We analyze the emergent regimes and the stimulus-response relationship of a population of noisy map neurons by means of a mean-field model, derived within the framework of cumulant approach complemented by the Gaussian closure hypothesis. It is demonstrated that the mean-field model can qualitatively account for stability and bifurcations of the exact system, capturing all the generic forms of collective behavior, including macroscopic excitability, subthreshold oscillations, periodic or chaotic spiking, and chaotic bursting dynamics. Apart from qualitative analogies, we find a substantial quantitative agreement between the exact and the approximate system, as reflected in matching of the parameter domains admitting the different dynamical regimes, as well as the characteristic properties of the associated time series. The effective model is further shown to reproduce with sufficient accuracy the phase response curves of the exact system and the assembly's response to external stimulation of finite amplitude and duration.
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http://dx.doi.org/10.1103/PhysRevE.96.012226 | DOI Listing |
Alzheimers Dement
December 2024
University of Michigan, Ann Arbor, MI, USA.
Background: Inhibitory interneurons normally regulate neural networks underlying memory and cognition, but are disrupted in Alzheimer's disease. Proper interneuron activity reduces amyloid-beta, whereas hyperexcitability elevates amyloid levels. Still, the underlying pathologic processes mediating interneuron dysfunction remain unknown.
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December 2024
University of Colorado, Anschutz Medical Campus, Aurora, CO, USA.
Motor proteins play a key role in neuronal functions and morphology that are important for learning and memory. We have previously reported that increased expression KIF11/Kinesin-5 overrides Aß-mediated effects on dendritic spine density and long-term potentiation in a mouse model of Alzheimer's disease (AD), effectively maintaining cognitive function in the face of Aß pathology. Here, we evaluated the association of key AD phenotypes with mRNA expression levels of a select set of Dynein motor proteins METHOD: We utilized measurements of gene expression, AD neuropathology burden, and cognition provided by the ROS/MAP study to determine whether an association exists between AD phenotypes and expression of genes for cytoplasmic and axonemal dynein heavy chains.
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December 2024
Physiopathology in Aging Laboratory (LIM-22), University of São Paulo Medical School, São Paulo, São Paulo, Brazil.
Background: Excessive daytime sleepiness is a common and early symptom of Alzheimer's disease (AD). The subcortical wake-promoting neurons in the lateral hypothalamic area, tuberomammillary nucleus (TMN), and locus coeruleus synchronize to maintain wakefulness/arousal. Although significant neuronal decline occurs in wake-promoting regions, the TMN histaminergic neurons remain relatively more intact than orexinergic and nor-adrenergic neurons.
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December 2024
Cornell University, Ithaca, NY, USA.
Background: Spatial disorientation is an early symptom of Alzheimer's disease (AD). The hippocampus creates a cognitive map, wherein cells form firing fields in specific locations within an environment, termed place cells. Critically, place cells remain stable across visits to an environment, but change their firing rate or field location in a different environment.
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December 2024
Department of Pathology and Laboratory Medicine, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA, USA.
Background: Recent studies suggest genome-wide-association-studies (GWAS) loci confer their effects on microglia in late-onset Alzheimer's disease (LOAD) brains. Relatively fewer studies have investigated the effects of other genome-wide significant loci (p<5e) using human neurons.
Method: GWAS itself cannot directly identify causal variant-(effector)gene-pairs as GWAS only reports the sentinel variant at a given locus.
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