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Almeida VN, Radanovic M. Semantic processing and neurobiology in Alzheimer's disease and Mild Cognitive Impairment. Neuropsychologia 2022; 174:108337. [DOI: 10.1016/j.neuropsychologia.2022.108337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2022] [Revised: 07/17/2022] [Accepted: 07/17/2022] [Indexed: 11/28/2022]
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Almeida VN. The neural hierarchy of consciousness. Neuropsychologia 2022; 169:108202. [PMID: 35271856 DOI: 10.1016/j.neuropsychologia.2022.108202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2021] [Revised: 02/25/2022] [Accepted: 03/01/2022] [Indexed: 01/08/2023]
Abstract
The chief undertaking in the studies of consciousness is that of unravelling "the minimal set of neural processes that are together sufficient for the conscious experience of a particular content - the neural correlates of consciousness". To this day, this crusade remains at an impasse, with a clash of two main theories: consciousness may arise either in a graded and cortically-localised fashion, or in an all-or-none and widespread one. In spite of the long-lasting theoretical debates, neurophysiological theories of consciousness have been mostly dissociated from them. Herein, a theoretical review will be put forth with the aim to change that. In its first half, we will cover the hard available evidence on the neurophysiology of consciousness, whereas in its second half we will weave a series of considerations on both theories and substantiate a novel take on conscious awareness: the levels of processing approach, partitioning the conscious architecture into lower- and higher-order, graded and nonlinear.
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Affiliation(s)
- Victor N Almeida
- Faculdade de Letras, Universidade Federal de Minas Gerais (UFMG), Av. Pres. Antônio Carlos, 6627, Pampulha, Belo Horizonte, MG, 31270-901, Brazil.
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Almeida VN, Radanovic M. Semantic priming and neurobiology in schizophrenia: A theoretical review. Neuropsychologia 2021; 163:108058. [PMID: 34655651 DOI: 10.1016/j.neuropsychologia.2021.108058] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Revised: 10/06/2021] [Accepted: 10/07/2021] [Indexed: 12/11/2022]
Abstract
In this theoretical review we bridge the cognitive and neurobiological sciences to shed light on the neurocognitive foundations of the semantic priming effect in schizophrenia. We review and theoretically evaluate the neurotransmitter systems (dopaminergic, GABAergic and glutamatergic) and neurobiological underpinnings of behavioural and electrophysiological (N400) semantic priming in the pathology, and the main hypotheses on their geneses: a disinhibition of the semantic spread of activation, a disorganised semantic storage or noisy lexical-semantic associations, a psychomotor artefact, an artefact of relatedness proportions, or an inability to mobilise contextual information. We further assess the literature on the endophenotype of Formal Thought Disorder from multiple standpoints, ranging from neurophysiology to cognition: considerations are weaved on neuronal (PV basket cell, SST, VIP) and receptor deficits (DRD1, NMDA), neurotransmitter imbalances (dopamine), cortical and dopaminergic lateralisation, inter alia. In conclusion, we put forth novel postulates on the underlying causes of controlled hypopriming, automatic hyperpriming, N400 reversals (larger amplitudes for close associations), indirect versus direct hyperpriming, and the endophenotype of lexical-semantic disturbances in schizophrenia.
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Affiliation(s)
- Victor N Almeida
- Faculdade de Letras, Universidade Federal de Minas Gerais (UFMG), Av. Pres. Antônio Carlos, 6627 - Pampulha, Belo Horizonte, MG, 31270-901, Brazil.
| | - Marcia Radanovic
- Laboratório de Neurociências (LIM-27), Faculdade de Medicina, Departamento e Instituto de Psiquiatria, Hospital das Clínicas HCFMUSP, Universidade de São Paulo, Brazil
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4
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Neurophysiological basis of the N400 deflection, from Mismatch Negativity to Semantic Prediction Potentials and late positive components. Int J Psychophysiol 2021; 166:134-150. [PMID: 34097935 DOI: 10.1016/j.ijpsycho.2021.06.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/20/2021] [Accepted: 06/02/2021] [Indexed: 11/21/2022]
Abstract
The first theoretical model on the neurophysiological basis of the N400: the deflection reflects layer I dendritic plateaus on a preparatory state of synaptic integration that precedes layer V somatic burst firing for conscious identification of the higher-order features of the stimulus (a late positive shift). Plateaus ensue from apical disinhibition by vasoactive intestinal polypeptide-positive interneurons (VIPs) through suppression of Martinotti cells, opening the gates for glutamatergic feedback to trigger dendritic regenerative potentials. Cholinergic transients contribute to these dynamics directly, holding a central role in the N400 deflection. The stereotypical timing of the (frontal) glutamatergic feedback and the accompanying cholinergic transients account for the enigmatic "invariability" of the peak latency in the face of a gamut of different stimuli and paradigms. The theoretical postulations presented here may bring about unprecedented level of detail for the N400 deflection to be used in the study of schizophrenia, Alzheimer's disease and other higher-order pathologies. The substrates of a late positive component, the Mismatch Negativity and the Semantic Prediction Potentials are also surveyed.
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Lepock JR, Ahmed S, Mizrahi R, Gerritsen CJ, Maheandiran M, Drvaric L, Bagby RM, Korostil M, Light GA, Kiang M. Relationships between cognitive event-related brain potential measures in patients at clinical high risk for psychosis. Schizophr Res 2020; 226:84-94. [PMID: 30683525 DOI: 10.1016/j.schres.2019.01.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/01/2018] [Revised: 01/11/2019] [Accepted: 01/14/2019] [Indexed: 12/14/2022]
Abstract
Neurophysiological measures of cognitive functioning that are abnormal in patients with schizophrenia are promising candidate biomarkers for predicting development of psychosis in individuals at clinical high risk (CHR). We examined the relationships among event-related brain potential (ERP) measures of early sensory, pre-attentional, and attention-dependent cognition, in antipsychotic-naïve help-seeking CHR patients (n = 36) and healthy control participants (n = 22). These measures included the gamma auditory steady-state response (ASSR; early sensory); mismatch negativity (MMN) and P3a (pre-attentional); and N400 semantic priming effects - a measure of using meaningful context to predict related items - over a shorter and a longer time interval (attention-dependent). Compared to controls, CHR patients had significantly smaller P3a amplitudes (d = 0.62, p = 0.03) and N400 priming effects over the long interval (d = 0.64, p = 0.02). In CHR patients, gamma ASSR evoked power and phase-locking factor were correlated (r = 0.41, p = 0.03). Reductions in mismatch negativity (MMN) and P3a amplitudes were also correlated (r = -0.36, p = 0.04). Moreover, lower gamma ASSR evoked power correlated with smaller MMN amplitudes (r = -0.45, p = 0.02). MMN amplitude reduction was also associated with reduced N400 semantic priming over the shorter but not the longer interval (r = 0.52, p < 0.002). This pattern of results suggests that, in a subset of CHR patients, impairment in pre-attentional measures of early information processing may contribute to deficits in attention-dependent cognition involving rapid, more automatic processing, but may be independent from pathological processes affecting more controlled or strategic processing. Thus, combining neurophysiological indices of cognitive deficits in different domains offers promise for improving their predictive power as prognostic biomarkers of clinical outcome.
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Affiliation(s)
- Jennifer R Lepock
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Sarah Ahmed
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - Romina Mizrahi
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Cory J Gerritsen
- Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Graduate Department of Psychological Clinical Science, University of Toronto, Toronto, Ontario, Canada
| | | | - Lauren Drvaric
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Centre for Addiction and Mental Health, Toronto, Ontario, Canada
| | - R Michael Bagby
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada; Graduate Department of Psychological Clinical Science, University of Toronto, Toronto, Ontario, Canada
| | - Michele Korostil
- Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada
| | - Gregory A Light
- Department of Psychiatry, University of California, San Diego, La Jolla, CA, United States
| | - Michael Kiang
- Institute of Medical Science, University of Toronto, Toronto, Ontario, Canada; Centre for Addiction and Mental Health, Toronto, Ontario, Canada; Department of Psychiatry, University of Toronto, Toronto, Ontario, Canada.
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Li W, Kutas M, Gray JA, Hagerman RH, Olichney JM. The Role of Glutamate in Language and Language Disorders - Evidence from ERP and Pharmacologic Studies. Neurosci Biobehav Rev 2020; 119:217-241. [PMID: 33039453 DOI: 10.1016/j.neubiorev.2020.09.023] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 08/10/2020] [Accepted: 09/21/2020] [Indexed: 12/31/2022]
Abstract
Current models of language processing do not address mechanisms at the neurotransmitter level, nor how pharmacologic agents may improve language function(s) in seemingly disparate disorders. L-Glutamate, the primary excitatory neurotransmitter in the human brain, is extensively involved in various higher cortical functions. We postulate that the physiologic role of L-Glutamate neurotransmission extends to the regulation of language access, comprehension, and production, and that disorders in glutamatergic transmission and circuitry contribute to the pathogenesis of neurodegenerative diseases and sporadic-onset language disorders such as the aphasic stroke syndromes. We start with a review of basic science data pertaining to various glutamate receptors in the CNS and ways that they may influence the physiological processes of language access and comprehension. We then focus on the dysregulation of glutamate neurotransmission in three conditions in which language dysfunction is prominent: Alzheimer's Disease, Fragile X-associated Tremor/Ataxia Syndrome, and Aphasic Stroke Syndromes. Finally, we review the pharmacologic and electrophysiologic (event related brain potential or ERP) data pertaining to the role glutamate neurotransmission plays in language processing and disorders.
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Affiliation(s)
- Wentao Li
- Department of Neurology, University of California, Davis, 4860 Y Street, Suite 3700, Sacramento, CA, 95817, USA.
| | - Marta Kutas
- Department of Cognitive Science, University of California, San Diego, 9500 Gilman Drive #0515, La Jolla, CA, 92093, USA; Department of Neurosciences, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA, 92093, USA.
| | - John A Gray
- Department of Neurology, University of California, Davis, 4860 Y Street, Suite 3700, Sacramento, CA, 95817, USA; Center for Neuroscience, University of California, Davis, 1544 Newton Court, Davis, CA, 95618, USA.
| | - Randi H Hagerman
- MIND Institute, University of California, Davis, 2825 50th Street, Sacramento, CA, 95817, USA.
| | - John M Olichney
- Department of Neurology, University of California, Davis, 4860 Y Street, Suite 3700, Sacramento, CA, 95817, USA; Center for Mind and Brain, University of California, Davis, 267 Cousteau Place, Davis, CA, 95618, USA.
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Derner M, Chaieb L, Surges R, Staresina BP, Fell J. Modulation of Item and Source Memory by Auditory Beat Stimulation: A Pilot Study With Intracranial EEG. Front Hum Neurosci 2018; 12:500. [PMID: 30618681 PMCID: PMC6297717 DOI: 10.3389/fnhum.2018.00500] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Accepted: 11/27/2018] [Indexed: 12/19/2022] Open
Abstract
Auditory beat stimulation is an upcoming technique for non-invasive brain stimulation. Its influence on mediotemporal regions and memory processes has not yet been thoroughly investigated. A recent study suggests that auditory beats are able to alter intracranial EEG (iEEG) power and phase synchronization. 5 Hz binaural beat stimulation increased temporo-lateral phase synchronization, while 5 Hz monaural beat stimulation decreased mediotemporal synchronization. Based on the relevance of phase synchronization for memory operations, we hypothesized that 5 Hz binaural beat stimulation enhances, while 5 Hz monaural beat stimulation decreases long-term memory performance. We analyzed data from presurgical epilepsy patients with implanted depth electrodes in the hippocampus and rhinal cortex. 5 Hz monaural and binaural beat vs. control stimulation was applied while patients performed an associative learning task involving item and source recognition. We evaluated behavioral effects for item (hits minus false alarms) and source memory (correct minus incorrect) and the impact of auditory beats on iEEG power, rhinal-hippocampal phase synchronization and inter-trial phase locking. A three-way repeated measures ANOVA (encoding/retrieval, item/source, monaural/binaural/control) revealed a main effect of stimulation (p = 0.03) and a linear effect in the expected direction: binaural > control > monaural (p = 0.036). Both monaural and binaural stimulation were associated with increased phase locking of 5 Hz oscillations within rhinal cortex. These phase locking increases, however, corresponded to reverse phase shifts. Our data suggest that binaural vs. monaural 5 Hz stimulation increases vs. decreases long-term memory performance. These behavioral effects appear to be related to reverse phase shifts within rhinal cortex.
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Affiliation(s)
- Marlene Derner
- Department of Epileptology, University of Bonn, Bonn, Germany
| | - Leila Chaieb
- Department of Epileptology, University of Bonn, Bonn, Germany
| | - Rainer Surges
- Department of Epileptology, University of Bonn, Bonn, Germany.,Department of Neurology, University Hospital RWTH Aachen, Aachen, Germany
| | | | - Juergen Fell
- Department of Epileptology, University of Bonn, Bonn, Germany
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Iacobas DA, Iacobas S, Nebieridze N, Velíšek L, Velíšková J. Estrogen Protects Neurotransmission Transcriptome During Status Epilepticus. Front Neurosci 2018; 12:332. [PMID: 29973860 PMCID: PMC6019481 DOI: 10.3389/fnins.2018.00332] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 04/30/2018] [Indexed: 01/27/2023] Open
Abstract
Women with epilepsy commonly have premature onset of menopause. The decrease in estrogen levels is associated with increased occurrence of neurodegenerative processes and cognitive decline. Previously, we found that estradiol (E2) replacement in ovariectomized (OVX) female rats significantly reduced the seizure-related damage in the sensitive hilar region of hippocampal dentate gyrus (DG). However, the complex mechanisms by which E2 empowers the genomic fabrics of neurotransmission to resist damaging effects of status epilepticus (SE) are still unclear. We determined the protective effects of the estradiol replacement against kainic acid-induced SE-associated transcriptomic alterations in the DG of OVX rats. Without E2 replacement, SE altered expression of 44% of the DG genes. SE affected all major functional pathways, including apoptosis (61%), Alzheimer's disease (47%), cell cycle (59%), long-term potentiation (62%), and depression (55%), as well as synaptic vesicle cycle (62%), glutamatergic (53%), GABAergic (49%), cholinergic (52%), dopaminergic (55%), and serotonergic (49%) neurotransmission. However, in rats with E2 replacement the percentage of significantly affected genes after SE was reduced to the average 11% (from 8% for apoptosis to 32% for GABAergic synapse). Interestingly, while SE down-regulated most of the synaptic receptor genes in oil-injected females it had little effect on these receptors after E2-replacement. Our novel Pathway Protection analysis indicated that the E2-replacement prevented SE-related damage from 50% for GABA to 75% for dopaminergic transmission. The 15% synergistic expression between genes involved in estrogen signaling (ESG) and neurotransmission explains why low E2 levels result in down-regulation of neurotransmission. Interestingly, in animals with E2-replacement, SE switched 131 synergistically expressed ESG-neurotransmission gene pairs into antagonistically expressed gene pairs. Thus, the ESG pathway acts like a buffer against SE-induced alteration of neurotransmission that may contribute to the E2-mediated maintenance of brain function after the SE injury in postmenopausal women. We also show that the long-term potentiation is lost in OVX rats following SE but not in those with E2 replacement. The electrophysiological findings in OVX female rats with SE are corroborated by the high percentage of long-term potentiation regulated genes (62%) in oil-injected while only 13% of genes were regulated following SE in E2-replaced rats.
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Affiliation(s)
- Dumitru A Iacobas
- Center for Computational Systems Biology, Prairie View A&M University, Prairie View, TX, United States.,DP Purpura Department of Neuroscience, Albert Einstein College of Medicine, New York, NY, United States
| | - Sanda Iacobas
- Center for Computational Systems Biology, Prairie View A&M University, Prairie View, TX, United States.,Department of Pathology, New York Medical College, Valhalla, NY, United States
| | - Nino Nebieridze
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, United States
| | - Libor Velíšek
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, United States.,Department of Pediatrics, New York Medical College, Valhalla, NY, United States.,Department of Neurology, New York Medical College, Valhalla, NY, United States
| | - Jana Velíšková
- Department of Cell Biology & Anatomy, New York Medical College, Valhalla, NY, United States.,Department of Neurology, New York Medical College, Valhalla, NY, United States.,Department of Obstetrics & Gynecology, New York Medical College, Valhalla, NY, United States
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Gao H, Zhang L, Chen Z, Liu S, Zhang Q, Zhang B. Effects of intravenous anesthetics on the phosphorylation of cAMP response element‑binding protein in hippocampal slices of adult mice. Mol Med Rep 2018; 18:627-633. [PMID: 29749444 DOI: 10.3892/mmr.2018.8939] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Accepted: 04/17/2018] [Indexed: 11/06/2022] Open
Abstract
cAMP response‑element binding protein (CREB) functions in hippocampal synaptic plasticity and memory formation. However, it remains unknown whether intravenous anesthetics modulate CREB. The present study aimed to examine the effects of intravenous anesthetics on CREB phosphorylation in the mouse hippocampus. CREB phosphorylation was examined in hippocampal slices with and without pharmacological or intravenous anesthetics via immunoblotting. In a dose‑response experiment, the concentrations of intravenous anesthetics ranged from 10‑9 to 10‑4 mol/l for 1 h. For the time‑response experiment, these slices were incubated with 5x10‑6 mol/l of propofol for 0, 1, 2, 5, 7, 9, 12, 15, 30 and 60 min. In order to examine whether CREB phosphorylation could be recovered following washing out the propofol, the slices were incubated in plain artificial cerebrospinal fluid at different time durations following 5 min incubation with propofol. Propofol, etomidate, ketamine and midazolam inhibited CREB phosphorylation (P<0.05) in a time‑ and dose‑dependent manner. This inhibition was reversible following the removal of propofol, and was rescued by CREB phosphorylation (P<0.05). The decrease in CREB phosphorylation revealed additive effects with 100 µM of chelerythrine and 20 µM of PD‑98059, and the etomidate‑induced decrease in CREB phosphorylation was blocked by 1 mM of NMDA. However, 0.1 µM of phorbol 12‑myristate 13‑acetate, 50 µM of U 73122, 100 µM of carbachol and 10 µM of MK801 were ineffective in the anesthetic‑induced decrease in CREB phosphorylation. Intravenous anesthetics markedly decreased CREB phosphorylation in the mouse hippocampus, which was most likely via the protein kinase C and mitogen activated protein kinase pathways. This suggests that CREB represents a target for anesthetic action in the brain.
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Affiliation(s)
- Haiying Gao
- Department of Anesthesiology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian 361003, P.R. China
| | - Lingyu Zhang
- Department of Anesthesiology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian 361003, P.R. China
| | - Zhenyi Chen
- Department of Anesthesiology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian 361003, P.R. China
| | - Shuncui Liu
- Department of Anesthesiology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian 361003, P.R. China
| | - Qinghong Zhang
- Department of Anesthesiology, The First Affiliated Hospital of Xiamen University, Xiamen, Fujian 361003, P.R. China
| | - Bingxi Zhang
- Department of Anesthesiology, Affiliated Beijing Tongren Hospital, Capital University of Medical Science, Beijing 100000, P.R. China
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Höhne M, Jahanbekam A, Bauckhage C, Axmacher N, Fell J. Prediction of successful memory encoding based on single-trial rhinal and hippocampal phase information. Neuroimage 2016; 139:127-135. [PMID: 27311642 DOI: 10.1016/j.neuroimage.2016.06.021] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Revised: 05/09/2016] [Accepted: 06/12/2016] [Indexed: 11/16/2022] Open
Abstract
Mediotemporal EEG characteristics are closely related to long-term memory formation. It has been reported that rhinal and hippocampal EEG measures reflecting the stability of phases across trials are better suited to distinguish subsequently remembered from forgotten trials than event-related potentials or amplitude-based measures. Theoretical models suggest that the phase of EEG oscillations reflects neural excitability and influences cellular plasticity. However, while previous studies have shown that the stability of phase values across trials is indeed a relevant predictor of subsequent memory performance, the effect of absolute single-trial phase values has been little explored. Here, we reanalyzed intracranial EEG recordings from the mediotemporal lobe of 27 epilepsy patients performing a continuous word recognition paradigm. Two-class classification using a support vector machine was performed to predict subsequently remembered vs. forgotten trials based on individually selected frequencies and time points. We demonstrate that it is possible to successfully predict single-trial memory formation in the majority of patients (23 out of 27) based on only three single-trial phase values given by a rhinal phase, a hippocampal phase, and a rhinal-hippocampal phase difference. Overall classification accuracy across all subjects was 69.2% choosing frequencies from the range between 0.5 and 50Hz and time points from the interval between -0.5s and 2s. For 19 patients, above chance prediction of subsequent memory was possible even when choosing only time points from the prestimulus interval (overall accuracy: 65.2%). Furthermore, prediction accuracies based on single-trial phase surpassed those based on single-trial power. Our results confirm the functional relevance of mediotemporal EEG phase for long-term memory operations and suggest that phase information may be utilized for memory enhancement applications based on deep brain stimulation.
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Affiliation(s)
- Marlene Höhne
- Department of Epileptology, University of Bonn, D-53105 Bonn, Germany
| | | | - Christian Bauckhage
- Bonn-Aachen International Center for Information Technology, University of Bonn, D-53113 Bonn, Germany; Fraunhofer Institute for Intelligent Analysis and Information Systems IAIS, D-53757 Sankt Augustin, Germany
| | - Nikolai Axmacher
- Department of Neuropsychology, Institute of Cognitive Neuroscience, Faculty of Psychology, Ruhr University Bochum, D-44801 Bochum, Germany; German Center for Neurodegenerative Diseases (DZNE), D-53175 Bonn, Germany
| | - Juergen Fell
- Department of Epileptology, University of Bonn, D-53105 Bonn, Germany.
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11
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Hartzell JF, Davis B, Melcher D, Miceli G, Jovicich J, Nath T, Singh NC, Hasson U. Brains of verbal memory specialists show anatomical differences in language, memory and visual systems. Neuroimage 2015; 131:181-92. [PMID: 26188261 DOI: 10.1016/j.neuroimage.2015.07.027] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2014] [Revised: 06/19/2015] [Accepted: 07/08/2015] [Indexed: 12/14/2022] Open
Abstract
We studied a group of verbal memory specialists to determine whether intensive oral text memory is associated with structural features of hippocampal and lateral-temporal regions implicated in language processing. Professional Vedic Sanskrit Pandits in India train from childhood for around 10years in an ancient, formalized tradition of oral Sanskrit text memorization and recitation, mastering the exact pronunciation and invariant content of multiple 40,000-100,000 word oral texts. We conducted structural analysis of gray matter density, cortical thickness, local gyrification, and white matter structure, relative to matched controls. We found massive gray matter density and cortical thickness increases in Pandit brains in language, memory and visual systems, including i) bilateral lateral temporal cortices and ii) the anterior cingulate cortex and the hippocampus, regions associated with long and short-term memory. Differences in hippocampal morphometry matched those previously documented for expert spatial navigators and individuals with good verbal working memory. The findings provide unique insight into the brain organization implementing formalized oral knowledge systems.
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Affiliation(s)
- James F Hartzell
- Center for Mind/Brain Sciences (CIMeC), University of Trento, 38060, Italy.
| | - Ben Davis
- Center for Mind/Brain Sciences (CIMeC), University of Trento, 38060, Italy
| | - David Melcher
- Center for Mind/Brain Sciences (CIMeC), University of Trento, 38060, Italy
| | - Gabriele Miceli
- Center for Mind/Brain Sciences (CIMeC), University of Trento, 38060, Italy
| | - Jorge Jovicich
- Center for Mind/Brain Sciences (CIMeC), University of Trento, 38060, Italy
| | - Tanmay Nath
- National Brain Research Centre, Manesar, Gurgaon Dist., Haryana 122 050, India
| | | | - Uri Hasson
- Center for Mind/Brain Sciences (CIMeC), University of Trento, 38060, Italy
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12
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Characterising neural signatures of successful aging: Electrophysiological correlates of preserved episodic memory in older age. Brain Cogn 2015; 97:40-50. [DOI: 10.1016/j.bandc.2015.04.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 04/03/2015] [Accepted: 04/07/2015] [Indexed: 11/23/2022]
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13
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The 9th International Symposium on Memory and Awareness in Anesthesia (MAA9). Br J Anaesth 2015. [DOI: 10.1093/bja/aev204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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14
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Lamb YN, McKay NS, Thompson CS, Hamm JP, Waldie KE, Kirk IJ. Brain-derived neurotrophic factor Val66Met polymorphism, human memory, and synaptic neuroplasticity. WILEY INTERDISCIPLINARY REVIEWS. COGNITIVE SCIENCE 2014; 6:97-108. [PMID: 26263066 DOI: 10.1002/wcs.1334] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2013] [Revised: 10/20/2014] [Accepted: 11/07/2014] [Indexed: 11/09/2022]
Abstract
Some people have much better memory than others, and there is compelling evidence that a considerable proportion of this variation in memory ability is genetically inherited. A form of synaptic plasticity known as long-term potentiation (LTP) is the principal candidate mechanism underlying memory formation in neural circuits, and it might be expected, therefore, that a genetic influence on the degree of LTP might in turn influence memory abilities. Of the genetic variations thought to significantly influence mnemonic ability in humans, the most likely to have its effect via LTP is a single nucleotide polymorphism affecting brain-derived neurotrophic factor [BDNF (Val66Met)]. However, although it is likely that BDNF influences memory via a modulation of acute plasticity (i.e., LTP), BDNF also has considerable influence on structural development of neural systems. Thus, the influence of BDNF (Val66Met) on mnemonic performance via influences of brain structure as well as function must also be considered. In this brief review, we will describe the phenomenon of LTP and its study in non-human animals. We will discuss the relatively recent attempts to translate this work to studies in humans. We will describe how this has enabled investigation of the effect of the BDNF polymorphism on LTP, on brain structure, and on memory performance.
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Affiliation(s)
- Yvette N Lamb
- School of Psychology, University of Auckland, Auckland, New Zealand
| | - Nicole S McKay
- School of Psychology, University of Auckland, Auckland, New Zealand
| | | | - Jeffrey P Hamm
- School of Psychology, University of Auckland, Auckland, New Zealand
| | - Karen E Waldie
- School of Psychology, University of Auckland, Auckland, New Zealand
| | - Ian J Kirk
- School of Psychology, University of Auckland, Auckland, New Zealand
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Memantine effects on verbal memory in fragile X-associated tremor/ataxia syndrome (FXTAS): a double-blind brain potential study. Neuropsychopharmacology 2014; 39:2760-8. [PMID: 24871547 PMCID: PMC4200486 DOI: 10.1038/npp.2014.122] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 04/29/2014] [Accepted: 05/08/2014] [Indexed: 12/19/2022]
Abstract
Older FMR1 premutation carriers may develop fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disorder manifesting cognitive deficits that often subsequently progress to dementia. To date, there is no specific treatment available for FXTAS. Studies have demonstrated the premutation-associated overactivation of glutamatergic receptors in neurons. Memantine, a NMDA receptor antagonist approved for treatment of Alzheimer's disease, thus was tested in the first placebo-controlled, double-blind, randomized clinical trial in FXTAS. Prior event-related brain potential (ERP) studies in FXTAS found reduced N400 repetition effect, a glutamate-related electrophysiological marker of semantic priming, and verbal memory processes. This substudy of the randomized clinical trial of memantine in FXTAS sought to use the N400 repetition effect to evaluate effects of chronic memantine treatment on verbal memory. Subsequent recall and recognition memory tests for the experimental stimuli were administered to characterize verbal memory. Data from 41 patients who completed the 1-year memantine trial (21 on memantine) and also completed longitudinal ERP studies were analyzed. Results showed treatment-associated benefits on both cued-recall memory and N400 repetition effect amplitude. Importantly, improvement in cued recall was positively correlated with amplitude increase of the N400 repetition effect. The placebo group, in contrast, displayed a significant reduction of the N400 repetition effect after 1 year. These results suggest that memantine treatment may have beneficial effects on verbal memory in FXTAS. Additional studies of memantine, perhaps in combination with other therapeutic agents, appear warranted, as symptomatic treatments and neuroprotective treatments are both needed for this recently recognized neurodegenerative disorder.
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16
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Yang JC, Chi L, Teichholtz S, Schneider A, Nanakul R, Nowacki R, Seritan A, Reed B, DeCarli C, Iragui VJ, Kutas M, Hagerman PJ, Hagerman RJ, Olichney JM. ERP abnormalities elicited by word repetition in fragile X-associated tremor/ataxia syndrome (FXTAS) and amnestic MCI. Neuropsychologia 2014; 63:34-42. [PMID: 25111034 DOI: 10.1016/j.neuropsychologia.2014.08.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2014] [Revised: 07/31/2014] [Accepted: 08/01/2014] [Indexed: 01/26/2023]
Abstract
BACKGROUND Fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disorder caused by FMR1 gene premutations, typically associated with frontal-subcortical type cognitive impairments. High prevalence (~50%) of superimposed Alzheimer׳s pathology has been reported in FMR1 premutation carriers, and standardized neuropsychological tests have not yielded any robust discriminators between FXTAS and Alzheimer׳s disease (AD) dementia. The similarities/differences in memory processes between FXTAS and early AD remain underexplored. METHODS 32-channel event-related potentials (ERPs) were obtained from a semantic judgment task in which semantically congruous (50%) and incongruous pairs repeat pseudorandomly. The N400 and late positive component (LPC) of 25 FXTAS patients (M(age)=71.2, MMSE=26.6) were compared to a matched group of 25 patients with MCI or early AD (1 mild AD dementia, 24 amnestic MCI, of whom 18 later converted to AD; M(age)=73.4, MMSE=26.4), and 25 healthy elderly. RESULTS Both patient groups showed similar reductions in the N400 repetition effect and N400 congruity effect amplitudes, compared to controls, reflecting abnormal semantic priming and repetition priming. The MCI/AD group, however, had significantly smaller LPC word repetition effects and poorer learning and memory on the CVLT than FXTAS. The LPC and N400 repetition effects both correlated with verbal memory across all subjects, but only N400 correlated with memory in FXTAS. CONCLUSION FXTAS patients show relative sparing of the LPC repetition effect, and less disruption of explicit memory than prodromal/early AD. N400 abnormalities in FXTAS appear to account for much of their mild impairments in verbal learning and memory.
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Affiliation(s)
- Jin-Chen Yang
- University of California Davis, Center for Mind and Brain, Davis, CA 95618-5412, USA; University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA.
| | - Lillian Chi
- University of California Davis, Center for Mind and Brain, Davis, CA 95618-5412, USA; University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA
| | - Sara Teichholtz
- University of California Davis, Center for Mind and Brain, Davis, CA 95618-5412, USA; University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA
| | - Andrea Schneider
- University of California Davis, M.I.N.D. Institute, School of Medicine, Sacramento, CA, USA; University of California Davis, Department of Pediatrics, School of Medicine, Sacramento, CA, USA
| | - Rawi Nanakul
- University of California Davis, Center for Mind and Brain, Davis, CA 95618-5412, USA; University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA
| | - Ralph Nowacki
- University of California San Diego, Department of Neurosciences, San Diego, CA, USA; VA San Diego Healthcare System, San Diego, CA, USA
| | - Andreea Seritan
- University of California Davis, Department of Psychiatry and Behavioral Sciences, School of Medicine, Sacramento, CA, USA
| | - Bruce Reed
- University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA
| | - Charles DeCarli
- University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA
| | - Vicente J Iragui
- University of California San Diego, Department of Neurosciences, San Diego, CA, USA; VA San Diego Healthcare System, San Diego, CA, USA
| | - Marta Kutas
- University of California San Diego, Department of Cognitive Sciences, San Diego, CA, USA
| | - Paul J Hagerman
- University of California Davis, Department of Biochemistry and Molecular Medicine, Davis, CA, USA
| | - Randi J Hagerman
- University of California Davis, M.I.N.D. Institute, School of Medicine, Sacramento, CA, USA; University of California Davis, Department of Pediatrics, School of Medicine, Sacramento, CA, USA
| | - John M Olichney
- University of California Davis, Center for Mind and Brain, Davis, CA 95618-5412, USA; University of California Davis, Department of Neurology, School of Medicine, Sacramento, CA 95618-5412, USA.
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Grigsby J, Cornish K, Hocking D, Kraan C, Olichney JM, Rivera SM, Schneider A, Sherman S, Wang JY, Yang JC. The cognitive neuropsychological phenotype of carriers of the FMR1 premutation. J Neurodev Disord 2014; 6:28. [PMID: 25136377 PMCID: PMC4135346 DOI: 10.1186/1866-1955-6-28] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Accepted: 01/27/2014] [Indexed: 11/10/2022] Open
Abstract
The fragile X-associated tremor/ataxia syndrome (FXTAS) is a late-onset neurodegenerative disorder affecting a subset of carriers of the FMR1 (fragile X mental retardation 1) premutation. Penetrance and expression appear to be significantly higher in males than females. Although the most obvious aspect of the phenotype is the movement disorder that gives FXTAS its name, the disorder is also accompanied by progressive cognitive impairment. In this review, we address the cognitive neuropsychological and neurophysiological phenotype for males and females with FXTAS, and for male and female unaffected carriers. Despite differences in penetrance and expression, the cognitive features of the disorder appear similar for both genders, with impairment of executive functioning, working memory, and information processing the most prominent. Deficits in these functional systems may be largely responsible for impairment on other measures, including tests of general intelligence and declarative learning. FXTAS is to a large extent a white matter disease, and the cognitive phenotypes observed are consistent with what some have described as white matter dementia, in contrast to the impaired cortical functioning more characteristic of Alzheimer's disease and related disorders. Although some degree of impaired executive functioning appears to be ubiquitous among persons with FXTAS, the data suggest that only a subset of unaffected carriers of the premutation - both female and male - demonstrate such deficits, which typically are mild. The best-studied phenotype is that of males with FXTAS. The manifestations of cognitive impairment among asymptomatic male carriers, and among women with and without FXTAS, are less well understood, but have come under increased scrutiny.
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Affiliation(s)
- Jim Grigsby
- Department of Psychology, University of Colorado Denver, Denver, CO, USA ; Department of Medicine; Division of Health Care Policy and Research, University of Colorado School of Medicine, Aurora, CO, USA
| | - Kim Cornish
- School of Psychology & Psychiatry; Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - Darren Hocking
- Olga Tennison Autism Research Centre, School of Psychological Science, La Trobe University, Melbourne, Victoria, Australia
| | - Claudine Kraan
- School of Psychology & Psychiatry; Faculty of Medicine, Nursing and Health Sciences, Monash University, Melbourne, Victoria, Australia
| | - John M Olichney
- Center for Mind and Brain, University of California, Davis, CA, USA ; Department of Neurology, University of California, Davis, Sacramento, CA, USA
| | - Susan M Rivera
- Center for Mind and Brain, University of California, Davis, CA, USA ; Department of Psychology, University of California-Davis, Sacramento, CA, USA ; MIND Institute, University of California-Davis Medical Center, Sacramento, CA, USA
| | - Andrea Schneider
- Center for Mind and Brain, University of California, Davis, CA, USA ; MIND Institute, University of California-Davis Medical Center, Sacramento, CA, USA
| | | | - Jun Yi Wang
- Center for Mind and Brain, University of California, Davis, CA, USA ; Department of Pediatrics, University of California, Davis, Sacramento, CA, USA
| | - Jin-Chen Yang
- Center for Mind and Brain, University of California, Davis, CA, USA ; Department of Neurology, University of California, Davis, Sacramento, CA, USA
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Scudder MR, Federmeier KD, Raine LB, Direito A, Boyd JK, Hillman CH. The association between aerobic fitness and language processing in children: implications for academic achievement. Brain Cogn 2014; 87:140-52. [PMID: 24747513 PMCID: PMC4036460 DOI: 10.1016/j.bandc.2014.03.016] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 03/21/2014] [Accepted: 03/24/2014] [Indexed: 11/25/2022]
Abstract
Event-related brain potentials (ERPs) have been instrumental for discerning the relationship between children's aerobic fitness and aspects of cognition, yet language processing remains unexplored. ERPs linked to the processing of semantic information (the N400) and the analysis of language structure (the P600) were recorded from higher and lower aerobically fit children as they read normal sentences and those containing semantic or syntactic violations. Results revealed that higher fit children exhibited greater N400 amplitude and shorter latency across all sentence types, and a larger P600 effect for syntactic violations. Such findings suggest that higher fitness may be associated with a richer network of words and their meanings, and a greater ability to detect and/or repair syntactic errors. The current findings extend previous ERP research explicating the cognitive benefits associated with greater aerobic fitness in children and may have important implications for learning and academic performance.
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Affiliation(s)
- Mark R Scudder
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | | | - Lauren B Raine
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Artur Direito
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
| | - Jeremy K Boyd
- University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.
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Liu H, Xu GH, Wang K, Cao JL, Gu EW, Li YH, Liu XS. Involvement of GSK3β/β-catenin signaling in the impairment effect of ketamine on spatial memory consolidation in rats. Neurobiol Learn Mem 2014; 111:26-34. [DOI: 10.1016/j.nlm.2014.02.012] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2013] [Revised: 02/19/2014] [Accepted: 02/22/2014] [Indexed: 01/09/2023]
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20
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Yang JC, Simon C, Schneider A, Seritan AL, Hamilton L, Hagerman PJ, Hagerman RJ, Olichney JM. Abnormal semantic processing in females with fragile X-associated tremor/ataxia syndrome. GENES BRAIN AND BEHAVIOR 2013; 13:152-62. [PMID: 24299169 DOI: 10.1111/gbb.12114] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Revised: 11/12/2013] [Accepted: 11/28/2013] [Indexed: 11/29/2022]
Abstract
Fragile X-associated tremor/ataxia syndrome (FXTAS), a neurodegenerative disorder, affects fragile X (FMR1) gene premutation carriers in late life. Studies have shown cognitive impairments in FXTAS including executive dysfunction, working memory and visuospatial deficits. However, less is known about cognition in females with FXTAS. Thus, we examined semantic processing and verbal memory in female FXTAS patients with event-related potentials (ERPs) and neuropsychological testing. Sixty-one females (34 FXTAS, Mage = 62.7; 27 controls, Mage = 60.4) were studied with 32-channel ERPs during a category judgment task in which semantically congruous (50%) and incongruous items were repeated approximately 10-140 seconds later. N400 and P600 amplitude data were submitted to analysis of covariance. Neuropsychological testing demonstrated lower performance in verbal learning and executive function in females with FXTAS. Event-related potential analyses showed a significant reduction of the N400 congruity effect (incongruous - congruous) in the FXTAS group. The N400 congruity effect reduction in females with FXTAS was mainly due to increased N400 amplitude to congruous new words. No significant abnormalities of the N400 repetition effect or the P600 repetition effect were found, indicating preserved implicit memory and verbal memory, respectively, in females with FXTAS. The decreased N400 congruity effect suggests abnormal semantic expectancy and/or semantic network disorganization in female FXTAS patients. The enhanced N400 amplitude to congruous new words may reflect decreased cognitive flexibility among FXTAS women, making access to less typical category exemplar words more difficult.
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Affiliation(s)
- J-C Yang
- Department of Neurology, University of California Davis School of Medicine, Sacramento; Center for Mind and Brain, University of California Davis, Davis
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21
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Olichney JM, Pak J, Salmon DP, Yang JC, Gahagan T, Nowacki R, Hansen L, Galasko D, Kutas M, Iragui-Madoz VJ. Abnormal P600 word repetition effect in elderly persons with preclinical Alzheimer's disease. Cogn Neurosci 2013; 4:143-51. [PMID: 24090465 DOI: 10.1080/17588928.2013.838945] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
We sought cognitive event-related potential (ERP) biomarkers of "Preclinical Alzheimer's disease" (Pre-AD) using an incidental verbal learning paradigm with high sensitivity to prodromal AD. Seven elderly persons, with normal cognition at the time of ERP recordings, but who showed subsequent cognitive decline or AD pathology at autopsy (n = 5, mean Braak stage = 2.8), were compared to 12 "robust" normal elderly (RNE) persons who remained cognitively normal (Mfollow-up = 9.0 years). EEG was recorded during a word repetition paradigm (semantically congruous (50%) and incongruous target words repeat ~10-140 seconds later). The RNE P600 congruous word repetition ERP effects (New minus Old congruous words) were significantly larger than in Pre-AD (mean amplitudes = 3.28 vs. 0.10 μV, p = .04). High group discrimination (84%) was achieved (by a P600 amplitude cutoff of ~1.5 μV). Abnormal P600 word repetition effects in cognitively normal elderly persons may be an important sign of synaptic dysfunction and Preclinical AD.
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Affiliation(s)
- John M Olichney
- a Department of Neurology , University of California , Davis , CA , USA
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22
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Hoffman KL, Basurto E. One-trial object recognition memory in the domestic rabbit (Oryctolagus cuniculus) is disrupted by NMDA receptor antagonists. Behav Brain Res 2013; 250:62-73. [PMID: 23651879 DOI: 10.1016/j.bbr.2013.04.049] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2012] [Revised: 04/24/2013] [Accepted: 04/28/2013] [Indexed: 11/28/2022]
Abstract
The spontaneous response to novelty is the basis of one-trial object recognition tests for the study of object recognition memory (ORM) in rodents. We describe an object recognition task for the rabbit, based on its natural tendency to scent-mark ("chin") novel objects. The object recognition task comprised a 15min sample phase in which the rabbit was placed into an open field arena containing two similar objects, then removed for a 5-360min delay, and then returned to the same arena that contained one object similar to the original ones ("Familiar") and one that differed from the original ones ("Novel"), for a 15min test phase. Chin-marks directed at each of the objects were registered. Some animals received injections (sc) of saline, ketamine (1mg/kg), or MK-801 (37μg/kg), 5 or 20min before the sample phase. We found that chinning decreased across the sample phase, and that this response showed stimulus specificity, a defining characteristic of habituation: in the test phase, chinning directed at the Novel, but not Familiar, object was increased. Chinning directed preferentially at the novel object, which we interpret as novelty-induced sensitization and the behavioral correlate of ORM, was promoted by tactile/visual and spatial novelty. ORM deficits were induced by pre-treatment with MK-801 and, to a lesser extent, ketamine. Novel object discrimination was not observed after delays longer than 5min. These results suggest that short-term habituation and sensitization, not long-term memory, underlie novel object discrimination in this test paradigm.
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Affiliation(s)
- Kurt Leroy Hoffman
- Centro de Investigación en Reproducción Animal (CIRA), Universidad Autónoma de Tlaxcala-CINVESTAV, Tlaxcala, Mexico.
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23
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Morris RGM. NMDA receptors and memory encoding. Neuropharmacology 2013; 74:32-40. [PMID: 23628345 DOI: 10.1016/j.neuropharm.2013.04.014] [Citation(s) in RCA: 207] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 04/04/2013] [Accepted: 04/09/2013] [Indexed: 12/15/2022]
Abstract
It is humbling to think that 30 years have passed since the paper by Collingridge, Kehl and McLennan showing that one of Jeff Watkins most interesting compounds, R-2-amino-5-phosphonopentanoate (d-AP5), blocked the induction of long-term potentiation in vitro at synapses from area CA3 of the hippocampus to CA1 without apparent effect on baseline synaptic transmission (Collingridge et al., 1983). This dissociation was one of the key triggers for an explosion of interest in glutamate receptors, and much has been discovered since that collectively contributes to our contemporary understanding of glutamatergic synapses - their biophysics and subunit composition, of the agonists and antagonists acting on them, and their diverse functions in different networks of the brain and spinal cord. It can be fairly said that Collingridge et al.'s (1983) observation was the stimulus that has led, on the one hand, to structural biological work at the atomic scale describing the key features of NMDA receptors that enables their coincidence function to happen; and, on the other, to work with whole animals investigating the contributions that calcium signalling via this receptor can have on rhythmical activities controlled by spinal circuits, memory encoding in the hippocampus (the topic of this article), visual cortical plasticity, sensitization in pain, and other functions. In this article, I lay out how my then interest in long-term potentiation (LTP) as a model of memory enabled me to recognise the importance of Collingridge et al.'s discovery - and how I and my colleagues endeavoured to take things forward in the area of learning and memory. This is in some respects a personal story, and I tell it as such. The idea that NMDA receptor activation is essential for memory encoding, though not for storage, took time to develop and to be accepted. Along the way, there have been confusions, challenges, and surprises surrounding the idea that activation of NMDA receptors can trigger memory. Some of these are described and how they have been addressed and resolved. Last, I touch on some new directions of interest with respect to the functional role of the NMDA receptor in cognition. This article is part of the Special Issue entitled 'Glutamate Receptor-Dependent Synaptic Plasticity'.
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Affiliation(s)
- Richard G M Morris
- Centre for Cognitive and Neural Systems, Edinburgh Neuroscience, The University of Edinburgh, 1 George Square, Edinburgh EH8 9JZ, UK.
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Klement J, Pais I, Strube J, Lehnert H, Peters A, Hallschmid M, Born J. NMDA receptor blockade by memantine does not prevent adaptation to recurrent hypoglycaemia in healthy men. Diabetes Obes Metab 2013; 15:310-5. [PMID: 23072263 DOI: 10.1111/dom.12027] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2012] [Revised: 08/27/2012] [Accepted: 10/09/2012] [Indexed: 11/28/2022]
Abstract
AIMS Recurrent hypoglycaemia leads to an attenuation of hypoglycaemic symptoms and hormonal counterregulatory responses. This phenomenon poses a severe problem in the treatment of patients with diabetes mellitus, but the underlying neuroendocrine mechanisms are unclear. On the basis of animal experimental findings, we hypothesized that counterregulatory attenuation represents a basic adaptive learning process relying on synaptic long-term potentiation or depression. If so, attenuation should be prevented by blocking glutamatergic N-methyl-D-aspartate (NMDA) receptors. METHODS Sixteen healthy young men participated in two conditions, separated by 4 weeks. Participants received the NMDA antagonist memantine over 5 days (15 mg/day) in one condition and placebo in the other one. After 3 days of drug administration, participants underwent two hypoglycaemic clamps on day 4 and another one on day 5. We assessed blood concentrations of counterregulatory hormones (cortisol, ACTH, epinephrine, norepinephrine, growth hormone and glucagon) as well as subjective symptoms of hypoglycaemia and word-list recall as an indicator of short-term memory. RESULTS Counterregulatory responses of all hormones as well as neuroglycopenic and autonomic symptom ratings showed robust attenuation following the third as compared to the first hypoglycaemia (p < 0.05). NMDA receptor antagonization by memantine impaired memory function but did not alter any neuroendocrine measure of counterregulatory attenuation (p > 0.17). CONCLUSIONS Attenuation of the endocrine as well as symptomatic counterregulatory response to recurrent hypoglycaemia is not prevented by the NMDA receptor blocker memantine. Our results do not support the view that adaptation to repeated hypoglycaemia relies on NMDA receptor-mediated plastic processes involving long-term potentiation or depression.
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Affiliation(s)
- J Klement
- Department of Internal Medicine I, University of Lübeck, Lübeck, Germany.
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Developmental regulation of expression of schizophrenia susceptibility genes in the primate hippocampal formation. Transl Psychiatry 2012; 2:e173. [PMID: 23092977 PMCID: PMC3565813 DOI: 10.1038/tp.2012.105] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
The hippocampal formation is essential for normal memory function and is implicated in many neurodevelopmental, neurodegenerative and neuropsychiatric disorders. In particular, abnormalities in hippocampal structure and function have been identified in schizophrenic subjects. Schizophrenia has a strong polygenic component, but the role of numerous susceptibility genes in normal brain development and function has yet to be investigated. Here we described the expression of schizophrenia susceptibility genes in distinct regions of the monkey hippocampal formation during early postnatal development. We found that, as compared with other genes, schizophrenia susceptibility genes exhibit a differential regulation of expression in the dentate gyrus, CA3 and CA1, over the course of postnatal development. A number of these genes involved in synaptic transmission and dendritic morphology exhibit a developmental decrease of expression in CA3. Abnormal CA3 synaptic organization observed in schizophrenics might be related to some specific symptoms, such as loosening of association. Interestingly, changes in gene expression in CA3 might occur at a time possibly corresponding to the late appearance of the first clinical symptoms. We also found earlier changes in expression of schizophrenia susceptibility genes in CA1, which might be linked to prodromal psychotic symptoms. A number of schizophrenia susceptibility genes including APOE, BDNF, MTHFR and SLC6A4 are involved in other disorders, and thus likely contribute to nonspecific changes in hippocampal structure and function that must be combined with the dysregulation of other genes in order to lead to schizophrenia pathogenesis.
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Lorusso ML, Civati F, Molteni M, Turconi AC, Bresolin N, D'Angelo MG. Specific profiles of neurocognitive and reading functions in a sample of 42 Italian boys with Duchenne Muscular Dystrophy. Child Neuropsychol 2012; 19:350-69. [PMID: 22385039 DOI: 10.1080/09297049.2012.660912] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
A group of 42 Italian boys with Duchenne Muscular Dystrophy was compared with a control group of 10 boys with Spinal Muscular Atrophy and Osteogenesis Imperfecta on tests assessing general intellectual ability, language, neuropsychological functions, and reading skills with the aim of describing a comprehensive profile of the various functions and investigating their interrelationships. The influence of general intellectual level on performance was analyzed. Further, correlations between various neuropsychological measures and language performances were computed for the group with Duchenne Muscular Dystrophy, as well as the correlations between reading scores and other cognitive and linguistic measures. A general lowering in VIQ, PIQ, and FSIQ scores was found to characterize the group with Duchenne Muscular Dystrophy. Expressive language skills were within the normal range, while syntactic and grammatical comprehension were significantly impaired. The presence of below-average reading performances was further confirmed. However, unlike previous studies on irregular orthographies, the present results show that (a) the mild reading difficulties found in the sample essentially concern speed rather than accuracy; (b) they concern word rather than nonword reading; (c) lower reading performances are related to lower scores in general IQ; (d) no correlations emerge with phonological abilities, verbal short-term memory, or working memory, but rather with long-term memory and lexical skills. This may suggest that language-specific effects modulate the cognitive expressions of Duchenne Muscular Dystrophy and raises the possibility that the dysfunctions underlying the reading difficulties observed in affected readers of regular orthographies involve different neurocognitive systems than the cortico-cerebellar circuits usually invoked.
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Affiliation(s)
- Maria Luisa Lorusso
- Department of Neuro-Rehabilitation-II, Unit of Neuropsychology of Developmental Disorders, Scientific Institute IRCCS Eugenio Medea, Bosisio Parini, Lecco, Italy.
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Medial temporal theta/alpha power enhancement precedes successful memory encoding: evidence based on intracranial EEG. J Neurosci 2011; 31:5392-7. [PMID: 21471374 DOI: 10.1523/jneurosci.3668-10.2011] [Citation(s) in RCA: 149] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Not only poststimulus, but also prestimulus neural activity has been shown to be predictive for later successful memory encoding. However, it is still not clear which medial temporal lobe processes precede effective memory formation. Here, our aim was to investigate whether such prestimulus markers for successful memory encoding can be specified based on intracranial recordings directly from the hippocampus and rhinal cortex. For this purpose, we analyzed subsequent memory effects during a continuous word recognition paradigm in 31 presurgical epilepsy patients. We found that rhinal and hippocampal theta and successive alpha power enhancement before word presentation predicted successful memory encoding. Previous studies suggest that stimulus-triggered hippocampal theta activity is particularly related to memory retrieval and activation of a mnemonic context, whereas the alpha rhythm reflects inhibitory top-down control of task processing and executive functioning. In line with these suggestions, we propose that the observed medial temporal theta and alpha power increases before stimulus presentation reflect activation of contextual information and inhibitory top-down control processes preparing for stimulus-triggered memory processing.
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Kozora E, Brown MS, Filley CM, Zhang L, Miller DE, West SG, Pelzman J, Arciniegas DB. Memory impairment associated with neurometabolic abnormalities of the hippocampus in patients with non-neuropsychiatric systemic lupus erythematosus. Lupus 2011; 20:598-606. [DOI: 10.1177/0961203310392425] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Objective: Memory impairment is common in patients with systemic lupus erythematosus (SLE). This study examined hippocampal volumes and neurometabolic alterations in relation to memory function in SLE patients without a history of neuropsychiatric syndromes (nonNPSLE). Methods: Subjects included 81 nonNPSLE patients and 34 healthy controls. Volumetric magnetic resonance imaging and magnetic resonance spectroscopy of the right and left hippocampal areas (RH, LH) were performed. Verbal and visual memory tests were administered and a Memory Impairment Index (MII) was derived from standardized tests. Results: Higher memory impairment (MII) was correlated with lower RH glutamate + glutamine/creatine ( p = 0.009) and lower RH N-acetylaspartic acid/creatine ( p = 0.012) in nonNPSLE patients. A trend for a negative correlation between RH and LH volumes and MII was evident for absolute hippocampal volumes. Lower RH glutamate + glutamine/creatine was also correlated with worse performance in a mean visual memory index ( p = 0.017). Conclusions: An association between reduced memory and lower N-acetylaspartic acid/creatine in the RH suggests neuronal damage in nonNPSLE patients with very mild and early disease. Alterations in glutamate + glutamine/creatine further indicate early metabolic changes in nonNPSLE are related to memory impairment, a finding that might suggest that memory impairment relates to presynaptic glutamatergic dysfunction in the hippocampus.
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Affiliation(s)
- E Kozora
- Department of Medicine, National Jewish Health, Denver, CO, USA
- Department of Neurology, University of Colorado Denver School of Medicine, Denver, CO, USA
- Department of Psychiatry, University of Colorado Denver School of Medicine, Denver, CO, USA
| | - MS Brown
- Department of Radiology, University of Colorado Denver School of Medicine, Denver, CO, USA
| | - CM Filley
- Department of Neurology, University of Colorado Denver School of Medicine, Denver, CO, USA
- Department of Psychiatry, University of Colorado Denver School of Medicine, Denver, CO, USA
- Denver Veterans Affairs Medical Center, Denver, CO, USA
| | - L Zhang
- Department of Medicine, National Jewish Health, Denver, CO, USA
| | - DE Miller
- Department of Radiology, University of Colorado Denver School of Medicine, Denver, CO, USA
| | - SG West
- Department of Rheumatology, University of Colorado Denver School of Medicine, Denver, CO, USA
| | - J Pelzman
- Department of Medicine, National Jewish Health, Denver, CO, USA
| | - DB Arciniegas
- Department of Neurology, University of Colorado Denver School of Medicine, Denver, CO, USA
- Department of Psychiatry, University of Colorado Denver School of Medicine, Denver, CO, USA
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Perouansky M, Pearce RA. How we recall (or don't): the hippocampal memory machine and anesthetic amnesia. Can J Anaesth 2010; 58:157-66. [PMID: 21170624 DOI: 10.1007/s12630-010-9417-y] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2010] [Accepted: 10/26/2010] [Indexed: 11/25/2022] Open
Abstract
PURPOSE The hippocampal formation occupies a central position for the processing of sensory input into learned, remembered, and consciously retrievable information. The mechanisms by which anesthetic drugs interfere with these processes are now emerging. We review the current understanding of the role of the hippocampal formation in the generation of memory traces and how anesthetics might interfere with its function. CLINICAL FEATURES Intraoperative amnesia is a desired endpoint of general anesthesia from the perspective of both the patient and the practitioner. "Intraoperative awareness with recall" can result when learning and memory do occur. In addition, anesthetics are capable of inducing a state of "conscious amnesia" that can provide insight into the workings of the brain and might be useful clinically. CONCLUSIONS Anesthesiologists routinely induce the most fascinating pharmacologic effects in existence, the reversible interference of anesthetics with higher cognitive functions. Understanding how the drugs in our custody exert their effects should be our contribution to mankind's universal knowledge base.
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Affiliation(s)
- Misha Perouansky
- Department of Anesthesiology, University of Wisconsin School of Medicine and Public Health, B6/319 Clinical Science Center, 600 Highland Avenue, Madison, WI 53792-3272, USA.
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Kuang H, Lin L, Tsien JZ. Temporal dynamics of distinct CA1 cell populations during unconscious state induced by ketamine. PLoS One 2010; 5:e15209. [PMID: 21165147 PMCID: PMC2999569 DOI: 10.1371/journal.pone.0015209] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2010] [Accepted: 10/29/2010] [Indexed: 01/21/2023] Open
Abstract
Ketamine is a widely used dissociative anesthetic which can induce some psychotic-like symptoms and memory deficits in some patients during the post-operative period. To understand its effects on neural population dynamics in the brain, we employed large-scale in vivo ensemble recording techniques to monitor the activity patterns of simultaneously recorded hippocampal CA1 pyramidal cells and various interneurons during several conscious and unconscious states such as awake rest, running, slow wave sleep, and ketamine-induced anesthesia. Our analyses reveal that ketamine induces distinct oscillatory dynamics not only in pyramidal cells but also in at least seven different types of CA1 interneurons including putative basket cells, chandelier cells, bistratified cells, and O-LM cells. These emergent unique oscillatory dynamics may very well reflect the intrinsic temporal relationships within the CA1 circuit. It is conceivable that systematic characterization of network dynamics may eventually lead to better understanding of how ketamine induces unconsciousness and consequently alters the conscious mind.
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Affiliation(s)
- Hui Kuang
- Key Laboratories of MOE and STCSM, Shanghai Institute of Brain Functional Genomics, East China Normal University, Shanghai, China
- School of Medicine, Brain and Behavior Discovery Institute, Georgia Health Sciences University, Augusta, Georgia, United States of America
| | - Longnian Lin
- Key Laboratories of MOE and STCSM, Shanghai Institute of Brain Functional Genomics, East China Normal University, Shanghai, China
| | - Joe Z. Tsien
- School of Medicine, Brain and Behavior Discovery Institute, Georgia Health Sciences University, Augusta, Georgia, United States of America
- * E-mail:
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Daumann J, Wagner D, Heekeren K, Neukirch A, Thiel CM, Gouzoulis-Mayfrank E. Neuronal correlates of visual and auditory alertness in the DMT and ketamine model of psychosis. J Psychopharmacol 2010; 24:1515-24. [PMID: 19304859 DOI: 10.1177/0269881109103227] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Deficits in attentional functions belong to the core cognitive symptoms in schizophrenic patients. Alertness is a nonselective attention component that refers to a state of general readiness that improves stimulus processing and response initiation. The main goal of the present study was to investigate cerebral correlates of alertness in the human 5HT(2A) agonist and N-methyl-D-aspartic acid (NMDA) antagonist model of psychosis. Fourteen healthy volunteers participated in a randomized double-blind, cross-over event-related functional magnetic resonance imaging (fMRI) study with dimethyltryptamine (DMT) and S-ketamine. A target detection task with cued and uncued trials in both the visual and the auditory modality was used. Administration of DMT led to decreased blood oxygenation level-dependent response during performance of an alertness task, particularly in extrastriate regions during visual alerting and in temporal regions during auditory alerting. In general, the effects for the visual modality were more pronounced. In contrast, administration of S-ketamine led to increased cortical activation in the left insula and precentral gyrus in the auditory modality. The results of the present study might deliver more insight into potential differences and overlapping pathomechanisms in schizophrenia. These conclusions must remain preliminary and should be explored by further fMRI studies with schizophrenic patients performing modality-specific alertness tasks.
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Affiliation(s)
- J Daumann
- Department of Psychiatry and Psychotherapy, University of Cologne, Germany.
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Onur OA, Schlaepfer TE, Kukolja J, Bauer A, Jeung H, Patin A, Otte DM, Shah NJ, Maier W, Kendrick KM, Fink GR, Hurlemann R. The N-methyl-D-aspartate receptor co-agonist D-cycloserine facilitates declarative learning and hippocampal activity in humans. Biol Psychiatry 2010; 67:1205-11. [PMID: 20303474 DOI: 10.1016/j.biopsych.2010.01.022] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/10/2009] [Revised: 01/12/2010] [Accepted: 01/22/2010] [Indexed: 10/19/2022]
Abstract
BACKGROUND The N-methyl-D-aspartate receptor (NMDAR) is critical for learning-related synaptic plasticity in amygdala and hippocampus. As a consequence, there is considerable interest in drugs targeting this receptor to help enhance amygdala- and hippocampus-dependent learning. A promising candidate in this respect is the NMDAR glycine-binding site partial agonist D-cycloserine (DCS). Accumulating clinical evidence indicates the efficacy of DCS in the facilitation of amygdala-dependent fear extinction learning in patients with phobic, social anxiety, panic, and obsessive-compulsive disorder. An important unresolved question though is whether the use of DCS can also facilitate hippocampus-dependent declarative learning in healthy people as opposed to being restricted to the fear memory domain. METHODS In the present study, we investigated whether or not DCS can facilitate hippocampus-dependent declarative learning. We have therefore combined functional magnetic resonance imaging with two different declarative learning tasks and cytoarchitectonic probabilistic mapping of the hippocampus and its major subdivisions in 40 healthy volunteers administered either a 250 mg single oral dose of DCS or a placebo. RESULTS We found that DCS facilitates declarative learning as well as blood-oxygen level dependent activity levels in the probabilistically defined cornu ammonis region of the hippocampus. The absence of activity changes in visual control areas underscores the specific action of DCS in the hippocampal cornu ammonis region. CONCLUSIONS Our findings highlight NMDAR glycine-binding site partial agonism as a promising pharmacological mechanism for facilitating declarative learning in healthy people.
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Affiliation(s)
- Oezguer A Onur
- Department of Psychiatry, University of Bonn, Bonn, Germany
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Van Petten C, Federmeier KD, Holcomb PJ. For distinguished contributions to psychophysiology: Marta Kutas. Psychophysiology 2010; 47:403-9. [DOI: 10.1111/j.1469-8986.2009.00930.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Olichney JM, Chan S, Wong LM, Schneider A, Seritan A, Niese A, Yang JC, Laird K, Teichholtz S, Khan S, Tassone F, Hagerman R. Abnormal N400 word repetition effects in fragile X-associated tremor/ataxia syndrome. Brain 2010; 133:1438-50. [PMID: 20410144 DOI: 10.1093/brain/awq077] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Fragile X-associated tremor/ataxia syndrome, a neurodegenerative disorder associated with premutation alleles (55-200 CGG repeats) of the FMR1 gene, affects many carriers in late-life. Patients with fragile X-associated tremor/ataxia syndrome typically have cerebellar ataxia, intranuclear inclusions in neurons and astrocytes, as well as cognitive impairment. Dementia can also be present with cognitive deficits that are as severe as in Alzheimer's disease, however frontosubcortical type impairment is more pronounced in fragile X-associated tremor/ataxia syndrome. We sought to characterize the P600 and N400 word repetition effects in patients with fragile X-associated tremor/ataxia syndrome, using an event-related potential word repetition paradigm with demonstrated sensitivity to very early Alzheimer's disease. We hypothesized that the fragile X-associated tremor/ataxia syndrome-affected participants with poor declarative verbal memory would have pronounced abnormalities in the P600 repetition effect. In the event-related potential experiment, subjects performed a category decision task whilst an electroencephalogram was recorded. Auditory category statements were each followed by an associated visual target word (50% 'congruous' category exemplars, 50% 'incongruous' nouns). Two-thirds of the stimuli (category statement-target word pairs) were repeated, either at short-lag (approximately 10-40 s) or long-lag (approximately 100-140 s). The N400 and P600 amplitude data were submitted to split-plot analyses of variance. These analyses of variance showed a highly significant reduction of the N400 repetition effect (F = 22.5, P < 0.001), but not of the P600 repetition effect, in mild fragile X-associated tremor/ataxia syndrome (n = 32, mean age = 68.7, mean Mini-Mental State Examination score = 26.8). Patients with fragile X-associated tremor/ataxia syndrome had significantly smaller late positive amplitude (550-800 ms post-stimulus onset) to congruous words (P = 0.04 for group effect). Reduced P600 repetition effect amplitude was associated with poorer recall within fragile X-associated tremor/ataxia syndrome patients (r = 0.66) and across all subjects (r = 0.52). Larger P600 amplitude to new congruous words also correlated significantly with higher free recall scores (r = 0.37, P < 0.01) across all subjects. We found a correlation between the amplitude of late positivity and CGG repeat length in those with fragile X-associated tremor/ataxia syndrome (r = 0.47, P = 0.006). Higher levels of FMR1 mRNA were associated with smaller N400s to incongruous words and larger positive amplitudes (between 300 and 500 ms) to congruous words. In conclusion, event-related potential word repetition effects appear sensitive to the cognitive dysfunction present in patients with mild fragile X-associated tremor/ataxia syndrome. Their more severe reduction in N400 repetition effect, than P600, is in contrast to the reverse pattern reported in amnestic mild cognitive impairment and incipient Alzheimer's disease (Olichney et al., 2008).
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Affiliation(s)
- John M Olichney
- Department of Neurology, University of California Davis, Davis, CA 95618, USA.
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Jing M, Shingo T, Yasuhara T, Kondo A, Morimoto T, Wang F, Baba T, Yuan WJ, Tajiri N, Uozumi T, Murakami M, Tanabe M, Miyoshi Y, Zhao S, Date I. The combined therapy of intrahippocampal transplantation of adult neural stem cells and intraventricular erythropoietin-infusion ameliorates spontaneous recurrent seizures by suppression of abnormal mossy fiber sprouting. Brain Res 2009; 1295:203-17. [PMID: 19646969 DOI: 10.1016/j.brainres.2009.07.079] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2009] [Revised: 07/21/2009] [Accepted: 07/22/2009] [Indexed: 11/27/2022]
Abstract
Adult neural stem cells (NSCs) possess the potentials to self-renew and exert neuroprotection. In this study, we examined whether adult NSCs had anti-epileptic effects in rats with status epilepticus (SE) induced by kainic acid (KA) and whether co-administration of erythropoietin (EPO) enhanced anti-epileptic effects or cell survival. Adult NSCs were transplanted into KA-lesioned hippocampus with or without intracerebroventricular EPO infusion. Electronic encephalography (EEG) was recorded for 3 weeks after transplantation. The frequency of abnormal spikes in rats with NSC transplantation decreased significantly compared to those of rats without NSC transplantation. Most of the transplanted NSCs differentiated into GFAP-positive astrocytes. EPO infusion significantly enhanced the survival of NSCs, but not neuronal differentiation or migration. NSC transplantation increased the number of neuropeptide Y (NPY) and glutamic acid decarboxylase 67 (GAD67)-positive interneurons. NSC transplantation also suppressed mossy fiber sprouting into the inner molecular layer with subsequent reduction of hippocampal excitability, which finally prevented the development of spontaneous recurrent seizures in adult rats after KA-induced SE. This study might shed light on the cytoarchitectural mechanisms of temporal lobe epilepsy as well as clarify the effect of adult NSC transplantation with intracerebroventricular EPO infusion for temporal lobe epilepsy.
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Affiliation(s)
- Meng Jing
- Department of Neurological Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences 2-5-1, Shikata-cho, Okayama 700-8558, Japan
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Hamed SA. The aspects and mechanisms of cognitive alterations in epilepsy: the role of antiepileptic medications. CNS Neurosci Ther 2009; 15:134-56. [PMID: 19254331 PMCID: PMC6494068 DOI: 10.1111/j.1755-5949.2008.00062.x] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Epilepsy is a major health problem. Several studies suggest a significant influence of epilepsy and its treatment on dynamic and functional properties of brain activity. Epilepsy can adversely affect mental development, cognition, and behavior. Epileptic patients may experience reduced intelligence, attention, and problems in memory, language, and frontal executive functions. Neuropsychological, functional, and quantitative neuroimaging studies revealed that epilepsy affect the brain as a whole. Mechanisms of epilepsy-related cognitive dysfunction are poorly delineated. Cognitive deficits with epilepsy may be transient, persistent, or progressive. Transient disruption of cognitive encoding processes may occur with paroxysmal focal or generalized epileptic discharges, whereas epileptogenesis-related neuronal plasticity, reorganization, sprouting, and impairment of cellular metabolism are fundamental determinants for progressive cognitive deterioration. Also antiepileptic drugs (AEDs) have differential, reversible, and sometimes cumulative cognitive adverse consequences. AEDs not only reduce neuronal irritability but also may impair neuronal excitability, neurotransmitter release, enzymes, and factors critical for information processing and memory. The present article serves as an overview of recent studies in adult and childhood epilepsy literatures present in PubMed that highlighted cognitive evaluation in epilepsy field (publications till 2008 were checked). We also checked the reference lists of the retrieved studies for additional reports of relevant studies, in addition to our experience in this field. Our search revealed that although the aspects of cognitive dysfunction, risk factors, and consequences have been explored in many studies; however, the mechanisms of contribution of epilepsy-related variables, including AEDs, to patients' cognition are largely unexplored. In this review, we discussed the differential effect of AEDs in mature and immature brains and the known mechanisms underlying epilepsy and AEDs adverse effects on cognition. The nature, timing, course, and mechanisms of cognitive alteration with epilepsy and its medications are of considerable clinical and research implications.
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Affiliation(s)
- Sherifa A Hamed
- Department of Neurology and Psychiatry, Assiut University Hospital, Assiut, Egypt.
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Fell J, Ludowig E, Rosburg T, Axmacher N, Elger CE. Phase-locking within human mediotemporal lobe predicts memory formation. Neuroimage 2008; 43:410-9. [DOI: 10.1016/j.neuroimage.2008.07.021] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2008] [Revised: 06/19/2008] [Accepted: 07/07/2008] [Indexed: 10/21/2022] Open
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Daumann J, Heekeren K, Neukirch A, Thiel CM, Möller-Hartmann W, Gouzoulis-Mayfrank E. Pharmacological modulation of the neural basis underlying inhibition of return (IOR) in the human 5-HT2A agonist and NMDA antagonist model of psychosis. Psychopharmacology (Berl) 2008; 200:573-83. [PMID: 18649072 DOI: 10.1007/s00213-008-1237-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Accepted: 06/11/2008] [Indexed: 10/21/2022]
Abstract
RATIONALE Attentional deficits are common symptoms in schizophrenia. Recent evidence suggests that schizophrenic patients show abnormalities in spatial orienting of attention, particularly a deficit of inhibition of return (IOR). IOR is mostly thought to reflect an automatic, inhibitory mechanism protecting the organism from redirecting attention to previously scanned, insignificant locations. Pharmacologic challenges with hallucinogens have been used as models for psychosis. OBJECTIVES The aim of this study was to investigate the neural correlates underlying orienting of attention in the human N-methyl-D-aspartic acid antagonist and 5-HT2A agonist models of psychosis. MATERIALS AND METHODS Fourteen healthy volunteers participated in a randomized, double-blind, cross-over event-related functional magnetic resonance imaging (fMRI) study with dimethyltryptamine (DMT) and S-ketamine. We administered a covert orienting of attention task with nonpredictive peripheral cues, and we scanned the subjects on two separate days at least 14 days apart with a placebo and a verum condition on each day. RESULTS DMT, but not S-ketamine, slowed down reaction times significantly. IOR was blunted after DMT, but not after S-ketamine. Relative to placebo, S-ketamine increased activation in the IOR condition in the right superior frontal gyrus, left superior temporal gyrus, and right midfrontal frontal gyrus. CONCLUSIONS The discrepancy between the behavioral and functional imaging outcome indicates that pharmacological fMRI might be a sensitive tool to detect drug-modulated blood oxygenation level-dependent signal changes in the absence of behavioral abnormalities. Our findings might help to further clarify the contradictory findings of IOR in schizophrenic patients and might, thus, shed more light on possible differential pathomechanisms of schizophrenic symptoms.
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Affiliation(s)
- Jörg Daumann
- Department of Psychiatry and Psychotherapy, University of Cologne, Kerpener Strasse 62, 50924 Cologne, Germany.
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Frigeri A, Iacobas DA, Iacobas S, Nicchia GP, Desaphy JF, Camerino DC, Svelto M, Spray DC. Effect of microgravity on gene expression in mouse brain. Exp Brain Res 2008; 191:289-300. [PMID: 18704384 PMCID: PMC2651838 DOI: 10.1007/s00221-008-1523-5] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2008] [Accepted: 07/24/2008] [Indexed: 01/27/2023]
Abstract
Changes in gravitational force such as that experienced by astronauts during space flight induce a redistribution of fluids from the caudad to the cephalad portion of the body together with an elimination of normal head-to-foot hydrostatic pressure gradients. To assess brain gene profile changes associated with microgravity and fluid shift, a large-scale analysis of mRNA expression levels was performed in the brains of 2-week control and hindlimb-unloaded (HU) mice using cDNA microarrays. Although to different extents, all functional categories displayed significantly regulated genes indicating that considerable transcriptomic alterations are induced by HU. Interestingly, the TIC class (transport of small molecules and ions into the cells) had the highest percentage of up-regulated genes, while the most down-regulated genes were those of the JAE class (cell junction, adhesion, extracellular matrix). TIC genes comprised 16% of those whose expression was altered, including sodium channel, nonvoltage-gated 1 beta (Scnn1b), glutamate receptor (Grin1), voltage-dependent anion channel 1 (Vdac1), calcium channel beta 3 subunit (Cacnb3) and others. The analysis performed by GeneMAPP revealed several altered protein classes and functional pathways such as blood coagulation and immune response, learning and memory, ion channels and cell junction. In particular, data indicate that HU causes an alteration in hemostasis which resolves in a shift toward a more hyper-coagulative state with an increased risk of venous thrombosis. Furthermore, HU treatment seems to impact on key steps of synaptic plasticity and learning processes.
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Affiliation(s)
- Antonio Frigeri
- Department of General and Environmental Physiology, Centre of Excellence in Comparative Genomics (CEGBA), University of Bari, via Amendola 165/A, 70126 Bari, Italy, e-mail:
| | - Dumitru A. Iacobas
- Department of Neuroscience, Albert Einstein College of Medicine, 1410 Pelham Pkwy S, Bronx, NY 10464, USA
| | - Sanda Iacobas
- Department of Neuroscience, Albert Einstein College of Medicine, 1410 Pelham Pkwy S, Bronx, NY 10464, USA
| | - Grazia Paola Nicchia
- Department of General and Environmental Physiology, Centre of Excellence in Comparative Genomics (CEGBA), University of Bari, via Amendola 165/A, 70126 Bari, Italy, e-mail:
| | | | | | - Maria Svelto
- Department of General and Environmental Physiology, Centre of Excellence in Comparative Genomics (CEGBA), University of Bari, via Amendola 165/A, 70126 Bari, Italy, e-mail:
| | - David C. Spray
- Department of Neuroscience, Albert Einstein College of Medicine, 1410 Pelham Pkwy S, Bronx, NY 10464, USA
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Beck H, Elger CE. Epilepsy research: a window onto function to and dysfunction of the human brain. DIALOGUES IN CLINICAL NEUROSCIENCE 2008. [PMID: 18472480 PMCID: PMC3181865 DOI: 10.31887/dcns.2008.10.1/hbeck] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
As one of the most common neurological disorders, epilepsy has devastating behavioral, social, and occupational consequences and is associated with accumulating brain damage and neurological deficits. Epilepsy comprises a large number of syndromes, which vary greatly respect to their etiology and clinical features, but share the characteristic clinical hallmark of epilepsy recurrent spontaneous seizures. Research aimed at understanding the genetic, molecular, and cellular basis of epilepsy has to integrate various research approaches and techniques ranging from clinical expertise, functional analyses of the system and cellular levels, both in human subjects and rodent models of epilepsy, to human and mouse genetics. This knowledge may then be developed into novel treatment options with better control of seizures andlor fewer side effects. In addition, the study of epilepsy has frequently shed light on basic mechanisms underlying the function and dysfunction of the human brain.
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Affiliation(s)
- Heinz Beck
- Department of Epileptology, University of Bonn Medical Center, Bonn, Germany
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Ludowig E, Trautner P, Kurthen M, Schaller C, Bien CG, Elger CE, Rosburg T. Intracranially recorded memory-related potentials reveal higher posterior than anterior hippocampal involvement in verbal encoding and retrieval. J Cogn Neurosci 2008; 20:841-51. [PMID: 18201126 DOI: 10.1162/jocn.2008.20507] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
The human hippocampus is essential for both encoding and recollection, but it remains controversial whether there is a functionally different involvement of anterior versus posterior parts of the hippocampus in these memory processes. In the present study, we examined encoding and retrieval processes via intrahippocampal recordings in 27 patients with unilateral temporal lobe epilepsy. Multicontact depth electrodes were implanted along the longitudinal axis of the hippocampus as part of the presurgical evaluation. In a continuous word recognition test, subjects had to indicate whether words were new or already presented. Recognized old words, as compared to new words, resulted in a larger P600 component, as well as in a larger late negative component (LNC, 600-900 msec). In addition, subsequently remembered words elicited a larger positivity (400 to 900 msec) than later forgotten words. We found differences concerning the distribution along the hippocampus for the LNC old-new effect, reflecting successful retrieval, as well as for the subsequent memory effect, reflecting successful encoding. Both effects were larger the further posterior an electrode was located in the hippocampus. Findings are suggestive for a predominant posterior hippocampal involvement in both verbal encoding and retrieval.
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Affiliation(s)
- Eva Ludowig
- Department of Epileptology, University of Bonn, Bonn, Germany.
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Limbic event-related potentials to words and pictures in the presurgical evaluation of temporal lobe epilepsy. Epilepsy Res 2008; 78:207-15. [DOI: 10.1016/j.eplepsyres.2007.12.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2007] [Revised: 11/20/2007] [Accepted: 12/07/2007] [Indexed: 11/18/2022]
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Hamed SA. Neuronal plasticity: implications in epilepsy progression and management. Drug Dev Res 2008. [DOI: 10.1002/ddr.20217] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
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Abstract
Progesterone, or rather its neuroactive metabolite allopregnanolone, modulates amygdala activity and thereby influences anxiety. Cognition and, in particular, memory are also altered by allopregnanolone. In the present study, we investigated whether allopregnanolone modulates memory for biologically salient stimuli by influencing amygdala activity, which in turn may affect neural processes in other brain regions. A single progesterone dose was administered orally to healthy young women in a double-blind, placebo-controlled, crossover design, and participants were asked to memorize and recognize faces while undergoing functional magnetic resonance imaging. Progesterone decreased recognition accuracy without affecting reaction times. The imaging results show that the amygdala, hippocampus, and fusiform gyrus supported memory formation. Importantly, progesterone decreased responses to faces in the amygdala and fusiform gyrus during memory encoding, whereas it increased hippocampal responses. The progesterone-induced decrease in neural activity in the amygdala and fusiform gyrus predicted the decrease in memory performance across subjects. However, progesterone did not modulate the differential activation between subsequently remembered and subsequently forgotten faces in these areas. A similar pattern of results was observed in the fusiform gyrus and prefrontal cortex during memory retrieval. These results suggest that allopregnanolone impairs memory by reducing the recruitment of those brain regions that support memory formation and retrieval. Given the important role of the amygdala in the modulation of memory, these results suggest that allopregnanolone alters memory by influencing amygdala activity, which in turn may affect memory processes in other brain regions.
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Okanishi T, Mori Y, Kibe T, Takahashi Y, Saito Y, Maegaki Y, Yokochi K. Refractory epilepsy accompanying acute encephalitis with multifocal cortical lesions: possible autoimmune etiology. Brain Dev 2007; 29:590-4. [PMID: 17442514 DOI: 10.1016/j.braindev.2007.02.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/30/2006] [Revised: 01/31/2007] [Accepted: 02/10/2007] [Indexed: 11/27/2022]
Abstract
We report on a 14-year-old male suffering from acute encephalitis, whose clinical course met the criteria for acute encephalopathy with refractory, repetitive partial seizures (AERRPS). He presented with extremely refractory partial and secondary generalized seizures, and required high-dose barbiturate infusion therapy for 57 days under mechanical ventilation. Seven weeks after onset, the seizures were ameliorated by treatment with sodium bromide, carbamazepine, clobazam, and high-dose phenobarbital. Magnetic resonance imaging on day 14 of admission showed multifocal cortical lesions scattered in the bilateral hemispheres; these disappeared on day 34. Diffuse and mild atrophy of the cerebral cortex, and moderate atrophy of the hippocampus, appeared by day 61. Serum anti-glutamate receptor epsilon2 autoantibodies were detected on day 2. The patient was discharged after 113 days of admission with intractable epilepsy, memory disability, and regression of intelligence. We discuss the etiological significance of the multifocal lesions, which are unusual findings on neuroimaging of AERRPS.
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Affiliation(s)
- Tohru Okanishi
- Division of Child Neurology, Institute of Neurological Sciences, Faculty of Medicine, Tottori University, 36-1 Yonago 683-8504, Japan.
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Abstract
Intracranial recordings of cognitive potentials within the human hippocampal system have identified N400 potentials in the anterior mesial temporal lobe (AMTL-N400) that correlate with verbal memory performance and are associated with novelty detection. Their amplitudes to "new" but not "old" words in a verbal recognition task correlate with the neuronal density of the hippocampal CA1-region and can be reduced selectively by the NMDA-receptor blocker ketamine. Moreover, it could be shown that NMDA-receptor dependent long-term potentiation (LTP), a form of synaptic plasticity with Hebbian characteristics, can be readily induced in human hippocampal slices but not in patients with hippocampal sclerosis. In these latter patients, we also found a reduction of AMTL-N400 amplitudes similar to the one induced by ketamine. In addition, we could show that hippocampal novelty detection is associated with successful encoding for declarative memory. Together, our findings suggest that successful encoding for declarative memory is at least in part mediated by NMDA-receptor dependent novelty detection within the human hippocampal system.
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Daselaar SM, Fleck MS, Cabeza R. Triple Dissociation in the Medial Temporal Lobes: Recollection, Familiarity, and Novelty. J Neurophysiol 2006; 96:1902-11. [PMID: 16738210 DOI: 10.1152/jn.01029.2005] [Citation(s) in RCA: 342] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Memory for past events may be based on retrieval accompanied by specific contextual details (recollection) or on the feeling that an item is old (familiarity) or new (novelty) in the absence of contextual details. There are indications that recollection, familiarity, and novelty involve different medial temporal lobe subregions, but available evidence is scarce and inconclusive. Using functional magnetic resonance imaging (MRI), we isolated retrieval-related activity associated with recollection, familiarity, and novelty by distinguishing between linear and nonlinear oldness functions derived from recognition confidence levels. Within the medial temporal lobes (MTLs), we found a triple dissociation among the posterior half of the hippocampus, which was associated with recollection, the posterior parahippocampal gyrus, which was associated with familiarity, and anterior half of the hippocampus and rhinal regions, which were associated with novelty. Furthermore, multiple regression analyses based on individual trial activity showed that all three memory signals, i.e., recollection, familiarity, and novelty, make significant and independent contributions to recognition memory performance. Finally, functional dissociations among recollection, familiarity, and novelty were also found in posterior midline, left parietal cortex, and prefrontal cortex regions. This is the first study to reveal a triple dissociation within the MTL associated with distinct retrieval processes. This finding has direct implications for current memory models.
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Affiliation(s)
- S M Daselaar
- Swammerdam Institute for Life Sciences, Faculty of Science, University of Amsterdam, Amsterdam, The Netherlands.
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Affiliation(s)
- Christian E Elger
- Department of Epileptology, University of Bonn Medical Center, Germany
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Morgan CJA, Rossell SL, Pepper F, Smart J, Blackburn J, Brandner B, Curran HV. Semantic priming after ketamine acutely in healthy volunteers and following chronic self-administration in substance users. Biol Psychiatry 2006; 59:265-72. [PMID: 16140283 DOI: 10.1016/j.biopsych.2005.06.018] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/13/2004] [Revised: 04/13/2005] [Accepted: 06/10/2005] [Indexed: 11/30/2022]
Abstract
BACKGROUND Ketamine is used acutely as a model of schizophrenia. It has been suggested that chronic ketamine may also mimic aspects of this disorder, in particular impaired cognitive function. As semantic processing deficits are considered central to cognitive impairments in schizophrenia, this study aimed to characterize semantic impairments following both acute and chronic ketamine. METHODS We examined the acute effects of two doses of ketamine (Experiment 1) using a double-blind, placebo-controlled, independent group design with 48 volunteers. Ketamine's chronic effects (Experiment 2) were explored in 16 ketamine users and 16 poly-drug controls. A semantic priming task with a frequency (high and low) and stimulus onset asynchrony (SOA: short-200 msec, long-750 msec) manipulation was used. RESULTS In Experiment 1, acute ketamine produced inverse priming at the long SOA. In Experiment 2, ketamine users showed inverse priming for low-frequency words at the long SOA compared to poly-drug controls. CONCLUSIONS The inverse priming effect at the long SOA induced by acute ketamine was indicative of controlled processing impairments. In ketamine users, there was also an indication of controlled processing impairments. Decreased priming for low-frequency words suggested that long-term ketamine abuse results in damage to the semantic store.
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Affiliation(s)
- Celia J A Morgan
- Clinical Psychopharmacology Unit, University College London, London WC1E 6BT, United Kingdom.
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