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Entorhinal cortex

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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/28811255/cortical-layers-cyto-myelo-receptor-and-synaptic-architecture-in-human-cortical-areas
#2
REVIEW
Nicola Palomero-Gallagher, Karl Zilles
Cortical layers have classically been identified by their distinctive and prevailing cell types and sizes, as well as the packing densities of cell bodies or myelinated fibers. The densities of multiple receptors for classical neurotransmitters also vary across the depth of the cortical ribbon, and thus determine the neurochemical properties of cyto- and myeloarchitectonic layers. However, a systematic comparison of the correlations between these histologically definable layers and the laminar distribution of transmitter receptors is currently lacking...
August 12, 2017: NeuroImage
https://www.readbyqxmd.com/read/28807787/trigeminal-nerve-stimulation-induces-fos-immunoreactivity-in-selected-brain-regions-increases-hippocampal-cell-proliferation-and-reduces-seizure-severity-in-rats
#3
Beniamina Mercante, Paolo Enrico, Gabriele Floris, Marina Quartu, Marianna Boi, Maria Pina Serra, Paolo Follesa, Franca Deriu
Sites and mechanisms by which trigeminal nerve stimulation (TNS) exerts beneficial effects on symptoms of drug-resistant epilepsy and depression are still unknown. Effects of short-term TNS on brain regions involved in the physiopathology of these disorders were investigated in this study. Forty male rats were assigned to 3 groups: TNS (undergoing electrical stimulation of the left infraorbitary nerve via surgically implanted cuff electrodes); Sham (undergoing surgical procedure but without a stimulation); Naïve rats...
August 11, 2017: Neuroscience
https://www.readbyqxmd.com/read/28807028/connectivity-not-region-intrinsic-properties-predicts-regional-vulnerability-to-progressive-tau-pathology-in-mouse-models-of-disease
#4
Chris Mezias, Eve LoCastro, Chuying Xia, Ashish Raj
Spatiotemporal tau pathology progression is regarded as highly stereotyped within each type of degenerative condition. For instance, AD has a progression of tau pathology consistently beginning in the entorhinal cortex, the locus coeruleus, and other nearby noradrenergic brainstem nuclei, before spreading to the rest of the limbic system as well as the cingulate and retrosplenial cortices. Proposed explanations for the consistent spatial patterns of tau pathology progression, as well as for why certain regions are selectively vulnerable to exhibiting pathology over the course of disease generally focus on transsynaptic spread proceeding via the brain's anatomic connectivity network in a cell-independent manner or on cell-intrinsic properties that might render some cell populations or regions uniquely vulnerable...
August 14, 2017: Acta Neuropathologica Communications
https://www.readbyqxmd.com/read/28800330/pet-tau-and-amyloid-%C3%AE-burden-in-mild-alzheimer-s-disease-divergent-relationship-with-age-cognition-and-cerebrospinal-fluid-biomarkers
#5
Ivan Koychev, Roger N Gunn, Azadeh Firouzian, Jennifer Lawson, Giovanna Zamboni, Basil Ridha, Barbara J Sahakian, James B Rowe, Alan Thomas, Lynn Rochester, Dominic Ffytche, Robert Howard, Henrik Zetterberg, Clare MacKay, Simon Lovestone
BACKGROUND: Combining PET amyloid-β (Aβ) and tau imaging may be critical for tracking disease progression in Alzheimer's disease (AD). OBJECTIVE: We sought to characterize the relationship between Aβ and tau ligands as well as with other measures of pathology. METHODS: We conducted a multi-center observational study in early AD (MMSE >20) participants aged 50 to 85 y. The schedule included cognitive assessments (ADAS-Cog) and CSF measurement of Aβ and tau at baseline and 6 months; PET-CT imaging with Aβ ([18F]AV45) and tau ([18F]AV1451) ligands at baseline...
August 8, 2017: Journal of Alzheimer's Disease: JAD
https://www.readbyqxmd.com/read/28790897/regional-specific-evidence-for-memory-load-dependent-activity-in-the-dorsal-subiculum-and-the-lateral-entorhinal-cortex
#6
Shih-Pi Ku, Nozomu H Nakamura, Nicolas Maingret, Liv Mahnke, Motoharu Yoshida, Magdalena M Sauvage
The subiculum and the lateral entorhinal cortex (LEC) are the main output areas of the hippocampus which contribute to spatial and non-spatial memory. The proximal part of the subiculum (bordering CA1) receives heavy projections from the perirhinal cortex and the distal part of CA1 (bordering the subiculum), both known for their ties to object recognition memory. However, the extent to which the proximal subiculum contributes to non-spatial memory is still unclear. Comparatively, the involvement of the LEC in non-spatial information processing is quite well known...
2017: Frontiers in Systems Neuroscience
https://www.readbyqxmd.com/read/28777606/hippocampal-spike-timing-correlations-lead-to-hexagonal-grid-fields
#7
Mauro M Monsalve-Mercado, Christian Leibold
Space is represented in the mammalian brain by the activity of hippocampal place cells, as well as in their spike-timing correlations. Here, we propose a theory for how this temporal code is transformed to spatial firing rate patterns via spike-timing-dependent synaptic plasticity. The resulting dynamics of synaptic weights resembles well-known pattern formation models in which a lateral inhibition mechanism gives rise to a Turing instability. We identify parameter regimes in which hexagonal firing patterns develop as they have been found in medial entorhinal cortex...
July 21, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28776308/susceptibility-to-soman-toxicity-and-efficacy-of-ly293558-against-soman-induced-seizures-and-neuropathology-in-10-month-old-male-rats
#8
James P Apland, Vassiliki Aroniadou-Anderjaska, Taiza H Figueiredo, Eric M Prager, Cara H Olsen, Maria F M Braga
Acute nerve agent exposure causes prolonged status epilepticus (SE), leading to death or long-term brain damage. We have previously demonstrated that LY293558, an AMPA/GluK1 kainate receptor antagonist, terminates SE induced by the nerve agent soman and protects from long-term brain damage, in immature rats and young-adult rats, even if administered with a relatively long latency from the time of exposure. However, susceptibility to the lethal consequences of SE increases with age, and mortality by SE induced by soman is substantially greater in older animals...
August 3, 2017: Neurotoxicity Research
https://www.readbyqxmd.com/read/28772124/proximodistal-heterogeneity-of-hippocampal-ca3-pyramidal-neuron-intrinsic-properties-connectivity-and-reactivation-during-memory-recall
#9
Qian Sun, Alaba Sotayo, Alejandro S Cazzulino, Anna M Snyder, Christine A Denny, Steven A Siegelbaum
The hippocampal CA3 region is classically viewed as a homogeneous autoassociative network critical for associative memory and pattern completion. However, recent evidence has demonstrated a striking heterogeneity along the transverse, or proximodistal, axis of CA3 in spatial encoding and memory. Here we report the presence of striking proximodistal gradients in intrinsic membrane properties and synaptic connectivity for dorsal CA3. A decreasing gradient of mossy fiber synaptic strength along the proximodistal axis is mirrored by an increasing gradient of direct synaptic excitation from entorhinal cortex...
August 2, 2017: Neuron
https://www.readbyqxmd.com/read/28771717/organizational-connectivity-among-the-ca1-subiculum-presubiculum-and-entorhinal-cortex-in-the-rabbit
#10
Yoshiko Honda, Hideshi Shibata
The laminar and topographical organization of connections between the hippocampal formation and parahippocampal regions was investigated in the rabbit following in vivo injection of cholera toxin B subunit as a retro- and anterograde tracer and biotinylated dextran amine as an anterograde tracer. We confirmed several connectional features different from those of the rat, i.e., the rabbit presubiculum received abundant afferents from CA1 and had many reciprocal connections with the entorhinal cortex. On the other hand, we identified many similarities with the rat: both the CA1 and subicular afferents that originated from the entorhinal cortex were abundant; moreover, the presubiculum received many inputs from the subiculum and sent massive projections to the entorhinal cortex...
August 2, 2017: Journal of Comparative Neurology
https://www.readbyqxmd.com/read/28769779/size-matters-how-scaling-affects-the-interaction-between-grid-and-border-cells
#11
Diogo Santos-Pata, Riccardo Zucca, Sock C Low, Paul F M J Verschure
Many hippocampal cell types are characterized by a progressive increase in scale along the dorsal-to-ventral axis, such as in the cases of head-direction, grid and place cells. Also located in the medial entorhinal cortex (MEC), border cells would be expected to benefit from such scale modulations. However, this phenomenon has not been experimentally observed. Grid cells in the MEC of mammals integrate velocity related signals to map the environment with characteristic hexagonal tessellation patterns. Due to the noisy nature of these input signals, path integration processes tend to accumulate errors as animals explore the environment, leading to a loss of grid-like activity...
2017: Frontiers in Computational Neuroscience
https://www.readbyqxmd.com/read/28768062/self-organization-of-modular-activity-of-grid-cells
#12
Eugenio Urdapilleta, Bailu Si, Alessandro Treves
A unique topographical representation of space is found in the concerted activity of grid cells in the rodent medial entorhinal cortex. Many among the principal cells in this region exhibit a hexagonal firing pattern, in which each cell expresses its own set of place fields (spatial phases) at the vertices of a triangular grid, the spacing and orientation of which are typically shared with neighboring cells. Grid spacing, in particular, has been found to increase along the dorso-ventral axis of the entorhinal cortex but in discrete steps, i...
August 2, 2017: Hippocampus
https://www.readbyqxmd.com/read/28766965/map2-ihc-detection-a-marker-of-antigenicity-in-cns-tissues
#13
M R D'Andrea, R J Howanski, C F Saller
Immunohistochemistry (IHC) is used to detect antibody-specific antigens in tissues; the results depend on the ability of the primary antibodies to bind to their antigens. Therefore, results depend on the quality of preservation of the specimen. Many investigators have overcome the deleterious effects of over-fixation on the binding of primary antibodies to specimen antigens using IHC, but if the specimen is under-fixed or fixation is delayed, false negative results could be obtained despite certified laboratory practices...
August 2, 2017: Biotechnic & Histochemistry: Official Publication of the Biological Stain Commission
https://www.readbyqxmd.com/read/28764771/sensitivity-of-restriction-spectrum-imaging-to-memory-and-neuropathology-in-alzheimer-s-disease
#14
Emilie T Reas, Donald J Hagler, Nathan S White, Joshua M Kuperman, Hauke Bartsch, Karalani Cross, Richard Q Loi, Akshara R Balachandra, M J Meloy, Christina E Wierenga, Douglas Galasko, James B Brewer, Anders M Dale, Linda K McEvoy
BACKGROUND: Diffusion imaging has demonstrated sensitivity to structural brain changes in Alzheimer's disease (AD). However, there remains a need for a more complete characterization of microstructural alterations occurring at the earliest disease stages, and how these changes relate to underlying neuropathology. This study evaluated the sensitivity of restriction spectrum imaging (RSI), an advanced diffusion magnetic resonance imaging (MRI) technique, to microstructural brain changes in mild cognitive impairment (MCI) and AD...
August 2, 2017: Alzheimer's Research & Therapy
https://www.readbyqxmd.com/read/28764767/monoamine-oxidase-b-is-elevated-in-alzheimer-disease-neurons-is-associated-with-%C3%AE-secretase-and-regulates-neuronal-amyloid-%C3%AE-peptide-levels
#15
Sophia Schedin-Weiss, Mitsuhiro Inoue, Lenka Hromadkova, Yasuhiro Teranishi, Natsuko Goto Yamamoto, Birgitta Wiehager, Nenad Bogdanovic, Bengt Winblad, Anna Sandebring-Matton, Susanne Frykman, Lars O Tjernberg
BACKGROUND: Increased levels of the pathogenic amyloid β-peptide (Aβ), released from its precursor by the transmembrane protease γ-secretase, are found in Alzheimer disease (AD) brains. Interestingly, monoamine oxidase B (MAO-B) activity is also increased in AD brain, but its role in AD pathogenesis is not known. Recent neuroimaging studies have shown that the increased MAO-B expression in AD brain starts several years before the onset of the disease. Here, we show a potential connection between MAO-B, γ-secretase and Aβ in neurons...
August 1, 2017: Alzheimer's Research & Therapy
https://www.readbyqxmd.com/read/28761928/familiarity-deficits-in-cognitively-normal-aging-individuals-with-apoe-%C3%AE%C2%B54-a-follow-up-investigation-of-medial-temporal-lobe-structural-correlates
#16
Dorothee Schoemaker, Judes Poirier, D Louis Collins, Serge Gauthier, Jens C Pruessner
INTRODUCTION: The apolipoprotein E ε4 (APOE ε4) allele is a well-documented risk factor for Alzheimer's disease (AD). Accordingly, aging individuals carrying one or more ε4 alleles are at considerably greater risk of developing AD over time. In an effort to characterize early cognitive manifestations of AD, we previously outlined selective deficits in familiarity-based recognition in otherwise asymptomatic carriers of the APOE ε4 allele (Schoemaker et al., 2016). In this follow-up report, we aimed to explore the neural correlates of this selective cognitive impairment...
2017: Alzheimer's & Dementia: Diagnosis, Assessment & Disease Monitoring
https://www.readbyqxmd.com/read/28760699/modulation-of-the-storage-of-social-recognition-memory-by-neurotransmitter-systems-in-the-insular-cortex
#17
Lorena E S Cavalcante, Carolina G Zinn, Scheila D Schmidt, Bruna F Saenger, Flávia F Ferreira, Cristiane R G Furini, Jociane C Myskiw, Ivan Izquierdo
The insular cortex (IC) receives projections from prefrontal, entorhinal and cingulate cortex, olfactory bulb and basal nuclei and has reciprocal connections with the amygdala and entorhinal cortex. These connections suggest a possible involvement in memory processes; this has been borne out by data on several behaviors. Social recognition memory (SRM) is essential to form social groups and to establish hierarchies and social and affective ties. Despite its importance, knowledge about the brain structures and the neurotransmitter mechanisms involved in its processing is still scarce...
July 29, 2017: Behavioural Brain Research
https://www.readbyqxmd.com/read/28757194/time-resolved-phase-amplitude-coupling-in-neural-oscillations
#18
Soheila Samiee, Sylvain Baillet
Cross-frequency coupling between neural oscillations is a phenomenon observed across spatial scales in a wide range of preparations, including human non-invasive electrophysiology. Although the functional role and mechanisms involved are not entirely understood, the concept of interdependent neural oscillations drives an active field of research to comprehend the ubiquitous polyrhythmic activity of the brain, beyond empirical observations. Phase-amplitude coupling, a particular form of cross-frequency coupling between bursts of high-frequency oscillations and the phase of lower frequency rhythms, has recently received considerable attention...
July 27, 2017: NeuroImage
https://www.readbyqxmd.com/read/28756950/grid-cells-encode-local-positional-information
#19
Revekka Ismakov, Omri Barak, Kate Jeffery, Dori Derdikman
The brain has an extraordinary ability to create an internal spatial map of the external world [1]. This map-like representation of environmental surroundings is encoded through specific types of neurons, located within the hippocampus and entorhinal cortex, which exhibit spatially tuned firing patterns [2, 3]. In addition to encoding space, these neurons are believed to be related to contextual information and memory [4-7]. One class of such cells is the grid cells, which are located within the entorhinal cortex, presubiculum, and parasubiculum [3, 8]...
August 7, 2017: Current Biology: CB
https://www.readbyqxmd.com/read/28756238/av-1451-pet-imaging-of-tau-pathology-in-preclinical-alzheimer-disease-defining-a-summary-measure
#20
Shruti Mishra, Brian A Gordon, Yi Su, Jon Christensen, Karl Friedrichsen, Kelley Jackson, Russ Hornbeck, David A Balota, Nigel J Cairns, John C Morris, Beau M Ances, Tammie L S Benzinger
Utilizing [18F]-AV-1451 tau positron emission tomography (PET) as an Alzheimer disease (AD) biomarker will require identification of brain regions that are most important in detecting elevated tau pathology in preclinical AD. Here, we utilized an unsupervised learning, data-driven approach to identify brain regions whose tau PET is most informative in discriminating low and high levels of [18F]-AV-1451 binding. 84 cognitively normal participants who had undergone AV-1451 PET imaging were used in a sparse k-means clustering with resampling analysis to identify the regions most informative in dividing a cognitively normal population into high tau and low tau groups...
July 26, 2017: NeuroImage
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