Search results for "hippocampal"
showing 10 items of 352 documents
Peripheral CB1 receptor blockade acts as a memory enhancer through an adrenergic-dependent mechanism
2021
Peripheral inputs to the brain continuously shape its function and can influence the formation of non-emotional memory, but the underlying mechanisms have not been fully understood. Cannabinoid type-1 receptors (CB1R), widely distributed in the organism, is a well-recognized player in memory performance, and its systemic modulation significantly influences memory function. By assessing non-emotional memory in mice, we have now found a relevant role of peripheral CB1R in the formation of persistent memory. Indeed, peripherally restricted CB1R antagonism by using AM6545 showed a mnemonic effect that was occluded in adrenalectomized mice, after peripheral adrenergic blockade, or when vagus ner…
Modelling the spatial and temporal constrains of the GABAergic influence on neuronal excitability
2021
GABA (γ-amino butyric acid) is an inhibitory neurotransmitter in the adult brain that can mediate depolarizing responses during development or after neuropathological insults. Under which conditions GABAergic membrane depolarizations are sufficient to impose excitatory effects is hard to predict, as shunting inhibition and GABAergic effects on spatiotemporal filtering of excitatory inputs must be considered. To evaluate at which reversal potential a net excitatory effect was imposed by GABA (EGABAThr), we performed a detailed in-silico study using simple neuronal topologies and distinct spatiotemporal relations between GABAergic and glutamatergic inputs. These simulations revealed for GABAe…
Postsynaptic NO/cGMP Increases NMDA Receptor Currents via Hyperpolarization-Activated Cyclic Nucleotide-Gated Channels in the Hippocampus
2013
The nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) signaling cascade participates in the modulation of synaptic transmission. The effects of NO are mediated by the NO-sensitive cGMP-forming guanylyl cyclases (NO-GCs), which exist in 2 isoforms with indistinguishable regulatory properties. The lack of long-term potentiation (LTP) in knock-out (KO) mice deficient in either one of the NO-GC isoforms indicates the contribution of both NO-GCs to LTP. Recently, we showed that the NO-GC1 isoform is located presynaptically in glutamatergic neurons and increases the glutamate release via hyperpolarization-activated cyclic nucleotide (HCN)-gated channels in the hippocampus. Electrophysiologi…
Manual segmentation qualification platform for the EADC-ADNI harmonized protocol for hippocampal segmentation project
2015
The use of hippocampal volumetry as a biomarker for Alzheimer's disease (AD) requires that tracers from different laboratories comply with the same segmentation method. Here we present a platform for training and qualifying new tracers to perform the manual segmentation of the hippocampus on magnetic resonance images (MRI) following the European Alzheimer's Disease Consortium and Alzheimer's Disease Neuroimaging Initiative (EADC-ADNI) Harmonized Protocol (HarP). Our objective was to demonstrate that the training process embedded in the platform leads to increased compliance and qualification with the HarP.Thirteen new tracers' segmentations were compared with benchmark images with respect t…
Abnormal accumulation of autophagic vesicles correlates with axonal and synaptic pathology in young Alzheimer's mice hippocampus
2012
Dystrophic neurites associated with amyloid plaques precede neuronal death and manifest early in Alzheimer's disease (AD). In this work we have characterized the plaque-associated neuritic pathology in the hippocampus of young (4- to 6-month-old) PS1(M146L)/APP(751SL) mice model, as the initial degenerative process underlying functional disturbance prior to neuronal loss. Neuritic plaques accounted for almost all fibrillar deposits and an axonal origin of the dystrophies was demonstrated. The early induction of autophagy pathology was evidenced by increased protein levels of the autophagosome marker LC3 that was localized in the axonal dystrophies, and by electron microscopic identification…
Transitory disappearance of microglia during the regeneration of the lizard medial cortex
1994
In normal lizards, microglial cells populate the medial cortex (a zone homologous to the hippocampal fascia dentata), with a preferential distribution along the border between the granular cell layer and the plexiform layers. Intraperitoneal injection of the neurotoxin 3-acetylpyridine (3AP) induces a selective lesion in the medial cortex with a rapid degeneration of the granular layer and its zinc-enriched axonal projection. Within 6-8 weeks, the granular layer is, however, re- populated by a new set of neurons generated in the subjacent ependyma and the cell debris is removed. The aim of this study was to determine to what extent microglia were involved in the scavenging processes during …
Comparative neuroscience of stimulant-induced memory dysfunction: role for neurogenesis in the adult hippocampus.
2010
The discovery that the addictive drugs impair neurogenesis in the adult hippocampus has prompted the elaboration of new biological hypotheses to explain addiction and drug-induced cognitive dysfunction. Considerable evidence now implicates the process of adult neurogenesis in at least some critical components of hippocampal-dependent memory function. In experimental models, psychomotor stimulant drugs produce alterations in the rate of birth, survival, maturation and functional integration of adult-born hippocampal neurons. Thus some of the deleterious consequences of drug abuse on memory could result from the neurotoxic actions of drugs on adult hippocampal neurogenesis. In this review, we…
Nigral control of hippocampal epilepsy: a dopaminergic hypothesis
1988
Effects of rewarding electrical stimulation of lateral hypothalamus on classical conditioning of the nictitating membrane response.
1997
1. Adult New Zealand albino rabbits were prepared with chronic hypothalamic stimulating electrodes and hippocampal recording electrodes. 2. Rabbits were restrained and classically conditioned by a tone CS and an airpuff US either followed or preceded by a hypothalamic stimulation (HS). Control rabbits were conditioned without the HS. 3. It was found that HS following the CS facilitated both behavioral and hippocampal responses, while HS preceding the CS inhibited them. 4. Enhanced hippocampal learning-related unit firing to the CS may represent an early indication of conditioning before the behavioral activity produces any observable change.