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CA2 hippocampus

Sarah M Szymkowicz, Molly E McLaren, Andrew O'Shea, Adam J Woods, Stephen D Anton, Vonetta M Dotson
AIM: Major depression is associated with hippocampal volume changes, especially in late-life depression. These changes usually consist of volume reductions, but depression-related increases in hippocampal volume have also been reported. Subfield analysis has identified structural changes primarily in the cornu ammonis (CA) 1, CA2-3 and subiculum of the hippocampus in individuals with major depression; however, it is unclear whether lower levels of depressive symptoms are also associated volume reduction, or if depressive symptoms interact with age to impact hippocampal subfields...
October 2, 2016: Geriatrics & Gerontology International
Saurabh Kumar Jha, Niraj Kumar Jha, Dhiraj Kumar, Renu Sharma, Abhishek Shrivastava, Rashmi K Ambasta, Pravir Kumar
The communication between neurons at synaptic junctions is an intriguing process that monitors the transmission of various electro-chemical signals in the central nervous system. Albeit any aberration in the mechanisms associated with transmission of these signals leads to loss of synaptic contacts in both the neocortex and hippocampus thereby causing insidious cognitive decline and memory dysfunction. Compelling evidence suggests that soluble amyloid-β (Aβ) and hyperphosphorylated tau serve as toxins in the dysfunction of synaptic plasticity and aberrant neurotransmitter (NT) release at synapses consequently causing a cognitive decline in Alzheimer's disease (AD)...
September 23, 2016: Journal of Alzheimer's Disease: JAD
Nobuyoshi Matsumoto, Kazuki Okamoto, Yuki Takagi, Yuji Ikegaya
The CA2 region is unique in the hippocampus; it receives direct synaptic innervations from several hypothalamic nuclei and expresses various receptors of neuromodulators, including adenosine, vasopressin, and oxytocin. Furthermore, the CA2 region may have distinct brain functions, such as the control of instinctive and social behaviors; however, little is known about the dynamics of the subthreshold membrane potentials of CA2 neurons in vivo. We conducted whole-cell current-clamp recordings from CA2 pyramidal cells in urethane-anesthetized mice and monitored the intrinsic fluctuations in their membrane potentials...
September 20, 2016: Hippocampus
Timothy B Meier, Melissa A Lancaster, Andrew R Mayer, T Kent Teague, Jonathan Savitz
There is a great need to identify potential long-term consequences of contact sport exposure and to identify molecular pathways that may be associated with these changes. We tested the hypothesis that football players with (Ath-mTBI) (n = 25) and without a concussion history (Ath) (n = 24) have altered resting state functional connectivity in regions with previously documented structural changes relative to healthy controls without football or concussion history (HC) (n = 27). As a secondary aim, we tested the hypothesis that group differences in functional connectivity are moderated by the relative ratio of neuroprotective to neurotoxic metabolites of the kynurenine pathway...
October 13, 2016: Journal of Neurotrauma
Azahara Oliva, Antonio Fernández-Ruiz, György Buzsáki, Antal Berényi
Sharp-wave ripples (SPW-Rs) in the hippocampus are implied in memory consolidation, as shown by observational and interventional experiments. However, the mechanism of their generation remains unclear. Using two-dimensional silicon probe arrays, we investigated the propagation of SPW-Rs across the hippocampal CA1, CA2, and CA3 subregions. Synchronous activation of CA2 ensembles preceded SPW-R-related population activity in CA3 and CA1 regions. Deep CA2 neurons gradually increased their activity prior to ripples and were suppressed during the population bursts of CA3-CA1 neurons (ramping cells)...
September 21, 2016: Neuron
Fikru Nigussie, Pei-San Huang, Kris Lukauskis, Bhupinder Bawa, Eid Moussa, Louise C Abbott
Tottering mutant mice carry a mutation in the pore-forming subunit (α1A) of CaV2.1 (P/Q-type) voltage-gated calcium ion (Ca(2+)) channels resulting in reduced neuronal Ca(2+) current density. We assessed male tottering mice for spatial learning using the Morris water maze. Tottering mice performed worse than wild type mice, suggesting abnormal hippocampal function. Because Ca(2+) influx via voltage-dependent Ca(2+) channels regulates neuronal survival and function, we assessed hippocampus volume and cell density using hematoxylin and eosin stained serial sections...
November 1, 2016: Brain Research
Daniel Reyes-Haro, Francisco Emmanuel Labrada-Moncada, Durairaj Ragu Varman, Janina Krüger, Teresa Morales, Ricardo Miledi, Ataúlfo Martínez-Torres
Anorexia nervosa is an eating disorder observed primarily in young women. The neurobiology of the disorder is unknown but recently magnetic resonance imaging showed a volume reduction of the hippocampus in anorexic patients. Dehydration-induced anorexia (DIA) is a murine model that mimics core features of this disorder, including severe weight loss due to voluntary reduction in food intake. The energy supply to the brain is mediated by astrocytes, but whether their density is compromised by anorexia is unknown...
2016: Neural Plasticity
Saeid Taheri, Jin Yu, Hong Zhu, Mark S Kindy
BACKGROUND: Cerebral ionic homeostasis impairment, especially Ca2+, has been observed in Alzheimer's disease (AD) and also with hypertension. Hypertension and AD both have been implicated in impaired cerebral autoregulation. However, the relationship between the ionic homeostasis impairment in AD and hypertension and cerebral blood flow (CBF) autoregulation is not clear. OBJECTIVE: To test the hypothesis that a high-salt diet regimen influences the accumulation of amyloid-β (Aβand CBF) and CBF, exacerbates cognitive decline, and increases the propensity to AD...
October 4, 2016: Journal of Alzheimer's Disease: JAD
Brendan G Santyr, Maged Goubran, Jonathan C Lau, Benjamin Y M Kwan, Fateme Salehi, Donald H Lee, Seyed M Mirsattari, Jorge G Burneo, David A Steven, Andrew G Parrent, Sandrine de Ribaupierre, Robert R Hammond, Terry M Peters, Ali R Khan
PURPOSE: To provide a more detailed investigation of hippocampal subfields using 7T magnetic resonance imaging (MRI) for the identification of hippocampal sclerosis in temporal lobe epilepsy (TLE). MATERIALS AND METHODS: Patients (n = 13) with drug-resistant TLE previously identified by conventional imaging as having hippocampal sclerosis (HS) or not (nine without HS, four HS) and 20 age-matched healthy controls were scanned and compared using a 7T MRI protocol...
August 26, 2016: Journal of Magnetic Resonance Imaging: JMRI
A P Türkmen, S Kaplan, A Aksoy, Bz Altunkaynak, Kk Yurt, E Elibol, C Çokluk, Me Onger
This study was aimed at evaluating the potential effects of acute subdural hematoma (ASDH) and diclofenac sodium (DS) therapy following ASDH on the rat hippocampus. Twenty-four male Sprague Dawley rats were used and divided into four groups. 0.1 ml of non-heparinized autologous blood from the tail vein of the animals in the non-treatment group (NTG) and treatment group (TG) was injected into the subdural space. The TG received intramuscular diclofenac sodium at a 15 mg/kg dose daily from the postoperative second hour to the seventh day after the operation...
2016: Folia Neuropathologica
Kenichi Tomiyama, Yasuaki Arakawa
This review explains the mechanisms of apoptosis related to the impacts of zinc deficiency and organotin exposure on the immune and central nervous systems. In the immune systems, both zinc deficiency and trialkyltin exposure lead to severe thymic atrophy and affect T-lymphocyte development through apoptosis of double positive stage pre-T-cells(CD4+/CD8+) in the cortex region. Their apoptosis are caused mainly through decrease in Bcl-2 expression, activation of ROS production/release, oxidative stress, mitochondrial cytochrome c release and activation of caspase cascade, with increases in glucocorticoids in zinc deficiency, without the involvement of glucocorticoid in organotin exposure In the central nervous system, both zinc deficiency and trialkyltin exposure reduce learning, memory and sensory functions through neuronal apoptosis caused by activation of ROS production/release, release of pro-apoptotic factors such as cytochrome c or apoptosis-inducing factor(AIF), with Fe excessive accumulation leading to ROS production and with depletion of hippocampus Zn (mossy fiber Zn) causing various Ca2+ channel disorder of synapse in the hippocampus, and with excessive accumulation of Ca through cAMP-dependent Ca(2+)-channel disorder by excessive PTH and cAMP excessive production in the olfactory systems such as olfactory epithelium and olfactory bulb...
July 2016: Nihon Rinsho. Japanese Journal of Clinical Medicine
Fei Zheng, Ming Zhang, Qi Ding, Ferzin Sethna, Lily Yan, Changjong Moon, Miyoung Yang, Hongbing Wang
Mental health and cognitive functions are influenced by both genetic and environmental factors. Although having active lifestyle with physical exercise improves learning and memory, how it interacts with the specific key molecular regulators of synaptic plasticity is largely unknown. Here, we examined the effects of voluntary running on long-term potentiation (LTP) and memory formation in mice lacking type 1 adenylyl cyclase (AC1), a neurospecific synaptic enzyme that contributes to Ca(2+)-stimulated cAMP production...
August 2016: Learning & Memory
Daniel M Salz, Zoran Tiganj, Srijesa Khasnabish, Annalyse Kohley, Daniel Sheehan, Marc W Howard, Howard Eichenbaum
UNLABELLED: Studies on time cells in the hippocampus have so far focused on area CA1 in animals performing memory tasks. Some studies have suggested that temporal processing within the hippocampus may be exclusive to CA1 and CA2, but not CA3, and may occur only under strong demands for memory. Here we examined the temporal and spatial coding properties of CA3 and CA1 neurons in rats performing a maze task that demanded working memory and a control task with no explicit working memory demand...
July 13, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Vivien Chevaleyre, Rebecca A Piskorowski
While the hippocampus has long been recognized as a brain structure specialized in mapping 'space' in rodents, human studies and now recent data from rodents have shown that its function extends well beyond spatial coding. Recently, an overlooked area of the hippocampus, CA2, has emerged as a critical region for social memory. This area is also uniquely altered during several pathologies such as schizophrenia and age-related dementia. Because of its singular connectivity, we propose that area CA2 resides at the interface between emotional brain activity and higher cognitive function...
August 2016: Trends in Molecular Medicine
Michael Willis, Maria Trieb, Irmgard Leitner, Georg Wietzorrek, Josef Marksteiner, Hans-Günther Knaus
SK2 (KCa2.2) channels are voltage-independent Ca(2+)-activated K(+) channels that regulate neuronal excitability in brain regions important for memory formation. In this study, we investigated the distribution and expression of SK2 channels in human brain by Western blot analysis and immunohistochemistry. Immunoblot analysis of human brain indicated expression of four distinct SK2 channel isoforms: the standard, the long and two short isoforms. Immunohistochemistry in paraffin-embedded post-mortem brain sections was performed in the hippocampal formation, amygdala and neocortex...
June 29, 2016: Brain Structure & Function
Kaoutsar Nasrallah, Rebecca Ann Piskorowski, Vivien Chevaleyre
Hippocampal area CA2 is emerging as a critical region for memory formation. Excitatory Scaffer collateral (SC) inputs from CA3 do not express activity-dependent plasticity at SC-CA2 synapses, and are governed by a large feed-forward inhibition that prevents them from engaging CA2 pyramidal neurons. However, long-term depression at inhibitory synapses evoked by stimulation of SC inputs highly increases the excitatory/inhibitory balance coming from CA3 and allows the recruitment of CA2 pyramidal neurons. In contrast, distal excitatory inputs in stratum lacunosum moleculare (SLM) can drive action potential firing in CA2 pyramidal neurons and also express a long-term potentiation...
June 25, 2016: Neurobiology of Learning and Memory
Shweta Hegde, Will R Capell, Baher A Ibrahim, Jennifer Klett, Neema S Patel, Alexander T Sougiannis, Michy P Kelly
The capacity to form long-lasting social memories is critical to our health and survival. cAMP signaling in the ventral hippocampal formation (VHIPP) appears to be required for social memory formation, but the phosphodiesterase (PDE) involved remains unknown. Previously, we showed that PDE11A, which degrades cAMP and cGMP, is preferentially expressed in CA1 and subiculum of the VHIPP. Here, we determine whether PDE11A is expressed in neurons where it could directly influence synaptic plasticity and whether expression is required for the consolidation and/or retrieval of social memories...
July 27, 2016: Neuropsychopharmacology: Official Publication of the American College of Neuropsychopharmacology
Reza Mahmoudi, Elham Enant, Hamdollah Delaviz, Parastou Rad, Amrollah Roozbehi, Mehrzad Jafari Barmak, Arsalan Azizi
INTRODUCTION: Prenatal stress has deleterious effects on the development of the brain and is associated with behavioral and psychosocial problems in childhood and adulthood. This study aimed to determine the protective effect of L-arginine on fetal brain under maternal stress. METHODS: Twenty pregnant Wistar rats (weighting 200-230 g) were randomly divided into 4 groups (n=5 for each group). The first nonstress and stress groups received 2 mL of normal saline and the other nonstress and stress two groups received L-arginine (200 mg/kg, IP) from their 5(th) to 20(th) days of pregnancy...
January 2016: Basic and Clinical Neuroscience
Kelly E Carstens, Mary L Phillips, Lucas Pozzo-Miller, Richard J Weinberg, Serena M Dudek
UNLABELLED: Long-term potentiation of excitatory synapses on pyramidal neurons in the stratum radiatum rarely occurs in hippocampal area CA2. Here, we present evidence that perineuronal nets (PNNs), a specialized extracellular matrix typically localized around inhibitory neurons, also surround mouse CA2 pyramidal neurons and envelop their excitatory synapses. CA2 pyramidal neurons express mRNA transcripts for the major PNN component aggrecan, identifying these neurons as a novel source for PNNs in the hippocampus...
June 8, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Ouafa Najyb, Sonia Do Carmo, Azadeh Alikashani, Eric Rassart
Excitotoxicity due to the excessive activation of glutamatergic receptors leads to neuronal dysfunction and death. Excitotoxicity has been implicated in the pathogenesis of a myriad of neurodegenerative diseases with distinct etiologies such as Alzheimer's and Parkinson's. Numerous studies link apolipoprotein D (apoD), a secreted glycoprotein highly expressed in the central nervous system (CNS), to maintain and protect neurons in various mouse models of acute stress and neurodegeneration. Here, we used a mouse model overexpressing human apoD in neurons (H-apoD Tg) to test the neuroprotective effects of apoD in the kainic acid (KA)-lesioned hippocampus...
June 7, 2016: Molecular Neurobiology
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