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Pattern completion and hippocampus

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https://www.readbyqxmd.com/read/28814638/field-repetition-and-local-mapping-in-the-hippocampus-and-medial-entorhinal-cortex
#1
Roddy M Grieves, Éléonore Duvelle, Emma R Wood, Paul Anthony Dudchenko
Hippocampal place cells support spatial cognition and are thought to form the neural substrate of a global 'cognitive map'. A widely held view is that parts of the hippocampus also underlie the ability to separate patterns, or to provide different neural codes for distinct environments. However, a number of studies have shown that in environments composed of multiple, repeating compartments, place cells and other spatially modulated neurons show the same activity in each local area. This repetition of firing fields may reflect pattern completion, and may make it difficult for animals to distinguish similar local environments...
August 16, 2017: Journal of Neurophysiology
https://www.readbyqxmd.com/read/28810973/the-influence-of-combat-experience-on-psychologically-healthy-soldiers-attentiveness-to-environmental-threats
#2
Bethany Ranes, Chris P Long, Stephanie Traynham, Amanda Hayes
INTRODUCTION: In contrast to previous research that has primarily examined how psychological disorders (e.g., post-traumatic stress disorder [PTSD], anxiety) are affected by and affect individuals' threat perceptions, this study examines the relationship between combat experience and threat-monitoring in psychologically healthy Soldiers. Existing research has established how prolonged or intense experiences with war-related stressors can lead individuals to undergo an unconscious fear-conditioning process that affects the circuitry of the prefrontal cortex, hippocampus, amygdala, and anterior cingulate cortex regions of the brain...
July 2017: Military Medicine
https://www.readbyqxmd.com/read/28776200/regulator-of-g-protein-signaling-14-rgs14-is-expressed-pre-and-postsynaptically-in-neurons-of-hippocampus-basal-ganglia-and-amygdala-of-monkey-and-human-brain
#3
Katherine E Squires, Kyle J Gerber, Jean-Francois Pare, Mary Rose Branch, Yoland Smith, John R Hepler
Regulator of G protein signaling 14 (RGS14) is a multifunctional signaling protein primarily expressed in mouse pyramidal neurons of hippocampal area CA2 where it regulates synaptic plasticity important for learning and memory. However, very little is known about RGS14 protein expression in the primate brain. Here, we validate the specificity of a new polyclonal RGS14 antibody that recognizes not only full-length RGS14 protein in primate, but also lower molecular weight forms of RGS14 protein matching previously predicted human splice variants...
August 3, 2017: Brain Structure & Function
https://www.readbyqxmd.com/read/28774647/discrimination-of-a-medial-functional-module-within-the-temporal-lobe-using-an-effective-connectivity-model-a-ccep-study
#4
Julien Krieg, Laurent Koessler, Jacques Jonas, Sophie Colnat-Coulbois, Jean-Pierre Vignal, Christian G Bénar, Louis G Maillard
The temporal lobe is classically divided in two functional systems: the ventral visual pathway and the medial temporal memory system. However, their functional separation has been challenged by studies suggesting that the medial temporal lobe could be best understood as an extension of the hierarchically organized ventral visual pathway. Our purpose was to investigate (i) whether cerebral regions within the temporal lobe could be grouped into distinct functional assemblies, and (ii) which regions were central within these functional assemblies...
July 31, 2017: NeuroImage
https://www.readbyqxmd.com/read/28760565/familiarity-and-recollection-vs-representational-models-of-medial-temporal-lobe-structures-a-single-case-study
#5
Emilie Lacot, Stéphane Vautier, Stefan Kőhler, Jérémie Pariente, Chris B Martin, Michèle Puel, Jean-Albert Lotterie, Emmanuel J Barbeau
Although it is known that medial temporal lobe (MTL) structures support declarative memory, the fact these structures have different architectonics and circuitry suggests they may also play different functional roles. Selective lesions of MTL structures offer an opportunity to understand these roles. We report, in this study, on JMG, a patient who presents highly unusual lesions that completely affected all MTL structures except for the right hippocampus and parts of neighbouring medial parahippocampal cortex...
July 29, 2017: Neuropsychologia
https://www.readbyqxmd.com/read/28755546/temporal-spatial-characteristics-of-phase-amplitude-coupling-in-electrocorticogram-for-human-temporal-lobe-epilepsy
#6
Ruihua Zhang, Ye Ren, Chunyan Liu, Na Xu, Xiaoli Li, Fengyu Cong, Tapani Ristaniemi, YuPing Wang
OBJECTIVE: Neural activity of the epileptic human brain contains low- and high-frequency oscillations in different frequency bands, some of which have been used as reliable biomarkers of the epileptogenic brain areas. However, the relationship between the low- and high-frequency oscillations in different cortical areas during the period from pre-seizure to post-seizure has not been completely clarified. METHODS: We recorded electrocorticogram data from the temporal lobe and hippocampus of seven patients with temporal lobe epilepsy...
September 2017: Clinical Neurophysiology: Official Journal of the International Federation of Clinical Neurophysiology
https://www.readbyqxmd.com/read/28701481/place-and-grid-cells-in-a-loop-implications-for-memory-function-and-spatial-coding
#7
César Rennó-Costa, Adriano B L Tort
Place cells in the hippocampus and grid cells in the medial entorhinal cortex have different codes for space. However, how one code relates to the other is ill understood. Based on the anatomy of the entorhinal-hippocampal circuitry, we constructed a model of place and grid cells organized in a loop to investigate their mutual influence in the establishment of their codes for space. Using computer simulations, we first replicated experiments in rats that measured place and grid cell activity in different environments, and then assessed which features of the model account for different phenomena observed in neurophysiological data, such as pattern completion and pattern separation, global and rate remapping of place cells and realignment of grid cells...
July 12, 2017: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
https://www.readbyqxmd.com/read/28658048/increased-activation-of-the-hippocampus-during-a-chinese-character-subvocalization-task-in-adults-with-cleft-lip-and-palate-palatoplasty-and-speech-therapy
#8
Wenjing Zhang, Chunlin Li, Long Chen, Xiyue Xing, Xiangyang Li, Zhi Yang, Haiyan Zhang, Renji Chen
This study aimed to explore brain activation in patients with cleft lip and palate (CLP) using a Chinese character subvocalization task, in which the stimuli were selected from a clinical articulation evaluation test. CLP is a congenital disability. Individuals with CLP usually have articulation disorder caused by abnormal lip and palate structure. Previous studies showed that primary somatosensory and motor areas had a significant difference in activation in patients with CLP. However, whether brain activation was restored to a normal level after palatoplasty and speech rehabilitation is not clear...
August 16, 2017: Neuroreport
https://www.readbyqxmd.com/read/28580823/ethanol-and-the-developing-brain-inhibition-of-neuronal-activity-and-neuroapoptosis
#9
Nailya Lotfullina, Roustem Khazipov
Ethanol induces massive neuroapoptosis in the developing brain. One of the main hypotheses that has been put forward to explain the deleterious actions of ethanol in the immature brain involves an inhibition of neuronal activity. Here, we review recent evidence for this hypothesis obtained in the somatosensory cortex and hippocampus of neonatal rodents. In both structures, ethanol strongly inhibits brain activity. At the doses inducing massive neuroapoptosis, ethanol completely suppresses the early activity patterns of spindle-bursts and gamma oscillations in the neocortex and the early sharp-waves in the hippocampus...
June 1, 2017: Neuroscientist: a Review Journal Bringing Neurobiology, Neurology and Psychiatry
https://www.readbyqxmd.com/read/28557507/structural-learning-difficulties-implicate-altered-hippocampal-functioning-in-adults-with-autism-spectrum-disorder
#10
Melanie Ring, Claire L T Derwent, Sebastian B Gaigg, Dermot M Bowler
Structural learning is fundamental to the formation of cognitive maps that are necessary for learning, memory, and spatial navigation. It also enables successful navigation of the social world, which is something that individuals with autism spectrum disorder (ASD) find particularly difficult. To master these situations, a person needs to bind pieces of information to one another and to consider the context in which experiences happen. Such binding is a capacity of the hippocampus. Although altered hippocampal function has for long been suspected to play a role in the etiology of ASD, the relevant evidence has remained inconclusive because few behavioral tests that are known to specifically necessitate preserved hippocampal function have been employed in studies of ASD...
August 2017: Journal of Abnormal Psychology
https://www.readbyqxmd.com/read/28553833/longitudinal-changes-in-brain-metabolic-activity-after-withdrawal-from-escalation-of-cocaine-self-administration
#11
Céline Nicolas, Clovis Tauber, François-Xavier Lepelletier, Sylvie Chalon, Pauline Belujon, Laurent Galineau, Marcello Solinas
The chronic and relapsing nature of addiction suggests that drugs produce persistent adaptations in the brain that make individuals with drug addiction particularly sensitive to drug-related cues and stress and incapable of controlling drug-seeking and drug-taking behavior. In animal models, several long-lasting neuroadaptations have been described. However, few studies have used brain-imaging techniques to provide a complete picture of brain functioning in the course of withdrawal from cocaine. In this study, we allowed rats to self-administer cocaine under short-access (1-h/day) or long-access (6-h/day) conditions and used 2-deoxy-2-((18)F)fluoro-d-glucose ((18)FDG) positron emission tomography (PET) scanning to investigate the longitudinal changes in metabolic activity 1 and 4 weeks after discontinuation of cocaine self-administration...
May 29, 2017: Neuropsychopharmacology: Official Publication of the American College of Neuropsychopharmacology
https://www.readbyqxmd.com/read/28532653/hippocampal-ca1-local-field-potential-oscillations-induced-by-olfactory-cue-of-liked-food
#12
Nifareeda Samerphob, Dania Cheaha, Surapong Chatpun, Ekkasit Kumarnsit
Eating motivation is induced not only by negative energy balance but also food related cues. However, neural processing for acquisition of learned food preference remains to be established. This study aimed to identify hippocampal neural signaling in response to olfactory cue (chocolate scent) after completion of repetitive chocolate sessions. Male Swiss albino mice implanted with intracranial electrode into the hippocampus were used for local field potential (LFP) recording. Animals were given chocolate sessions (a piece of 2g chocolate per each mouse to eat on day 1, 3, 5 and 7)...
May 19, 2017: Neurobiology of Learning and Memory
https://www.readbyqxmd.com/read/28485403/gad1-alternative-transcripts-and-dna-methylation-in-human-prefrontal-cortex-and-hippocampus-in-brain-development-schizophrenia
#13
R Tao, K N Davis, C Li, J H Shin, Y Gao, A E Jaffe, M C Gondré-Lewis, D R Weinberger, J E Kleinman, T M Hyde
Genetic variations and adverse environmental events in utero or shortly after birth can lead to abnormal brain development and increased risk of schizophrenia. γ-Aminobutyric acid (GABA), the major inhibitory neurotransmitter in the mammalian brain, plays a vital role in normal brain development. GABA synthesis is controlled by enzymes derived from two glutamic acid decarboxylase (GAD) genes, GAD1 and GAD2, both of which produce transcript isoforms. While the full-length GAD1 transcript (GAD67) has been implicated in the neuropathology of schizophrenia, the transcript structure of GAD1 in the human brain has not been fully characterized...
May 9, 2017: Molecular Psychiatry
https://www.readbyqxmd.com/read/28394147/a-lower-ratio-of-omega-6-to-omega-3-fatty-acids-predicts-better-hippocampus-dependent-spatial-memory-and-cognitive-status-in-older-adults
#14
Nadia D Andruchow, Kyoko Konishi, Bryna Shatenstein, Véronique D Bohbot
OBJECTIVE: Evidence from several cross-sectional studies indicates that an increase in omega-6 to omega-3 fatty acids (FAs) may negatively affect cognition in old age. The hippocampus is among the first neural structures affected by age and atrophy in this brain region is associated with cognitive decline. Therefore, we hypothesized that a lower omega-6:3 FA ratio would predict better hippocampus-dependent spatial memory, and a higher general cognitive status. METHOD: Fifty-two healthy older adults completed a Food Frequency Questionnaire, the Montreal Cognitive Assessment test (MoCA; a test of global cognition) and virtual navigation tasks that assess navigational strategies and spatial memory...
April 10, 2017: Neuropsychology
https://www.readbyqxmd.com/read/28321961/aging-affects-spatial-reconstruction-more-than-spatial-pattern-separation-performance-even-after-extended-practice
#15
Rachel Clark, Asli C Tahan, Patrick D Watson, Joan Severson, Neal J Cohen, Michelle Voss
Although the hippocampus experiences age-related anatomical and functional deterioration, the effects of aging vary across hippocampal-dependent cognitive processes. In particular, whether or not the hippocampus is known to be required for a spatial memory process is not an accurate predictor on its own of whether aging will affect performance. Therefore, the primary objective of this study was to compare the effects of healthy aging on a test of spatial pattern separation and a test of spatial relational processing, which are two aspects of spatial memory that uniquely emphasize the use of multiple hippocampal-dependent processes...
March 21, 2017: Hippocampus
https://www.readbyqxmd.com/read/28260633/plasticity-of-hippocampal-memories-in-humans
#16
REVIEW
Aidan J Horner, Christian F Doeller
The human hippocampus is a brain region that supports episodic and spatial memory. Recent experiments have drawn on animal research and computational modelling to reveal how the unique computations and representations of the hippocampus support episodic and spatial memory. Invasive electrophysiological recordings and non-invasive functional brain imaging have provided evidence for the rapid formation of hippocampal representations, as well as the ability of the hippocampus to both pattern-separate and pattern-complete input from the neocortex...
March 2, 2017: Current Opinion in Neurobiology
https://www.readbyqxmd.com/read/28256199/cross-cultural-differences-in-the-neural-correlates-of-specific-and-general-recognition
#17
Laura E Paige, John C Ksander, Hunter A Johndro, Angela H Gutchess
Research suggests that culture influences how people perceive the world, which extends to memory specificity, or how much perceptual detail is remembered. The present study investigated cross-cultural differences (Americans vs East Asians) at the time of encoding in the neural correlates of specific versus general memory formation. Participants encoded photos of everyday items in the scanner and 48 h later completed a surprise recognition test. The recognition test consisted of same (i.e., previously seen in scanner), similar (i...
February 3, 2017: Cortex; a Journal Devoted to the Study of the Nervous System and Behavior
https://www.readbyqxmd.com/read/28213155/high-frequency-stimulation-of-afferent-fibers-generates-asynchronous-firing-in-the-downstream-neurons-in-hippocampus-through-partial-block-of-axonal-conduction
#18
Zhouyan Feng, Zhaoxiang Wang, Zheshan Guo, Wenjie Zhou, Ziyan Cai, Dominique M Durand
Deep brain stimulation (DBS) is effective for treating neurological disorders in clinic. However, the therapeutic mechanisms of high-frequency stimulation (HFS) of DBS have not yet been elucidated. Previous studies have suggested that HFS-induced changes in axon conduction could have important contributions to the DBS effects and desiderate further studies. To investigate the effects of prolonged HFS of afferent axons on the firing of downstream neurons, HFS trains of 100 and 200Hz were applied on the Schaffer collaterals of the hippocampal CA1 region in anaesthetized rats...
April 15, 2017: Brain Research
https://www.readbyqxmd.com/read/28188304/-18-f-fdg-pet-patterns-of-surgical-success-and-failure-in-mesial-temporal-lobe-epilepsy
#19
Francine Chassoux, Eric Artiges, Franck Semah, Agathe Laurent, Elisabeth Landré, Baris Turak, Philippe Gervais, Badia-Ourkia Helal, Bertrand Devaux
OBJECTIVE: To search for [(18)F]-fluorodeoxyglucose (FDG)-PET patterns predictive of long-term prognosis in surgery for drug-resistant mesial temporal lobe epilepsy (MTLE) due to hippocampal sclerosis (HS). METHODS: We analyzed metabolic data with [(18)F]-FDG-PET in 97 patients with MTLE (53 female participants; age range 15-56 years) with unilateral HS (50 left) and compared the metabolic patterns, electroclinical features, and structural atrophy on MRI in patients with the best outcome after anteromesial temporal resection (Engel class IA, completely seizure-free) to those with a non-IA outcome, including suboptimal outcome and failure...
March 14, 2017: Neurology
https://www.readbyqxmd.com/read/28131561/-fragile-x-syndrome-and-white-matter-abnormalities-case-study-of-two-brothers
#20
E Wallach, E Bieth, A Sevely, C Cances
Fragile X syndrome is the most usual cause of hereditary intellectual deficiency. Typical symptoms combine intellectual deficiency, social anxiety, intense emotional vigilance, and a characteristic facial dysmorphy. This is subsequent to a complete mutation of the FMR1 gene, considering a semidominant transmission linked to the unstable X. The expansion of the CGG triplet greater than 200 units combined with a high methylation pattern lead to a transcriptional silence of the FMR1 gene, and the protein product, the FMRP, is not synthesized...
January 25, 2017: Archives de Pédiatrie: Organe Officiel de la Sociéte Française de Pédiatrie
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