Scrophularia buergeriana Miquel (SB) is a traditional herbal medicine used in Korea to treat various diseases. Our previous studies have shown that ethanol extract of SB roots (SBE, Brainon®) exhibits potent anti-amnesic effects in Aβ1-42- or scopolamine-treated memory impairment mice model and neuroprotective effects in a glutamate-induced SH-SY5Y cell model. In this study, we evaluated the therapeutic effects of Brainon® and its mechanism of action in senescence-accelerated mouse prone 8 (SAMP8) mice. Brainon® (30 or 100 mg/kg/day) was orally treated to six-month-old SAMP8 mice for 12 weeks. Results revealed that Brainon® administration effectually ameliorated cognitive deficits in Y-maze and passive avoidance tests. Following the completion of behavioral testing, western blotting was performed using the cerebral cortex. Results revealed that Brainon® suppressed Aβ1-42 accumulation, Tau hyperphosphorylation, oxidative stress, and inflammation and alleviated apoptosis in SAMP8 mice. Brainon® also promoted synaptic function by downregulating the expression of AChE and upregulating the expression of p-CREB/CREB and BDNF. Furthermore, Brainon® restored SAMP8-reduced expression of ChAT and -dephosphorylated of ERK and also decreased AChE expression in the hippocampus. Furthermore, Brainon® alleviated AD progression by promoting mitophagy/autophagy to maintain normal cellular function as a novel finding of this study. Our data suggest that Brainon® can remarkably improve cognitive deficiency with the potential to be utilized in functional food for improving brain health.
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Rodríguez-Flores TC, Palomo-Briones GA, Robles F, Ramos F. Proposal for a computational model of incentive memory. COGN SYST RES 2022. [DOI: 10.1016/j.cogsys.2022.11.002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Wirtshafter HS, Disterhoft JF. In Vivo Multi-Day Calcium Imaging of CA1 Hippocampus in Freely Moving Rats Reveals a High Preponderance of Place Cells with Consistent Place Fields. J Neurosci 2022; 42:4538-4554. [PMID: 35501152 PMCID: PMC9172072 DOI: 10.1523/jneurosci.1750-21.2022] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 04/15/2022] [Accepted: 04/19/2022] [Indexed: 11/21/2022] Open
Abstract
Calcium imaging using GCaMP indicators and miniature microscopes has been used to image cellular populations during long timescales and in different task phases, as well as to determine neuronal circuit topology and organization. Because the hippocampus (HPC) is essential for tasks of memory, spatial navigation, and learning, calcium imaging of large populations of HPC neurons can provide new insight on cell changes over time during these tasks. All reported HPC in vivo calcium imaging experiments have been done in mouse. However, rats have many behavioral and physiological experimental advantages over mice. In this paper, we present the first (to our knowledge) in vivo calcium imaging from CA1 HPC in freely moving male rats. Using the UCLA Miniscope, we demonstrate that, in rat, hundreds of cells can be visualized and held across weeks. We show that calcium events in these cells are highly correlated with periods of movement, with few calcium events occurring during periods without movement. We additionally show that an extremely large percent of cells recorded during a navigational task are place cells (77.3 ± 5.0%, surpassing the percent seen during mouse calcium imaging), and that these cells enable accurate decoding of animal position and can be held over days with consistent place fields in a consistent spatial map. A detailed protocol is included, and implications of these advancements on in vivo imaging and place field literature are discussed.SIGNIFICANCE STATEMENT In vivo calcium imaging in freely moving animals allows the visualization of cellular activity across days. In this paper, we present the first in vivo Ca2+ recording from CA1 hippocampus (HPC) in freely moving rats. We demonstrate that hundreds of cells can be visualized and held across weeks, and that calcium activity corresponds to periods of movement. We show that a high percentage (77.3 ± 5.0%) of imaged cells are place cells, and that these place cells enable accurate decoding and can be held stably over days with little change in field location. Because the HPC is essential for many tasks involving memory, navigation, and learning, imaging of large populations of HPC neurons can shed new insight on cellular activity changes and organization.
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Affiliation(s)
- Hannah S Wirtshafter
- Department of Neuroscience, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
| | - John F Disterhoft
- Department of Neuroscience, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611
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De Meo E, Portaccio E, Prestipino E, Nacmias B, Bagnoli S, Razzolini L, Pastò L, Niccolai C, Goretti B, Bellinvia A, Fonderico M, Giorgio A, Stromillo ML, Filippi M, Sorbi S, De Stefano N, Amato MP. Effect of BDNF Val66Met polymorphism on hippocampal subfields in multiple sclerosis patients. Mol Psychiatry 2022; 27:1010-1019. [PMID: 34650209 DOI: 10.1038/s41380-021-01345-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 10/01/2021] [Accepted: 10/04/2021] [Indexed: 01/20/2023]
Abstract
Brain-derived neurotrophic factor (BDNF) Val66Met polymorphism was shown to strongly affect BDNF function, but its role in modulating gray matter damage in multiple sclerosis (MS) patients is still not clear. Given BDNF relevance on the hippocampus, we aimed to explore BDNF Val66Met polymorphism effect on hippocampal subfield volumes and its role in cognitive functioning in MS patients. Using a 3T scanner, we obtained dual-echo and 3DT1-weighted sequences from 50 MS patients and 15 healthy controls (HC) consecutively enrolled. MS patients also underwent genotype analysis of BDNF, neurological and neuropsychological evaluation. Hippocampal subfields were segmented by using Freesurfer. The BDNF Val66Met polymorphism was found in 22 MS patients (44%). Compared to HC, MS patients had lower volume in: bilateral hippocampus-amygdala transition area (HATA); cornus ammonis (CA)1, granule cell layer of dentate gyrus (GCL-DG), CA4 and CA3 of the left hippocampal head; molecular layer (ML) of the left hippocampal body; presubiculum of right hippocampal body and right fimbria. Compared to BDNF Val66Val, Val66Met MS patients had higher volume in bilateral hippocampal tail; CA1, ML, CA3, CA4, and GCL-DG of left hippocampal head; CA1, ML, and CA3 of the left hippocampal body; left HATA and presubiculum of the right hippocampal head. In MS patients, higher lesion burden was associated with lower volume of presubiculum of right hippocampal body; lower volume of left hippocampal tail was associated with worse visuospatial memory performance; lower volume of left hippocampal head with worse performance in semantic fluency. Our findings suggest the BNDF Val66Met polymorphism may have a protective role in MS patients against both hippocampal atrophy and cognitive impairment. BDNF genotype might be a potential biomarker for predicting cognitive prognosis, and an interesting target to study for neuroprotective strategies.
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Affiliation(s)
- Ermelinda De Meo
- Neuroimaging Research Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy. .,Vita-Salute San Raffaele University, Milan, Italy.
| | - Emilio Portaccio
- Department NEUROFARBA, Section Neurosciences, University of Florence, Florence, Italy.,IRCCS Fondazione Don Carlo Gnocchi, Florence, Italy
| | - Elio Prestipino
- Department NEUROFARBA, Section Neurosciences, University of Florence, Florence, Italy
| | - Benedetta Nacmias
- Department NEUROFARBA, Section Neurosciences, University of Florence, Florence, Italy.,IRCCS Fondazione Don Carlo Gnocchi, Florence, Italy
| | - Silvia Bagnoli
- Department NEUROFARBA, Section Neurosciences, University of Florence, Florence, Italy
| | | | - Luisa Pastò
- Azienda Ospedaliero-Universitaria Careggi, Florence, Italy
| | | | - Benedetta Goretti
- Department NEUROFARBA, Section Neurosciences, University of Florence, Florence, Italy
| | | | | | - Antonio Giorgio
- Department of Medicine, Surgery and Neuroscience, University of Siena, Siena, Italy
| | | | - Massimo Filippi
- Neuroimaging Research Unit, Division of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, Italy.,Vita-Salute San Raffaele University, Milan, Italy.,Neurology Unit,, IRCCS San Raffaele Scientific Institute, Milan, Italy.,Neurophysiology Unit, IRCCS San Raffaele Scientific Institute, Milan, Italy
| | - Sandro Sorbi
- Department NEUROFARBA, Section Neurosciences, University of Florence, Florence, Italy.,IRCCS Fondazione Don Carlo Gnocchi, Florence, Italy
| | - Nicola De Stefano
- Department of Medicine, Surgery and Neuroscience, University of Siena, Siena, Italy
| | - Maria Pia Amato
- Department NEUROFARBA, Section Neurosciences, University of Florence, Florence, Italy.,IRCCS Fondazione Don Carlo Gnocchi, Florence, Italy
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Zhou G, Olofsson JK, Koubeissi MZ, Menelaou G, Rosenow J, Schuele SU, Xu P, Voss JL, Lane G, Zelano C. Human hippocampal connectivity is stronger in olfaction than other sensory systems. Prog Neurobiol 2021; 201:102027. [PMID: 33640412 DOI: 10.1016/j.pneurobio.2021.102027] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2020] [Revised: 01/20/2021] [Accepted: 02/21/2021] [Indexed: 12/17/2022]
Abstract
During mammalian evolution, primate neocortex expanded, shifting hippocampal functional networks away from primary sensory cortices, towards association cortices. Reflecting this rerouting, human resting hippocampal functional networks preferentially include higher association cortices, while those in rodents retained primary sensory cortices. Research on human visual, auditory and somatosensory systems shows evidence of this rerouting. Olfaction, however, is unique among sensory systems in its relative structural conservation throughout mammalian evolution, and it is unknown whether human primary olfactory cortex was subject to the same rerouting. We combined functional neuroimaging and intracranial electrophysiology to directly compare hippocampal functional networks across human sensory systems. We show that human primary olfactory cortex-including the anterior olfactory nucleus, olfactory tubercle and piriform cortex-has stronger functional connectivity with hippocampal networks at rest, compared to other sensory systems. This suggests that unlike other sensory systems, olfactory-hippocampal connectivity may have been retained in mammalian evolution. We further show that olfactory-hippocampal connectivity oscillates with nasal breathing. Our findings suggest olfaction might provide insight into how memory and cognition depend on hippocampal interactions.
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Affiliation(s)
- Guangyu Zhou
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
| | - Jonas K Olofsson
- Department of Psychology, Stockholm University, Stockholm, Sweden; Emotional Brain Institute, Nathan S. Kline Institute, Orangeburg, NY, USA; Department of Child and Adolescent Psychiatry, New York University School of Medicine, New York, NY, USA
| | | | | | - Joshua Rosenow
- Department of Neurosurgery, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Stephan U Schuele
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Pengfei Xu
- Beijing Key Laboratory of Applied Experimental Psychology, Faculty of Psychology, Beijing Normal University, Beijing, China; Center for Neuroimaging, Shenzhen Institute of Neuroscience, Shenzhen, China; Guangdong-Hong Kong-Macao Greater Bay Area Research Institute for Neuroscience and Neurotechnologies, Kwun Tong, Hong Kong, China
| | - Joel L Voss
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA; Department of Medical Social Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, USA; Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Gregory Lane
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA
| | - Christina Zelano
- Department of Neurology, Northwestern University Feinberg School of Medicine, Chicago, IL, USA.
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Berteau S, Bullock D. Simulations reveal how M-currents and memory-based inputs from CA3 enable single neuron mismatch detection for EC3 inputs to the CA1 subfield of hippocampus. J Neurophysiol 2020; 124:544-556. [PMID: 32609564 DOI: 10.1152/jn.00238.2019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Significant evidence has accumulated to support the hypothesis that hippocampal region CA1 operates as an associative mismatch detector (e.g., Hasselmo ME, Schnell E, Barkai E. J Neurosci 15: 5249-5262, 1995; Duncan K, Curtis C, Davachi L. J Neurosci 29: 131-139, 2009; Kumaran D, Maguire EA. J Neurosci 27: 8517-8524, 2007; Lisman JE, Grace AA. Neuron 46: 703-713, 2005; Lisman JE, Otmakhova NA. Hippocampus 11: 551-568 2001; Lörincz A, Buzsáki G. Ann N Y Acad Sci 911: 83-111, 2000; Meeter M, Murre JMJ, Talamini LM. Hippocampus 14: 722-741, 2004; Schiffer AM, Ahlheim C, Wurm MF, Schubotz RI. PLoS One 7: e36445, 2012; Vinogradova OS. Hippocampus 11: 578-598 2001). CA1 compares predictive synaptic signals from CA3 with synaptic signals from EC3, which reflect actual sensory inputs. The new CA1 pyramidal model presented here shows that the distal-proximal segregation of synaptic inputs from EC3 versus CA3, along with other biophysical features, enable such pyramids to serve as comparators that switch output encoding from a brief burst, for a match, to prolonged tonic spiking, for a mismatch. By including often-overlooked features of CA1 pyramidal neurons, this new model allows simulation of pharmacological effects that can eliminate either the match (phasic mode) response or the mismatch (tonic mode) response. These simulations reveal that dysfunctions can arise from either too much or too little ACh stimulation of the muscarinic receptors that control KCNQ channels. Additionally, a dysfunction caused by administration of an N-methyl-d-aspartate antagonist could be rescued by simultaneous administration of a KCNQ channel agonist, such as retigabine.NEW & NOTEWORTHY Hippocampal region CA1 operates as an associative mismatch detector, comparing predictive signals from CA3 with signals from EC3 reflecting sensory inputs. This new CA1 pyramidal model shows that biophysical features enable these comparators to switch output between brief bursts for matches and tonic spiking for mismatches. This suggests that cognitive learning models (e.g., predictive coding) may require much less match/mismatch circuitry than commonly assumed. Additional simulations illuminate deficits seen in psychiatric disorders and drug-induced states.
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Affiliation(s)
- Stefan Berteau
- Cognitive & Neural Systems Program, Boston University, Boston, Massachusetts
| | - Daniel Bullock
- Cognitive & Neural Systems Program, Boston University, Boston, Massachusetts
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7
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Katona L, Hartwich K, Tomioka R, Somogyi J, Roberts JDB, Wagner K, Joshi A, Klausberger T, Rockland KS, Somogyi P. Synaptic organisation and behaviour-dependent activity of mGluR8a-innervated GABAergic trilaminar cells projecting from the hippocampus to the subiculum. Brain Struct Funct 2020; 225:705-734. [PMID: 32016558 PMCID: PMC7046583 DOI: 10.1007/s00429-020-02029-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2019] [Accepted: 01/16/2020] [Indexed: 02/07/2023]
Abstract
In the hippocampal CA1 area, the GABAergic trilaminar cells have their axon distributed locally in three layers and also innervate the subiculum. Trilaminar cells have a high level of somato-dendritic muscarinic M2 acetylcholine receptor, lack somatostatin expression and their presynaptic inputs are enriched in mGluR8a. But the origin of their inputs and their behaviour-dependent activity remain to be characterised. Here we demonstrate that (1) GABAergic neurons with the molecular features of trilaminar cells are present in CA1 and CA3 in both rats and mice. (2) Trilaminar cells receive mGluR8a-enriched GABAergic inputs, e.g. from the medial septum, which are probably susceptible to hetero-synaptic modulation of neurotransmitter release by group III mGluRs. (3) An electron microscopic analysis identifies trilaminar cell output synapses with specialised postsynaptic densities and a strong bias towards interneurons as targets, including parvalbumin-expressing cells in the CA1 area. (4) Recordings in freely moving rats revealed the network state-dependent segregation of trilaminar cell activity, with reduced firing during movement, but substantial increase in activity with prolonged burst firing (> 200 Hz) during slow wave sleep. We predict that the behaviour-dependent temporal dynamics of trilaminar cell firing are regulated by their specialised inhibitory inputs. Trilaminar cells might support glutamatergic principal cells by disinhibition and mediate the binding of neuronal assemblies between the hippocampus and the subiculum via the transient inhibition of local interneurons.
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Affiliation(s)
- Linda Katona
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK.
| | - Katja Hartwich
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Ryohei Tomioka
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
- Laboratory for Cortical Organization and Systematics, RIKEN Brain Science Institute, Wako, Saitama, 351-0198, Japan
- Department of Morphological Neural Science, Graduate School of Medical Sciences, Kumamoto University, Kumamoto, Japan
| | - Jozsef Somogyi
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - J David B Roberts
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Kristina Wagner
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
| | - Abhilasha Joshi
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK
- Department of Physiology, Kavli Institute for Fundamental Neuroscience, University of California, San Francisco, CA, USA
| | - Thomas Klausberger
- Center for Brain Research, Division of Cognitive Neurobiology, Medical University of Vienna, 1090, Vienna, Austria
| | - Kathleen S Rockland
- Laboratory for Cortical Organization and Systematics, RIKEN Brain Science Institute, Wako, Saitama, 351-0198, Japan
- Department of Anatomy and Neurobiology, Boston University School of Medicine, 72 East Concord St., Boston, MA, 02118, USA
| | - Peter Somogyi
- Department of Pharmacology, University of Oxford, Mansfield Road, Oxford, OX1 3QT, UK.
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Linear and Nonlinear EEG-Based Functional Networks in Anxiety Disorders. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1191:35-59. [PMID: 32002921 DOI: 10.1007/978-981-32-9705-0_3] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Electrocortical network dynamics are integral to brain function. Linear and nonlinear connectivity applications enrich neurophysiological investigations into anxiety disorders. Discrete EEG-based connectivity networks are unfolding with some homogeneity for anxiety disorder subtypes. Attenuated delta/theta/beta connectivity networks, pertaining to anterior-posterior nodes, characterize panic disorder. Nonlinear measures suggest reduced connectivity of ACC as an executive neuro-regulator in germane "fear circuitry networks" might be more central than considered. Enhanced network complexity and theta network efficiency at rest define generalized anxiety disorder, with similar tonic hyperexcitability apparent in social anxiety disorder further extending to task-related/state functioning. Dysregulated alpha connectivity and integration of mPFC-ACC/mPFC-PCC relays implicated with attentional flexibility and choice execution/congruence neurocircuitry are observed in trait anxiety. Conversely, state anxiety appears to recruit converging delta and beta connectivity networks as panic, suggesting trait and state anxiety are modulated by discrete neurobiological mechanisms. Furthermore, EEG connectivity dynamics distinguish anxiety from depression, despite prevalent clinical comorbidity. Rethinking mechanisms implicated in the etiology, maintenance, and treatment of anxiety from the perspective of EEG network science across micro- and macroscales serves to shed light and move the field forward.
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9
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Chauvière L. Update on temporal lobe‐dependent information processing, in health and disease. Eur J Neurosci 2019; 51:2159-2204. [DOI: 10.1111/ejn.14594] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 09/06/2019] [Accepted: 09/27/2019] [Indexed: 01/29/2023]
Affiliation(s)
- Laëtitia Chauvière
- INSERM U1266 Institut de Psychiatrie et de Neurosciences de Paris (IPNP) Paris France
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10
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Koster R, Chadwick MJ, Chen Y, Berron D, Banino A, Düzel E, Hassabis D, Kumaran D. Big-Loop Recurrence within the Hippocampal System Supports Integration of Information across Episodes. Neuron 2019; 99:1342-1354.e6. [PMID: 30236285 DOI: 10.1016/j.neuron.2018.08.009] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2017] [Revised: 02/28/2018] [Accepted: 08/07/2018] [Indexed: 01/07/2023]
Abstract
Recent evidence challenges the widely held view that the hippocampus is specialized for episodic memory, by demonstrating that it also underpins the integration of information across experiences. Contemporary computational theories propose that these two contrasting functions can be accomplished by big-loop recurrence, whereby the output of the system is recirculated back into the hippocampus. We use ultra-high-resolution fMRI to provide support for this hypothesis, by showing that retrieved information is presented as a new input on the superficial entorhinal cortex-driven by functional connectivity between the deep and superficial entorhinal layers. Further, the magnitude of this laminar connectivity correlated with inferential performance, demonstrating its importance for behavior. Our findings offer a novel perspective on information processing within the hippocampus and support a unifying framework in which the hippocampus captures higher-order structure across experiences, by creating a dynamic memory space from separate episodic codes for individual experiences.
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Affiliation(s)
| | | | - Yi Chen
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke-University Magdeburg, 39120 Magdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE), Site Magdeburg, 39120 Magdeburg, Germany
| | - David Berron
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke-University Magdeburg, 39120 Magdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE), Site Magdeburg, 39120 Magdeburg, Germany; Clinical Memory Research Unit, Department of Clinical Sciences Malmö, Lund University, 223 62 Lund, Sweden
| | | | - Emrah Düzel
- Institute of Cognitive Neurology and Dementia Research, Otto-von-Guericke-University Magdeburg, 39120 Magdeburg, Germany; German Center for Neurodegenerative Diseases (DZNE), Site Magdeburg, 39120 Magdeburg, Germany; Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AR, UK
| | - Demis Hassabis
- DeepMind, 5 New Street Square, London EC4A 3TW, UK; Gatsby Computational Neuroscience Unit, 25 Howland Street, London W1T 4JG, UK
| | - Dharshan Kumaran
- DeepMind, 5 New Street Square, London EC4A 3TW, UK; Institute of Cognitive Neuroscience, University College London, 17 Queen Square, London WC1N 3AR, UK.
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Effects of Inducing Gamma Oscillations in Hippocampal Subregions DG, CA3, and CA1 on the Potential Alleviation of Alzheimer's Disease-Related Pathology: Computer Modeling and Simulations. ENTROPY 2019; 21:e21060587. [PMID: 33267301 PMCID: PMC7515076 DOI: 10.3390/e21060587] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Revised: 06/11/2019] [Accepted: 06/11/2019] [Indexed: 12/02/2022]
Abstract
The aim of this study was to evaluate the possibility of the gamma oscillation function (40–130 Hz) to reduce Alzheimer’s disease related pathology in a computer model of the hippocampal network dentate gyrus, CA3, and CA1 (DG-CA3-CA1) regions. Methods: Computer simulations were made for a pathological model in which Alzheimer’s disease was simulated by synaptic degradation in the hippocampus. Pathology modeling was based on sequentially turning off the connections with entorhinal cortex layer 2 (EC2) and the dentate gyrus on CA3 pyramidal neurons. Gamma induction modeling consisted of simulating the oscillation provided by the septo-hippocampal pathway with band frequencies from 40–130 Hz. Pathological models with and without gamma induction were compared with a control. Results: In the hippocampal regions of DG, CA3, and CA1, and jointly DG-CA3-CA1 and CA3-CA1, gamma induction resulted in a statistically significant improvement in terms of increased numbers of spikes, spikes per burst, and burst duration as compared with the model simulating Alzheimer’s disease (AD). The positive maximal Lyapunov exponent was negative in both the control model and the one with gamma induction as opposed to the pathological model where it was positive within the DG-CA3-CA1 region. Gamma induction resulted in decreased transfer entropy in accordance with the information flow in DG → CA3 and CA3 → CA1. Conclusions: The results of simulation studies show that inducing gamma oscillations in the hippocampus may reduce Alzheimer’s disease related pathology. Pathologically higher transfer entropy values after gamma induction returned to values comparable to the control model.
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Świetlik D, Białowąs J, Moryś J, Klejbor I, Kusiak A. Computer Modeling of Alzheimer's Disease-Simulations of Synaptic Plasticity and Memory in the CA3-CA1 Hippocampal Formation Microcircuit. Molecules 2019; 24:E1909. [PMID: 31108977 PMCID: PMC6571632 DOI: 10.3390/molecules24101909] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 05/12/2019] [Accepted: 05/16/2019] [Indexed: 12/19/2022] Open
Abstract
This paper aims to present computer modeling of synaptic plasticity and memory in the CA3-CA1 hippocampal formation microcircuit. The computer simulations showed a comparison of a pathological model in which Alzheimer's disease (AD) was simulated by synaptic degradation in the hippocampus and control model (healthy) of CA3-CA1 networks with modification of weights for the memory. There were statistically higher spike values of both CA1 and CA3 pyramidal cells in the control model than in the pathological model (p = 0.0042 for CA1 and p = 0.0033 for CA3). A similar outcome was achieved for frequency (p = 0.0002 for CA1 and p = 0.0001 for CA3). The entropy of pyramidal cells of the healthy CA3 network seemed to be significantly higher than that of AD (p = 0.0304). We need to study a lot of physiological parameters and their combinations of the CA3-CA1 hippocampal formation microcircuit to understand AD. High statistically correlations were obtained between memory, spikes and synaptic deletion in both CA1 and CA3 cells.
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Affiliation(s)
- Dariusz Świetlik
- Intrafaculty College of Medical Informatics and Biostatistics, Medical University of Gdańsk, 1 Debinki St., 80-211 Gdańsk, Poland.
| | - Jacek Białowąs
- Department of Anatomy and Neurobiology, Medical University of Gdańsk, 1 Debinki St., 80-211 Gdańsk, Poland.
| | - Janusz Moryś
- Department of Anatomy and Neurobiology, Medical University of Gdańsk, 1 Debinki St., 80-211 Gdańsk, Poland.
| | - Ilona Klejbor
- Department of Anatomy and Neurobiology, Medical University of Gdańsk, 1 Debinki St., 80-211 Gdańsk, Poland.
| | - Aida Kusiak
- Department of Periodontology and Oral Mucosa Diseases, Medical University of Gdańsk, 1a Debowa St., 80-204 Gdańsk, Poland.
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Computer Model of Synapse Loss During an Alzheimer's Disease-Like Pathology in Hippocampal Subregions DG, CA3 and CA1-The Way to Chaos and Information Transfer. ENTROPY 2019; 21:e21040408. [PMID: 33267122 PMCID: PMC7514896 DOI: 10.3390/e21040408] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/04/2019] [Revised: 04/14/2019] [Accepted: 04/16/2019] [Indexed: 01/26/2023]
Abstract
The aim of the study was to compare the computer model of synaptic breakdown in an Alzheimer’s disease-like pathology in the dentate gyrus (DG), CA3 and CA1 regions of the hippocampus with a control model using neuronal parameters and methods describing the complexity of the system, such as the correlative dimension, Shannon entropy and positive maximal Lyapunov exponent. The model of synaptic breakdown (from 13% to 50%) in the hippocampus modeling the dynamics of an Alzheimer’s disease-like pathology was simulated. Modeling consisted in turning off one after the other EC2 connections and connections from the dentate gyrus on the CA3 pyramidal neurons. The pathological model of synaptic disintegration was compared to a control. The larger synaptic breakdown was associated with a statistically significant decrease in the number of spikes (R = −0.79, P < 0.001), spikes per burst (R = −0.76, P < 0.001) and burst duration (R = −0.83, P < 0.001) and an increase in the inter-burst interval (R = 0.85, P < 0.001) in DG-CA3-CA1. The positive maximal Lyapunov exponent in the control model was negative, but in the pathological model had a positive value of DG-CA3-CA1. A statistically significant decrease of Shannon entropy with the direction of information flow DG->CA3->CA1 (R = −0.79, P < 0.001) in the pathological model and a statistically significant increase with greater synaptic breakdown (R = 0.24, P < 0.05) of the CA3-CA1 region was obtained. The reduction of entropy transfer for DG->CA3 at the level of synaptic breakdown of 35% was 35%, compared with the control. Entropy transfer for CA3->CA1 at the level of synaptic breakdown of 35% increased to 95% relative to the control. The synaptic breakdown model in an Alzheimer’s disease-like pathology in DG-CA3-CA1 exhibits chaotic features as opposed to the control. Synaptic breakdown in which an increase of Shannon entropy is observed indicates an irreversible process of Alzheimer’s disease. The increase in synapse loss resulted in decreased information flow and entropy transfer in DG->CA3, and at the same time a strong increase in CA3->CA1.
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Vieweg P, Riemer M, Berron D, Wolbers T. Memory Image Completion: Establishing a task to behaviorally assess pattern completion in humans. Hippocampus 2019; 29:340-351. [PMID: 30246900 PMCID: PMC6519020 DOI: 10.1002/hipo.23030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2018] [Revised: 08/15/2018] [Accepted: 09/13/2018] [Indexed: 11/06/2022]
Abstract
For memory retrieval, pattern completion is a crucial process that restores memories from partial or degraded cues. Neurocognitive aging models suggest that the aged memory system is biased toward pattern completion, resulting in a behavioral preference for retrieval over encoding of memories. Here, we built on our previously developed behavioral recognition memory paradigm-the Memory Image Completion (MIC) task-a task to specifically target pattern completion. First, we used the original design with concurrent eye-tracking in order to rule out perceptual confounds that could interact with recognition performance. Second, we developed parallel versions of the task to accommodate test settings in clinical environments or longitudinal studies. The results show that older adults have a deficit in pattern completion ability with a concurrent bias toward pattern completion. Importantly, eye-tracking data during encoding could not account for age-related performance differences. At retrieval, spatial viewing patterns for both age groups were more driven by stimulus identity than by response choice, but compared to young adults, older adults' fixation patterns overlapped more between stimuli that they (wrongly) thought had the same identity. This supports the observation that older adults choose responses perceived as similar to a learned stimulus, indicating a bias toward pattern completion. Additionally, two shorter versions of the task yielded comparable results, and no general learning effects were observed for repeated testing. Together, we present evidence that the MIC is a reliable behavioral task that targets pattern completion, that is easily and repeatedly applicable, and that is made freely available online.
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Affiliation(s)
- Paula Vieweg
- Institute of Psychology, University of LeipzigLeipzigGermany
- German Center for Neurodegenerative Diseases (DZNE)MagdeburgGermany
| | - Martin Riemer
- German Center for Neurodegenerative Diseases (DZNE)MagdeburgGermany
- Medical Faculty, University Hospital Magdeburg (FME)Otto von Guericke University MagdeburgMagdeburgGermany
- Center for Behavioral Brain SciencesMagdeburgGermany
| | - David Berron
- German Center for Neurodegenerative Diseases (DZNE)MagdeburgGermany
- Institute of Cognitive Neurology and Dementia Research, Otto von Guericke University MagdeburgMagdeburgGermany
- Clinical Memory Research Unit, Department of Clinical Sciences MalmöLund UniversityLundSweden
| | - Thomas Wolbers
- German Center for Neurodegenerative Diseases (DZNE)MagdeburgGermany
- Medical Faculty, University Hospital Magdeburg (FME)Otto von Guericke University MagdeburgMagdeburgGermany
- Center for Behavioral Brain SciencesMagdeburgGermany
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15
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Abichou K, La Corte V, Hubert N, Orriols E, Gaston-Bellegarde A, Nicolas S, Piolino P. Young and Older Adults Benefit From Sleep, but Not From Active Wakefulness for Memory Consolidation of What-Where-When Naturalistic Events. Front Aging Neurosci 2019; 11:58. [PMID: 30949043 PMCID: PMC6435496 DOI: 10.3389/fnagi.2019.00058] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 02/28/2019] [Indexed: 11/13/2022] Open
Abstract
An extensive psychological literature shows that sleep actively promotes human episodic memory (EM) consolidation in younger adults. However, evidence for the benefit of sleep for EM consolidation in aging is still elusive. In addition, most of the previous studies used EM assessments that are very different from everyday life conditions and are far from considering all the hallmarks of this memory system. In this study, the effect of an extended period of sleep was compared to the effect of an extended period of active wakefulness on the EM consolidation of naturalistic events, using a novel (What-Where-When) EM task, rich in perceptual details and spatio-temporal context, presented in a virtual environment. We investigated the long-term What-Where-When and Details binding performances of young and elderly people before and after an interval of sleep or active wakefulness. Although we found a noticeable age-related decline in EM, both age groups benefited from sleep, but not from active wakefulness. In younger adults, only the period of sleep significantly enhanced the capacity to associate different components of EM (binding performance) and more specifically the free recall of what-when information. Interestingly, in the elderly, sleep significantly enhanced not only the recall of factual elements but also associated details and contextual information as well as the amount of high feature binding (i.e., What-Where-When and Details). Thus, this study evidences the benefit of sleep, and the detrimental effect of active wakefulness, on long-term feature binding, which is one of the core characteristics of EM, and its effectiveness in normal aging. However, further research should investigate whether this benefit is specific to sleep or more generally results from the effect of a post-learning period of reduced interference, which could also concern quiet wakefulness.
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Affiliation(s)
- Kouloud Abichou
- Laboratoire Mémoire Cerveau et Cognition (MC2Lab EA 7536), Institut de Psychologie, Université Sorbonne Paris Cité, Boulogne-Billancourt, France
| | - Valentina La Corte
- Laboratoire Mémoire Cerveau et Cognition (MC2Lab EA 7536), Institut de Psychologie, Université Sorbonne Paris Cité, Boulogne-Billancourt, France.,Institute of Memory and Alzheimer's Disease, Department of Neurology, Pitié-Salpêtrière Hospital, Paris, France
| | - Nicolas Hubert
- Laboratoire Mémoire Cerveau et Cognition (MC2Lab EA 7536), Institut de Psychologie, Université Sorbonne Paris Cité, Boulogne-Billancourt, France
| | - Eric Orriols
- Laboratoire Mémoire Cerveau et Cognition (MC2Lab EA 7536), Institut de Psychologie, Université Sorbonne Paris Cité, Boulogne-Billancourt, France
| | - Alexandre Gaston-Bellegarde
- Laboratoire Mémoire Cerveau et Cognition (MC2Lab EA 7536), Institut de Psychologie, Université Sorbonne Paris Cité, Boulogne-Billancourt, France
| | - Serge Nicolas
- Laboratoire Mémoire Cerveau et Cognition (MC2Lab EA 7536), Institut de Psychologie, Université Sorbonne Paris Cité, Boulogne-Billancourt, France.,Institut Universitaire de France, Paris, France
| | - Pascale Piolino
- Laboratoire Mémoire Cerveau et Cognition (MC2Lab EA 7536), Institut de Psychologie, Université Sorbonne Paris Cité, Boulogne-Billancourt, France.,Institut Universitaire de France, Paris, France
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16
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Jung MW, Lee H, Jeong Y, Lee JW, Lee I. Remembering rewarding futures: A simulation-selection model of the hippocampus. Hippocampus 2018; 28:913-930. [PMID: 30155938 PMCID: PMC6587829 DOI: 10.1002/hipo.23023] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Revised: 07/06/2018] [Accepted: 08/23/2018] [Indexed: 02/06/2023]
Abstract
Despite tremendous progress, the neural circuit dynamics underlying hippocampal mnemonic processing remain poorly understood. We propose a new model for hippocampal function-the simulation-selection model-based on recent experimental findings and neuroecological considerations. Under this model, the mammalian hippocampus evolved to simulate and evaluate arbitrary navigation sequences. Specifically, we suggest that CA3 simulates unexperienced navigation sequences in addition to remembering experienced ones, and CA1 selects from among these CA3-generated sequences, reinforcing those that are likely to maximize reward during offline idling states. High-value sequences reinforced in CA1 may allow flexible navigation toward a potential rewarding location during subsequent navigation. We argue that the simulation-selection functions of the hippocampus have evolved in mammals mostly because of the unique navigational needs of land mammals. Our model may account for why the mammalian hippocampus has evolved not only to remember, but also to imagine episodes, and how this might be implemented in its neural circuits.
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Affiliation(s)
- Min Whan Jung
- Center for Synaptic Brain Dysfunctions, Institute for Basic ScienceDaejeonSouth Korea
- Department of Biological SciencesKorea Advanced Institute of Science and TechnologyDaejeonSouth Korea
| | - Hyunjung Lee
- Department of AnatomyKyungpook National University School of MedicineDaeguSouth Korea
| | - Yeongseok Jeong
- Center for Synaptic Brain Dysfunctions, Institute for Basic ScienceDaejeonSouth Korea
- Department of Biological SciencesKorea Advanced Institute of Science and TechnologyDaejeonSouth Korea
| | - Jong Won Lee
- Center for Synaptic Brain Dysfunctions, Institute for Basic ScienceDaejeonSouth Korea
| | - Inah Lee
- Department of Brain and Cognitive SciencesSeoul National UniversitySeoulSouth Korea
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17
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BDNF effects on dendritic spine morphology and hippocampal function. Cell Tissue Res 2018; 373:729-741. [DOI: 10.1007/s00441-017-2782-x] [Citation(s) in RCA: 76] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2017] [Accepted: 12/22/2017] [Indexed: 12/22/2022]
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18
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Sans-Dublanc A, Mas-Herrero E, Marco-Pallarés J, Fuentemilla L. Distinct Neurophysiological Mechanisms Support the Online Formation of Individual and Across-Episode Memory Representations. Cereb Cortex 2017; 27:4314-4325. [PMID: 27522079 DOI: 10.1093/cercor/bhw231] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2016] [Accepted: 07/08/2016] [Indexed: 11/12/2022] Open
Abstract
Individual experiences often overlap in their content, presenting opportunities for rapid generalization across them. In this study, we show in 2 independent experiments that integrative encoding-the ability to form individual and across memory representations during online encoding-is supported by 2 distinct neurophysiological responses. Brain potential is increased gradually during encoding and fit to a trial level memory measure for individual episodes, whereas neural oscillations in the theta range (4-6 Hz) emerge later during learning and predict participants' generalization performance in a subsequent test. These results suggest that integrative encoding requires the recruitment of 2 separate neural mechanisms that, despite their co-occurrence in time, differ in their underlying neural dynamics, reflect different brain learning rates and are supportive of the formation of opposed memory representations, individual versus across-event episodes.
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Affiliation(s)
- A Sans-Dublanc
- Cognition and Brain Plasticity Group, Institute of Biomedicine Research of Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, 08908, Spain
| | - E Mas-Herrero
- Cognition and Brain Plasticity Group, Institute of Biomedicine Research of Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, 08908, Spain.,Montreal Neurological Institute - McGill University, Montreal, QC H3A 2B4, Canada
| | - J Marco-Pallarés
- Cognition and Brain Plasticity Group, Institute of Biomedicine Research of Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, 08908, Spain.,Department of Cognitive, Education and Evolutive Psychology, University of Barcelona, Barcelona, 08035, Spain.,Institute of Neurosciences, University of Barcelona, Barcelona, 08035, Spain
| | - L Fuentemilla
- Cognition and Brain Plasticity Group, Institute of Biomedicine Research of Bellvitge (IDIBELL), L'Hospitalet de Llobregat, Barcelona, 08908, Spain.,Department of Cognitive, Education and Evolutive Psychology, University of Barcelona, Barcelona, 08035, Spain.,Institute of Neurosciences, University of Barcelona, Barcelona, 08035, Spain
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19
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Roy DS, Kitamura T, Okuyama T, Ogawa SK, Sun C, Obata Y, Yoshiki A, Tonegawa S. Distinct Neural Circuits for the Formation and Retrieval of Episodic Memories. Cell 2017; 170:1000-1012.e19. [PMID: 28823555 PMCID: PMC5586038 DOI: 10.1016/j.cell.2017.07.013] [Citation(s) in RCA: 181] [Impact Index Per Article: 22.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 03/01/2017] [Accepted: 07/12/2017] [Indexed: 01/26/2023]
Abstract
The formation and retrieval of a memory is thought to be accomplished by activation and reactivation, respectively, of the memory-holding cells (engram cells) by a common set of neural circuits, but this hypothesis has not been established. The medial temporal-lobe system is essential for the formation and retrieval of episodic memory for which individual hippocampal subfields and entorhinal cortex layers contribute by carrying out specific functions. One subfield whose function is poorly known is the subiculum. Here, we show that dorsal subiculum and the circuit, CA1 to dorsal subiculum to medial entorhinal cortex layer 5, play a crucial role selectively in the retrieval of episodic memories. Conversely, the direct CA1 to medial entorhinal cortex layer 5 circuit is essential specifically for memory formation. Our data suggest that the subiculum-containing detour loop is dedicated to meet the requirements associated with recall such as rapid memory updating and retrieval-driven instinctive fear responses.
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Affiliation(s)
- Dheeraj S Roy
- RIKEN-MIT Center for Neural Circuit Genetics at the Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Takashi Kitamura
- RIKEN-MIT Center for Neural Circuit Genetics at the Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Teruhiro Okuyama
- RIKEN-MIT Center for Neural Circuit Genetics at the Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sachie K Ogawa
- RIKEN-MIT Center for Neural Circuit Genetics at the Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Chen Sun
- RIKEN-MIT Center for Neural Circuit Genetics at the Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yuichi Obata
- RIKEN BioResource Center, 3-1-1 Koyadai, Ibaraki 305-0074, Japan
| | - Atsushi Yoshiki
- RIKEN BioResource Center, 3-1-1 Koyadai, Ibaraki 305-0074, Japan
| | - Susumu Tonegawa
- RIKEN-MIT Center for Neural Circuit Genetics at the Picower Institute for Learning and Memory, Department of Biology and Department of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; RIKEN Brain Science Institute, 2-1 Hirosawa, Wako-shi, Saitama 351-0198, Japan.
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20
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Katona L, Micklem B, Borhegyi Z, Swiejkowski DA, Valenti O, Viney TJ, Kotzadimitriou D, Klausberger T, Somogyi P. Behavior-dependent activity patterns of GABAergic long-range projecting neurons in the rat hippocampus. Hippocampus 2017; 27:359-377. [PMID: 27997999 PMCID: PMC5363363 DOI: 10.1002/hipo.22696] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/12/2016] [Indexed: 11/10/2022]
Abstract
Long-range glutamatergic and GABAergic projections participate in temporal coordination of neuronal activity in distributed cortical areas. In the hippocampus, GABAergic neurons project to the medial septum and retrohippocampal areas. Many GABAergic projection cells express somatostatin (SOM+) and, together with locally terminating SOM+ bistratified and O-LM cells, contribute to dendritic inhibition of pyramidal cells. We tested the hypothesis that diversity in SOM+ cells reflects temporal specialization during behavior using extracellular single cell recording and juxtacellular neurobiotin-labeling in freely moving rats. We have demonstrated that rare GABAergic projection neurons discharge rhythmically and are remarkably diverse. During sharp wave-ripples, most projection cells, including a novel SOM+ GABAergic back-projecting cell, increased their activity similar to bistratified cells, but unlike O-LM cells. During movement, most projection cells discharged along the descending slope of theta cycles, but some fired at the trough jointly with bistratified and O-LM cells. The specialization of hippocampal SOM+ projection neurons complements the action of local interneurons in differentially phasing inputs from the CA3 area to CA1 pyramidal cell dendrites during sleep and wakefulness. Our observations suggest that GABAergic projection cells mediate the behavior- and network state-dependent binding of neuronal assemblies amongst functionally-related brain regions by transmitting local rhythmic entrainment of neurons in CA1 to neuronal populations in other areas. © 2016 The Authors Hippocampus Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Linda Katona
- Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3QTUK
- MRC Anatomical Neuropharmacology Unit, Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3THUK
- MRC Brain Network Dynamics Unit, Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3THUK
| | - Ben Micklem
- MRC Anatomical Neuropharmacology Unit, Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3THUK
- MRC Brain Network Dynamics Unit, Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3THUK
| | - Zsolt Borhegyi
- Center for Brain Research, Medical University of ViennaViennaA‐1090Austria
- Department of BiochemistryEötvös Loránd UniversityBudapest1117Hungary
| | - Daniel A. Swiejkowski
- MRC Anatomical Neuropharmacology Unit, Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3THUK
| | - Ornella Valenti
- Center for Brain Research, Medical University of ViennaViennaA‐1090Austria
- Department of Neurophysiology and NeuropharmacologyCenter for Physiology and Pharmacology, Medical University of ViennaVienna1090Austria
| | - Tim J. Viney
- Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3QTUK
- MRC Anatomical Neuropharmacology Unit, Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3THUK
- MRC Brain Network Dynamics Unit, Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3THUK
| | - Dimitrios Kotzadimitriou
- MRC Anatomical Neuropharmacology Unit, Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3THUK
| | - Thomas Klausberger
- MRC Anatomical Neuropharmacology Unit, Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3THUK
- Center for Brain Research, Medical University of ViennaViennaA‐1090Austria
| | - Peter Somogyi
- Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3QTUK
- MRC Anatomical Neuropharmacology Unit, Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3THUK
- MRC Brain Network Dynamics Unit, Department of PharmacologyUniversity of OxfordMansfield RoadOxfordOX1 3THUK
- Center for Brain Research, Medical University of ViennaViennaA‐1090Austria
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21
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Aylar MF, Firouzi F, Araghi MR. Influence of time restriction, 20 minutes and 94.6 months, of visual information on angular displacement during the sit-to-stand (STS) task in three planes. J Phys Ther Sci 2017; 28:3330-3336. [PMID: 28174446 PMCID: PMC5276755 DOI: 10.1589/jpts.28.3330] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2016] [Accepted: 08/09/2016] [Indexed: 11/29/2022] Open
Abstract
[Purpose] The purpose of this investigation was to assess whether or not restriction of
visual information influences the kinematics of sit-to-stand (STS) performance in
children. [Subjects and Methods] Five girls with congenital blindness (CB) and ten healthy
girls with no visual impairments were randomly selected. The girls with congenital
blindness were placed in one group and the ten girls with no visual impairments were
divided into two groups of five, control and treatment groups. The participants in the
treatment group were asked to close their eyes (EC) for 20 minutes before the STS test,
whereas those in the control group kept their eyes open (EO). The performance of the
participants in all three groups was measured using a motion capture system and two force
plates. [Results] The results show that the constraint duration of visual sensory
information affected the range of motion (ROM), the excursion of the dominant side ankle,
and the ROM of the dominant side knee in the EC group. However, only ankle excursion on
the non-dominant side was affected in the CB group, and this was only observed in the
sagittal plane. [Conclusion] These results indicate that visual memory does not affect the
joint angles in the frontal and transverse planes. Moreover, all of the participants could
perform the STS transition without falling, indicating; the participants performed the STS
maneuver correctly in all planes except the sagittal one.
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Affiliation(s)
- Mozhgan Faraji Aylar
- Faculty of Engineering, Electrical Engineering Department, Imam Reza International University, Iran
| | - Faramarz Firouzi
- Faculty of Engineering, Department of Biomedical Engineering, Mashhad Branch, Islamic Azad University, Iran
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Shibata K, Sasaki Y, Bang JW, Walsh EG, Machizawa MG, Tamaki M, Chang LH, Watanabe T. Overlearning hyperstabilizes a skill by rapidly making neurochemical processing inhibitory-dominant. Nat Neurosci 2017; 20:470-475. [PMID: 28135242 PMCID: PMC5323354 DOI: 10.1038/nn.4490] [Citation(s) in RCA: 120] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2016] [Accepted: 01/04/2017] [Indexed: 12/17/2022]
Abstract
Overlearning refers to the continued training of a skill after performance improvement has plateaued. Whether overlearning is beneficial is a question in our daily lives that has never been clearly answered. Here, we report a new important role: Overlearning abruptly changes neurochemical processing to hyper-stabilize and protect trained perceptual learning from subsequent new learning. Usually, learning immediately after training is so unstable that it can be disrupted by subsequent new learning, unless waiting for passive stabilization, which takes hours. However, overlearning so rapidly and strongly stabilizes the learning state that it not only becomes resilient against, but disrupts, subsequent new learning. Such hyper-stabilization is associated with an abrupt shift from glutamate-dominant excitatory to gamma-aminobutyric-acid-dominant inhibitory processing in early visual areas. Hyper-stabilization contrasts with passive and slower stabilization, which is associated with a mere reduction of an excitatory dominance to baseline levels. Utilizing hyper-stabilization may lead to efficient learning paradigms.
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Affiliation(s)
- Kazuhisa Shibata
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA.,Graduate School of Environmental Studies, Nagoya University, Nagoya, Japan
| | - Yuka Sasaki
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA
| | - Ji Won Bang
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA
| | - Edward G Walsh
- Department of Neuroscience, Brown University, Providence, Rhode Island, USA
| | - Maro G Machizawa
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA
| | - Masako Tamaki
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA
| | - Li-Hung Chang
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA
| | - Takeo Watanabe
- Department of Cognitive, Linguistics, &Psychological Sciences, Brown University, Providence, Rhode Island, USA
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23
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Lebois EP, Trimper JB, Hu C, Levey AI, Manns JR. Effects of Selective M 1 Muscarinic Receptor Activation on Hippocampal Spatial Representations and Neuronal Oscillations. ACS Chem Neurosci 2016; 7:1393-1405. [PMID: 27479319 DOI: 10.1021/acschemneuro.6b00160] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The muscarinic M1 acetylcholine receptor is a key target for drugs aimed at treating cognitive dysfunction, including the memory impairment in Alzheimer's disease. The overall question of the current study was to ask how systemic administration of the bitopic M1 agonist VU0364572, the M1 positive allosteric modulator BQCA, and the acetylcholinesterase inhibitor donepezil (current standard of care for Alzheimer's disease), would impact spatial memory-related hippocampal function in rats. Hippocampal pyramidal neuron spiking and local field potentials were recorded from regions CA1 and CA3 as rats freely foraged in a recording enclosure. To assess the relative stability versus flexibility of the rats' spatial representations, the walls of the recording enclosure were reshaped in 15-m intervals. As compared to the control condition, systemic administration of VU0364572 increased spatial correlations of CA1 and CA3 pyramidal neuron spiking across all enclosure shape comparisons, whereas BQCA and donepezil appeared to decrease these spatial correlations. Further, both VU0364572 and BQCA increased intrahippocampal synchrony as measured by CA3-CA1 field-field coherence in frequency ranges that tended to align with the prominence of those oscillations for the behavioral state (i.e., theta during locomotion and slow gamma during stationary moments). The results indicated that VU0364572 and BQCA influenced hippocampal function differently but in ways that might both be beneficial for treating memory dysfunction.
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Affiliation(s)
- Evan P. Lebois
- Neuroscience Graduate Program, ‡Department of Psychology, §Neuroscience and Behavioral Biology
Program, and ∥Department of Neurology, Emory University, Atlanta, Georgia, 30322, United States
| | - John B. Trimper
- Neuroscience Graduate Program, ‡Department of Psychology, §Neuroscience and Behavioral Biology
Program, and ∥Department of Neurology, Emory University, Atlanta, Georgia, 30322, United States
| | - Chun Hu
- Neuroscience Graduate Program, ‡Department of Psychology, §Neuroscience and Behavioral Biology
Program, and ∥Department of Neurology, Emory University, Atlanta, Georgia, 30322, United States
| | - Allan I. Levey
- Neuroscience Graduate Program, ‡Department of Psychology, §Neuroscience and Behavioral Biology
Program, and ∥Department of Neurology, Emory University, Atlanta, Georgia, 30322, United States
| | - Joseph R. Manns
- Neuroscience Graduate Program, ‡Department of Psychology, §Neuroscience and Behavioral Biology
Program, and ∥Department of Neurology, Emory University, Atlanta, Georgia, 30322, United States
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24
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Viskontas IV, Knowlton BJ, Fried I. Responses of neurons in the medial temporal lobe during encoding and recognition of face-scene pairs. Neuropsychologia 2016; 90:200-9. [PMID: 27424273 DOI: 10.1016/j.neuropsychologia.2016.07.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2016] [Revised: 07/09/2016] [Accepted: 07/12/2016] [Indexed: 11/30/2022]
Abstract
Associations between co-occurring stimuli are formed in the medial temporal lobe (MTL). Here, we recorded from 508 single and multi-units in the MTL while participants learned and retrieved associations between unfamiliar faces and unfamiliar scenes. Participant's memories for the face-scene pairs were later tested using cued recall and recognition tests. The results show that neurons in the parahippocampal cortex are most likely to respond with changes from baseline firing to these stimuli during both encoding and recognition, and this region showed the greatest proportion of cells showing differential responses depending on the phase of the task. Furthermore, we found that cells in the parahippocampal cortex that responded during both encoding and recognition were more likely to show decreases from baseline firing than cells that were only recruited during recognition, which were more likely to show increases in firing. Since all stimuli shown during recognition were familiar to the patients, these findings suggest that with familiarity, cell responses become more sharply tuned. No neurons in this region, however, were found to be affected by recombining face/scene pairs. Neurons in other MTL regions, particularly the hippocampus, were sensitive to stimulus configurations. Thus, the results support the idea that neurons in the parahippocampal cortex code for features of stimuli and neurons in the hippocampus are more likely to represent their specific configurations.
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Affiliation(s)
- Indre V Viskontas
- Department of Psychology, UCLA, Los Angeles, CA 90095, United States
| | | | - Itzhak Fried
- Department of Neurosurgery, UCLA, Los Angeles, CA 90095, United States
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Madhavadas S, Subramanian S. Cognition enhancing effect of the aqueous extract ofCinnamomum zeylanicumon non-transgenic Alzheimer's disease rat model: Biochemical, histological, and behavioural studies. Nutr Neurosci 2016; 20:526-537. [DOI: 10.1080/1028415x.2016.1194593] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Affiliation(s)
- Sowmya Madhavadas
- Department of Neurochemistry, National Institute of Mental Health and Neurosciences, Bangalore 560 029, India
| | - Sarada Subramanian
- Department of Neurochemistry, National Institute of Mental Health and Neurosciences, Bangalore 560 029, India
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Sarkis RA, Alam J, Pavlova MK, Dworetzky BA, Pennell PB, Stickgold R, Bubrick EJ. Sleep-dependent memory consolidation in the epilepsy monitoring unit: A pilot study. Clin Neurophysiol 2016; 127:2785-2790. [PMID: 27417054 DOI: 10.1016/j.clinph.2016.05.275] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Revised: 05/20/2016] [Accepted: 05/23/2016] [Indexed: 10/21/2022]
Abstract
OBJECTIVE We sought to examine whether patients with focal epilepsy exhibit sleep dependent memory consolidation, whether memory retention rates correlated with particular aspects of sleep physiology, and how the process was affected by seizures. METHODS We prospectively recruited patients with focal epilepsy and assessed declarative memory using a task consisting of 15 pairs of colored pictures on a 5×6 grid. Patients were tested 12h after training, once after 12h of wakefulness and once after 12h that included sleep. EMG chin electrodes were placed to enable sleep scoring. The number and density of sleep spindles were assessed using a wavelet-based algorithm. RESULTS Eleven patients were analyzed age 21-56years. The percentage memory retention over 12h of wakefulness was 62.7% and over 12h which included sleep 83.6% (p=0.04). Performance on overnight testing correlated with the duration of slow wave sleep (SWS) (r=+0.63, p<0.05). Three patients had seizures during the day, and 3 had nocturnal seizures. Day-time seizures did not affect retention rates, while those patients who had night time seizures had a drop in retention from an average of 92% to 60.5%. CONCLUSIONS There is evidence of sleep dependent memory consolidation in patients with epilepsy which mostly correlates with the amount of SWS. Our preliminary findings suggest that nocturnal seizures likely disrupt sleep dependent memory consolidation. SIGNIFICANCE Findings highlight the importance of SWS in sleep dependent memory consolidation and the adverse impact of nocturnal seizures on this process.
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Affiliation(s)
- Rani A Sarkis
- Department of Neurology, Edward B. Bromfield Epilepsy Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA.
| | - Javad Alam
- Department of Neurology, Edward B. Bromfield Epilepsy Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Milena K Pavlova
- Department of Neurology, Edward B. Bromfield Epilepsy Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Barbara A Dworetzky
- Department of Neurology, Edward B. Bromfield Epilepsy Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Page B Pennell
- Department of Neurology, Edward B. Bromfield Epilepsy Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Robert Stickgold
- Department of Psychiatry, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, USA
| | - Ellen J Bubrick
- Department of Neurology, Edward B. Bromfield Epilepsy Center, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
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Abstract
The central point of this article is that the concept of memory as information storage in the brain is inadequate for and irrelevant to understanding the nervous system. Beginning from the sensorimotor hypothesis that underlies neuroscience—that the entire function of the nervous system is to connect experience to appropriate behavior—the paper defines memories as sequences of events that connect remote experience to present behavior. Their essential components are (a) persistent events that bridge the time from remote experience to present behavior and (b) junctional events in which connections from remote experience and recent experience merge to produce behavior. The sequences comprising even the simplest memories are complex. This is both necessary—to preserve previously learned behaviors—and inevitable—due to secondary activity-driven plasticity. This complexity further highlights the inadequacy of the information storage concept and the importance of extreme simplicity in models used to study memory.
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Affiliation(s)
- Jonathan R Wolpaw
- Wadsworth Center, New York State Department of Health, Albany, NY 12201-0509, USA.
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Dokter M, von Bohlen und Halbach O. Neurogenesis within the adult hippocampus under physiological conditions and in depression. Neural Regen Res 2015; 7:552-9. [PMID: 25745444 PMCID: PMC4349005 DOI: 10.3969/j.issn.1673-5374.2012.07.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2011] [Accepted: 02/06/2012] [Indexed: 01/18/2023] Open
Abstract
Adult neurogenesis can only be observed in some specific brain regions. One of these areas is the dentate gyrus of the hippocampal formation. The progenitor cells located in the subgranular layer of the dentate gyrus proliferate, differentiate, and give rise to young neurons that can become integrated into existing neuronal circuits. Under physiological conditions, hippocampal neurogenesis is linked to hippocampal-dependent learning, whereas deficits in adult hippocampal neurogenesis have been shown to correlate with disturbances in spatial learning and memory. This review summarizes the phenomenon of adult hippocampal neurogenesis and the use of suitable markers for the investigation of adult hippocampal neurogenesis. In addition, we focused on the disturbances in neurogenesis that can be seen in depression. Interestingly, several antidepressants have been found to be capable of increasing the rate of hippocampal neurogenesis. Based on that, it can be speculated that factors, which directly or indirectly increase the rate of hippocampal neurogenesis, may be helpful in the treatment of depression.
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Affiliation(s)
- Martin Dokter
- Institute of Anatomy and Cell Biology, Ernst Moritz Arndt University of Greifswald, Germany
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Fiebig F, Lansner A. Memory consolidation from seconds to weeks: a three-stage neural network model with autonomous reinstatement dynamics. Front Comput Neurosci 2014; 8:64. [PMID: 25071536 PMCID: PMC4077014 DOI: 10.3389/fncom.2014.00064] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Accepted: 05/24/2014] [Indexed: 11/29/2022] Open
Abstract
Declarative long-term memories are not created in an instant. Gradual stabilization and temporally shifting dependence of acquired declarative memories in different brain regions-called systems consolidation-can be tracked in time by lesion experiments. The observation of temporally graded retrograde amnesia (RA) following hippocampal lesions points to a gradual transfer of memory from hippocampus to neocortical long-term memory. Spontaneous reactivations of hippocampal memories, as observed in place cell reactivations during slow-wave-sleep, are supposed to drive neocortical reinstatements and facilitate this process. We propose a functional neural network implementation of these ideas and furthermore suggest an extended three-state framework that includes the prefrontal cortex (PFC). It bridges the temporal chasm between working memory percepts on the scale of seconds and consolidated long-term memory on the scale of weeks or months. We show that our three-stage model can autonomously produce the necessary stochastic reactivation dynamics for successful episodic memory consolidation. The resulting learning system is shown to exhibit classical memory effects seen in experimental studies, such as retrograde and anterograde amnesia (AA) after simulated hippocampal lesioning; furthermore the model reproduces peculiar biological findings on memory modulation, such as retrograde facilitation of memory after suppressed acquisition of new long-term memories-similar to the effects of benzodiazepines on memory.
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Affiliation(s)
- Florian Fiebig
- Department of Computational Biology, Royal Institute of Technology (KTH)Stockholm, Sweden
- Institute for Adaptive and Neural Computation, School of Informatics, Edinburgh UniversityEdinburgh, Scotland
| | - Anders Lansner
- Department of Computational Biology, Royal Institute of Technology (KTH)Stockholm, Sweden
- Department of Numerical Analysis and Computer Science, Stockholm UniversityStockholm, Sweden
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Kaplan BA, Lansner A. A spiking neural network model of self-organized pattern recognition in the early mammalian olfactory system. Front Neural Circuits 2014; 8:5. [PMID: 24570657 PMCID: PMC3916767 DOI: 10.3389/fncir.2014.00005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2013] [Accepted: 01/09/2014] [Indexed: 01/01/2023] Open
Abstract
Olfactory sensory information passes through several processing stages before an odor percept emerges. The question how the olfactory system learns to create odor representations linking those different levels and how it learns to connect and discriminate between them is largely unresolved. We present a large-scale network model with single and multi-compartmental Hodgkin-Huxley type model neurons representing olfactory receptor neurons (ORNs) in the epithelium, periglomerular cells, mitral/tufted cells and granule cells in the olfactory bulb (OB), and three types of cortical cells in the piriform cortex (PC). Odor patterns are calculated based on affinities between ORNs and odor stimuli derived from physico-chemical descriptors of behaviorally relevant real-world odorants. The properties of ORNs were tuned to show saturated response curves with increasing concentration as seen in experiments. On the level of the OB we explored the possibility of using a fuzzy concentration interval code, which was implemented through dendro-dendritic inhibition leading to winner-take-all like dynamics between mitral/tufted cells belonging to the same glomerulus. The connectivity from mitral/tufted cells to PC neurons was self-organized from a mutual information measure and by using a competitive Hebbian-Bayesian learning algorithm based on the response patterns of mitral/tufted cells to different odors yielding a distributed feed-forward projection to the PC. The PC was implemented as a modular attractor network with a recurrent connectivity that was likewise organized through Hebbian-Bayesian learning. We demonstrate the functionality of the model in a one-sniff-learning and recognition task on a set of 50 odorants. Furthermore, we study its robustness against noise on the receptor level and its ability to perform concentration invariant odor recognition. Moreover, we investigate the pattern completion capabilities of the system and rivalry dynamics for odor mixtures.
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Affiliation(s)
- Bernhard A Kaplan
- Department of Computational Biology, School of Computer Science and Communication, Royal Institute of Technology Stockholm, Sweden ; Stockholm Brain Institute, Karolinska Institute Stockholm, Sweden
| | - Anders Lansner
- Department of Computational Biology, School of Computer Science and Communication, Royal Institute of Technology Stockholm, Sweden ; Stockholm Brain Institute, Karolinska Institute Stockholm, Sweden ; Department of Numerical Analysis and Computer Science, Stockholm University Stockholm, Sweden
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Recruitment of Perisomatic Inhibition during Spontaneous Hippocampal Activity In Vitro. PLoS One 2013; 8:e66509. [PMID: 23805227 PMCID: PMC3689796 DOI: 10.1371/journal.pone.0066509] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2011] [Accepted: 05/10/2013] [Indexed: 11/19/2022] Open
Abstract
It was recently shown that perisomatic GABAergic inhibitory postsynaptic potentials (IPSPs) originating from basket and chandelier cells can be recorded as population IPSPs from the hippocampal pyramidal layer using extracellular electrodes (eIPSPs). Taking advantage of this approach, we have investigated the recruitment of perisomatic inhibition during spontaneous hippocampal activity in vitro. Combining intracellular and extracellular recordings from pyramidal cells and interneurons, we confirm that inhibitory signals generated by basket cells can be recorded extracellularly, but our results suggest that, during spontaneous activity, eIPSPs are mostly confined to the CA3 rather than CA1 region. CA3 eIPSPs produced the powerful time-locked inhibition of multi-unit activity expected from perisomatic inhibition. Analysis of the temporal dynamics of spike discharges relative to eIPSPs suggests significant but moderate recruitment of excitatory and inhibitory neurons within the CA3 network on a 10 ms time scale, within which neurons recruit each other through recurrent collaterals and trigger powerful feedback inhibition. Such quantified parameters of neuronal interactions in the hippocampal network may serve as a basis for future characterisation of pathological conditions potentially affecting the interactions between excitation and inhibition in this circuit.
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Saraceno C, Musardo S, Marcello E, Pelucchi S, Di Luca M. Modeling Alzheimer's disease: from past to future. Front Pharmacol 2013; 4:77. [PMID: 23801962 PMCID: PMC3685797 DOI: 10.3389/fphar.2013.00077] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2013] [Accepted: 05/30/2013] [Indexed: 12/11/2022] Open
Abstract
Alzheimer’s disease (AD) is emerging as the most prevalent and socially disruptive illness of aging populations, as more people live long enough to become affected. Although AD is placing a considerable and increasing burden on society, it represents the largest unmet medical need in neurology, because current drugs improve symptoms, but do not have profound disease-modifying effects. Although AD pathogenesis is multifaceted and difficult to pinpoint, genetic and cell biological studies led to the amyloid hypothesis, which posits that amyloid β (Aβ) plays a pivotal role in AD pathogenesis. Amyloid precursor protein (APP), as well as β- and γ-secretases are the principal players involved in Aβ production, while α-secretase cleavage on APP prevents Aβ deposition. The association of early onset familial AD with mutations in the APP and γ-secretase components provided a potential tool of generating animal models of the disease. However, a model that recapitulates all the aspects of AD has not yet been produced. Here, we face the problem of modeling AD pathology describing several models, which have played a major role in defining critical disease-related mechanisms and in exploring novel potential therapeutic approaches. In particular, we will provide an extensive overview on the distinct features and pros and contras of different AD models, ranging from invertebrate to rodent models and finally dealing with computational models and induced pluripotent stem cells.
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Affiliation(s)
- Claudia Saraceno
- Dipartimento di Scienze Farmacologiche e Biomolecolari, Università degli Studi di Milano Milano, Italy ; Centre of Excellence on Neurodegenerative Diseases, Università degli Studi di Milano Milano, Italy
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Balderas I, Morin JP, Rodriguez-Ortiz CJ, Bermudez-Rattoni F. Muscarinic receptors activity in the perirhinal cortex and hippocampus has differential involvement in the formation of recognition memory. Neurobiol Learn Mem 2012; 97:418-24. [PMID: 22452926 DOI: 10.1016/j.nlm.2012.03.006] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 03/09/2012] [Accepted: 03/12/2012] [Indexed: 11/17/2022]
Abstract
In this work we probed the effects of post-trial infusions of the muscarinic receptor antagonist scopolamine on object recognition memory formation. Scopolamine was infused bilaterally immediately after the sample phase in the perirhinal cortex or dorsal hippocampus and animals were tested for short-term (90 min) or long-term (24 h) memory. Results showed that scopolamine impaired short-term memory when injected in either the perirhinal cortex or hippocampus. Nevertheless, scopolamine disrupted long-term memory when administrated in the perirhinal cortex but not when applied in the hippocampus. Long-term memory was unaffected when scopolamine was infused 160 min after the sample phase or 90 min before test phase. Our data indicate that short-term recognition memory requires muscarinic receptors signaling in both the perirhinal cortex and hippocampus, whereas long-term recognition memory depends on muscarinic receptors in the perirhinal cortex but not hippocampus. These results support a differential involvement of muscarinic activity in these two medial temporal lobe structures in the formation of recognition memory.
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Affiliation(s)
- Israela Balderas
- División de Neurociencias, Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado Postal 70-253, 04510 México D.F., Mexico.
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Giulioni M, Camilleri P, Mattia M, Dante V, Braun J, Del Giudice P. Robust Working Memory in an Asynchronously Spiking Neural Network Realized with Neuromorphic VLSI. Front Neurosci 2012; 5:149. [PMID: 22347151 PMCID: PMC3270576 DOI: 10.3389/fnins.2011.00149] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2011] [Accepted: 12/29/2011] [Indexed: 11/29/2022] Open
Abstract
We demonstrate bistable attractor dynamics in a spiking neural network implemented with neuromorphic VLSI hardware. The on-chip network consists of three interacting populations (two excitatory, one inhibitory) of leaky integrate-and-fire (LIF) neurons. One excitatory population is distinguished by strong synaptic self-excitation, which sustains meta-stable states of “high” and “low”-firing activity. Depending on the overall excitability, transitions to the “high” state may be evoked by external stimulation, or may occur spontaneously due to random activity fluctuations. In the former case, the “high” state retains a “working memory” of a stimulus until well after its release. In the latter case, “high” states remain stable for seconds, three orders of magnitude longer than the largest time-scale implemented in the circuitry. Evoked and spontaneous transitions form a continuum and may exhibit a wide range of latencies, depending on the strength of external stimulation and of recurrent synaptic excitation. In addition, we investigated “corrupted” “high” states comprising neurons of both excitatory populations. Within a “basin of attraction,” the network dynamics “corrects” such states and re-establishes the prototypical “high” state. We conclude that, with effective theoretical guidance, full-fledged attractor dynamics can be realized with comparatively small populations of neuromorphic hardware neurons.
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Yoon J, Seo Y, Kim J, Lee I. Hippocampus is required for paired associate memory with neither delay nor trial uniqueness. Learn Mem 2011; 19:1-8. [PMID: 22174309 DOI: 10.1101/lm.024554.111] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Cued retrieval of memory is typically examined with delay when testing hippocampal functions, as in delayed matching-to-sample tasks. Equally emphasized in the literature, on the other hand, is the hippocampal involvement in making arbitrary associations. Paired associate memory tasks are widely used for examining this function. However, the two variables (i.e., delay and paired association) were often mixed in paired associate tasks, and this makes it difficult to localize the cognitive source of deficits with hippocampal perturbation. Specifically, a few studies have recently shown that rats can learn arbitrary paired associations between certain locations and nonspatial items (e.g., object or flavor) and later can retrieve the paired location when cued by the item remotely. Such tasks involve both (1) delay between sampling the cue and retrieving the target location and (2) arbitrary association between the cueing object and its paired location. Here, we tested whether delay was necessary in a cued paired associate task by using a task in which no delay existed between object cueing and the choice of its paired associate. Moreover, fixed associative relationships between the cueing objects and their paired locations were repeatedly used, thus involving no trial-unique association. Nevertheless, inactivations of the dorsal hippocampus with muscimol severely disrupted retrieval of paired associates, whereas the same manipulations did not affect discriminating individual objects or locations. The results powerfully demonstrate that the hippocampus is inherently required for retrieving paired associations between objects and places, and that delay and trial uniqueness of the paired associates are not necessarily required.
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Affiliation(s)
- Jinah Yoon
- Department of Brain and Cognitive Sciences, Seoul National University, Gwanak-gu, Seoul 151-742, Korea
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37
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Abstract
We investigated human hippocampal functional connectivity in wakefulness and throughout non-rapid eye movement sleep. Young healthy subjects underwent simultaneous EEG and functional magnetic resonance imaging (fMRI) measurements at 1.5 T under resting conditions in the descent to deep sleep. Continuous 5 min epochs representing a unique sleep stage (i.e., wakefulness, sleep stages 1 and 2, or slow-wave sleep) were extracted. fMRI time series of subregions of the hippocampal formation (HF) (cornu ammonis, dentate gyrus, and subiculum) were extracted based on cytoarchitectonical probability maps. We observed sleep stage-dependent changes in HF functional coupling. The HF was integrated to variable strength in the default mode network (DMN) in wakefulness and light sleep stages but not in slow-wave sleep. The strongest functional connectivity between the HF and neocortex was observed in sleep stage 2 (compared with both slow-wave sleep and wakefulness). We observed a strong interaction of sleep spindle occurrence and HF functional connectivity in sleep stage 2, with increased HF/neocortical connectivity during spindles. Moreover, the cornu ammonis exhibited strongest functional connectivity with the DMN during wakefulness, while the subiculum dominated hippocampal functional connectivity to frontal brain regions during sleep stage 2. Increased connectivity between HF and neocortical regions in sleep stage 2 suggests an increased capacity for possible global information transfer, while connectivity in slow-wave sleep is reflecting a functional system optimal for segregated information reprocessing. Our data may be relevant to differentiating sleep stage-specific contributions to neural plasticity as proposed in sleep-dependent memory consolidation.
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Increased resting-state perfusion after repeated encoding is related to later retrieval of declarative associative memories. PLoS One 2011; 6:e19985. [PMID: 21589884 PMCID: PMC3093410 DOI: 10.1371/journal.pone.0019985] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2010] [Accepted: 04/21/2011] [Indexed: 11/25/2022] Open
Abstract
Electrophysiological studies in animals have shown coordinated reactivation of neuronal ensembles during a restricted time period of behavioral inactivity that immediately followed active encoding. In the present study we directly investigated off-line processing of associative memory formation in the human brain. Subjects' regional cerebral blood flow (rCBF) as a surrogate marker of neural activity during rest was measured by MR-based perfusion imaging in a sample of 14 healthy male subjects prior to (Pre2) and after (Post) extensive learning of 24 face-name associations within a selective reminding task (SR). Results demonstrated significant Post-Pre2 rCBF increases in hippocampal and temporal lobe regions, while in a control comparison of two perfusion scans with no learning task in-between (Pre2-Pre1) no differences in rCBF emerged. Post perfusion scanning was followed by a surprise cued associative recall task from which two types of correctly retrieved names were obtained: older names already correctly retrieved at least once during one of the SR blocks, and recent names acquired during the last SR block immediately prior to the Post scan. In the anterior hippocampus individual perfusion increases were correlated with both correct retrievals of older and recent names. By contrast, older but not recently learned names showed a significant correlation with perfusion increases in the left lateral temporal cortex known to be associated with long-term memory. Recent, but not older names were correlated with dopaminergic midbrain structures reported to contribute to the persistence of memory traces for novel information. Although the direct investigation of off-line memory processing did not permit concomitant experimental control, neither intentional rehearsal, nor substantial variations in subjects' states of alertness appear to contribute to present results. We suggest that the observed rCBF increases might reflect processes that possibly contribute to the long-term persistence of memory traces.
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Kealy J, Commins S. The rat perirhinal cortex: A review of anatomy, physiology, plasticity, and function. Prog Neurobiol 2011; 93:522-48. [DOI: 10.1016/j.pneurobio.2011.03.002] [Citation(s) in RCA: 87] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2010] [Revised: 01/28/2011] [Accepted: 03/10/2011] [Indexed: 11/26/2022]
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Autobiographical memory in temporal lobe epilepsy: role of hippocampal and temporal lateral structures. Epilepsy Behav 2010; 19:365-71. [PMID: 20875774 DOI: 10.1016/j.yebeh.2010.07.012] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/06/2010] [Revised: 07/10/2010] [Accepted: 07/17/2010] [Indexed: 01/26/2023]
Abstract
The present study was aimed at investigating the impact of hippocampal and temporal cortical lesions on remote autobiographical memories in temporal lobe epilepsy (TLE). Episodic specificity, episodic richness, and personal semantic memory from different life periods were assessed using a modified version of the Autobiographical Memory Interview (AMI) (M.D. Kopelman, A.E. Wilson, A. Baddeley, The autobiographical memory interview. Bury St. Edmunds: Thames Valley Test Co.; 1990) in 47 patients with unilateral mesial or lateral TLE and 38 healthy controls. Patients with TLE performed significantly more poorly than controls. Patients with left and right mTLE were equally moderately impaired, but patients with left lateral TLE had the most severe episodic memory deficits, particularly for childhood memories. With respect to personal semantic memory, patients with left TLE were significantly more impaired than those with right TLE, most pronounced for childhood memories. Both autobiographical memory aspects, episodic and personal semantic memory, were significantly intercorrelated, but both did not correlate with anterograde memory, indicating a structural dissociation between both functions.
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Zechel S, Werner S, Unsicker K, von Bohlen und Halbach O. Expression and Functions of Fibroblast Growth Factor 2 (FGF-2) in Hippocampal Formation. Neuroscientist 2010; 16:357-73. [DOI: 10.1177/1073858410371513] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Among the 23 members of the fibroblast growth factor (FGF) family, FGF-2 is the most abundant one in the central nervous system. Its impact on neural cells has been profoundly investigated by in vitro and in vivo studies as well as by gene knockout analyses during the past 2 decades. Key functions of FGF-2 in the nervous system include roles in neurogenesis, promotion of axonal growth, differentiation in development, and maintenance and plasticity in adulthood. From a clinical perspective, its prominent role for the maintenance of lesioned neurons (e.g., ischemia and following transection of fiber tracts) is of particular relevance. In the unlesioned brain, FGF-2 is involved in synaptic plasticity and processes attributed to learning and memory. The focus of this review is on the expression of FGF-2 and its receptors in the hippocampal formation and the physiological and pathophysiological roles of FGF-2 in this region during development and adulthood.
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Affiliation(s)
- Sabrina Zechel
- Division of Molecular Neurobiology, Department of Neuroscience, Karolinska Institute, Stockholm, Sweden
| | - Sandra Werner
- Department of Molecular Embryology, Institute of Anatomy & Cell Biology, University of Freiburg, Freiburg, Germany
| | - Klaus Unsicker
- Department of Molecular Embryology, Institute of Anatomy & Cell Biology, University of Freiburg, Freiburg, Germany
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The stolen memory: a case of transient global amnesia. Biol Psychiatry 2010; 67:e31-2. [PMID: 19640505 DOI: 10.1016/j.biopsych.2009.05.028] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2009] [Revised: 05/29/2009] [Accepted: 05/30/2009] [Indexed: 11/21/2022]
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Braun J, Mattia M. Attractors and noise: twin drivers of decisions and multistability. Neuroimage 2010; 52:740-51. [PMID: 20083212 DOI: 10.1016/j.neuroimage.2009.12.126] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2009] [Accepted: 12/12/2009] [Indexed: 11/17/2022] Open
Abstract
Perceptual decisions are made not only during goal-directed behavior such as choice tasks, but also occur spontaneously while multistable stimuli are being viewed. In both contexts, the formation of a perceptual decision is best captured by noisy attractor dynamics. Noise-driven attractor transitions can accommodate a wide range of timescales and a hierarchical arrangement with "nested attractors" harbors even more dynamical possibilities. The attractor framework seems particularly promising for understanding higher-level mental states that combine heterogeneous information from a distributed set of brain areas.
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Affiliation(s)
- Jochen Braun
- Cognitive Biology Lab, University of Magdeburg, Germany.
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Contribution of neural networks to Alzheimer disease's progression. Brain Res Bull 2009; 80:309-14. [DOI: 10.1016/j.brainresbull.2009.06.006] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2009] [Revised: 06/05/2009] [Accepted: 06/06/2009] [Indexed: 11/21/2022]
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Gilbert PE, Brushfield AM. The role of the CA3 hippocampal subregion in spatial memory: a process oriented behavioral assessment. Prog Neuropsychopharmacol Biol Psychiatry 2009; 33:774-81. [PMID: 19375477 PMCID: PMC2743458 DOI: 10.1016/j.pnpbp.2009.03.037] [Citation(s) in RCA: 118] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2009] [Accepted: 03/30/2009] [Indexed: 10/20/2022]
Abstract
Computational models, behavioral data, and electrophysiological data suggest that the CA3 subregion of the hippocampus may support multiple mnemonic processes critical to the formation and subsequent retrieval of spatial memories. Multiple researchers have proposed that the CA3 subregion contains an autoassociative network in which synaptic connections between CA3 neurons that represent different components of a memory are strengthened via recurrent collateral connections. As a result, it has been suggested that the CA3 autoassociative network may support multiple processes including the formation of spatial arbitrary associations, temporary maintenance of spatial working memory, and spatial pattern completion. In addition, the CA3 subregion has been suggested to be involved in spatial pattern separation. The separation of patterns is hypothesized to be accomplished based on the low probability that any two CA3 neurons will receive mossy-fiber input synapses from a similar subset of dentate gyrus cells. The separation of patterns also may be enhanced by competitive inhibition within CA3 and dentate gyrus. This review will focus on the mnemonic processes supported by CA3 neurons and how these processes may facilitate the encoding and retrieval of spatial information. Although there is growing evidence indicating that the hippocampus plays a role in the processing of nonspatial information as well, the scope of the present review will focus on the role of the CA3 subregion in spatial memory.
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Affiliation(s)
- Paul E Gilbert
- Department of Psychology, San Diego State University, San Diego CA 92182, United States.
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Petrulis A. Neural mechanisms of individual and sexual recognition in Syrian hamsters (Mesocricetus auratus). Behav Brain Res 2009; 200:260-7. [PMID: 19014975 PMCID: PMC2668739 DOI: 10.1016/j.bbr.2008.10.027] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Revised: 10/20/2008] [Accepted: 10/22/2008] [Indexed: 11/27/2022]
Abstract
Recognizing the individual and sexual identities of conspecifics is critical for adaptive social behavior and, in most mammals this information is communicated primarily by chemosensory cues. Due to its heavy reliance on odor cues, we have used the Syrian hamster as our model species for investigating the neural regulation of social recognition. Using lesion, electrophysiological and immunocytochemical techniques, separate neural pathways underlying recognition of individual odors and guidance of sex-typical responses to opposite-sex odors have been identified in both male and female hamsters. Specifically, we have found that recognition of individual odor identity requires olfactory bulb connections to entorhinal cortex (ENT) rather than other chemoreceptive brain regions. This kind of social memory does not appear to require the hippocampus and may, instead, depend on ENT connections with piriform cortex. In contrast, sexual recognition, through either differential investigation or scent marking toward opposite-sex odors, depends on both olfactory and vomeronasal system input to the corticomedial amygdala. Preference for investigating opposite-sex odors requires primarily olfactory input to the medial amygdala (ME) whereas appropriately targeted scent marking responses require vomeronasal input to ME as well as to other structures. Within the ME, the anterior section (MEa) appears important for evaluating or classifying social odors whereas the posterodorsal region (MEpd) may be more involved in generating approach to social odors. Evidence is presented that analysis of social odors may initially be done in MEa and then communicated to MEpd, perhaps through micro-circuits that separately process male and female odors.
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Affiliation(s)
- Aras Petrulis
- Neuroscience Institute, Georgia State University, Atlanta, GA 30302-5030, USA.
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48
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Advances in memory research: single-neuron recordings from the human medial temporal lobe aid our understanding of declarative memory. Curr Opin Neurol 2008; 21:662-8. [DOI: 10.1097/wco.0b013e3283168e03] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
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Shohamy D, Wagner AD. Integrating memories in the human brain: hippocampal-midbrain encoding of overlapping events. Neuron 2008; 60:378-89. [PMID: 18957228 PMCID: PMC2628634 DOI: 10.1016/j.neuron.2008.09.023] [Citation(s) in RCA: 374] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2008] [Revised: 09/19/2008] [Accepted: 09/19/2008] [Indexed: 11/20/2022]
Abstract
Decisions are often guided by generalizing from past experiences. Fundamental questions remain regarding the cognitive and neural mechanisms by which generalization takes place. Prior data suggest that generalization may stem from inference-based processes at the time of generalization. By contrast, generalization may emerge from mnemonic processes occurring while premise events are encoded. Here, participants engaged in a two-phase learning and generalization task, wherein they learned a series of overlapping associations and subsequently generalized what they learned to novel stimulus combinations. Functional MRI revealed that successful generalization was associated with coupled changes in learning-phase activity in the hippocampus and midbrain (ventral tegmental area/substantia nigra). These findings provide evidence for generalization based on integrative encoding, whereby overlapping past events are integrated into a linked mnemonic representation. Hippocampal-midbrain interactions support the dynamic integration of experiences, providing a powerful mechanism for building a rich associative history that extends beyond individual events.
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Affiliation(s)
- Daphna Shohamy
- Department of Psychology, Stanford University, Stanford, CA 94305-2130, USA.
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