Search results for "Entorhinal Cortex"
showing 10 items of 21 documents
Synaptic Phospholipid Signaling Modulates Axon Outgrowth via Glutamate-dependent Ca2+-mediated Molecular Pathways.
2015
Abstract Altered synaptic bioactive lipid signaling has been recently shown to augment neuronal excitation in the hippocampus of adult animals by activation of presynaptic LPA2-receptors leading to increased presynaptic glutamate release. Here, we show that this results in higher postsynaptic Ca2+ levels and in premature onset of spontaneous neuronal activity in the developing entorhinal cortex. Interestingly, increased synchronized neuronal activity led to reduced axon growth velocity of entorhinal neurons which project via the perforant path to the hippocampus. This was due to Ca2+-dependent molecular signaling to the axon affecting stabilization of the actin cytoskeleton. The spontaneous…
Neuronal Excitability And Spontaneous Synaptic Transmission In The Entorhinal Cortex Of Bdnf Heterozygous Mice
2018
Abstract Brain Derived Neurotropic Factor (BDNF) is a neutrophic factor that is required for the normal neuronal development and function. BDNF is involved in regulation of synapses as well as neuronal excitability. Entorhinal Cortex (EC) is a key brain area involved in many physiological and pathological processes. In this study we investigated the effects of chronically reduced BDNF levels on layer 3 pyramidal neurons of EC. We aimed to assess the effects of reduced levels of BDNF on firing properties, spontaneous synaptic currents and excitation/inhibition balance from acute brain slices. Patch clamp recordings were obtained from pyramidal neurons of Entorhinal Cortex Layer 3. Findings o…
Impairment of Everyday Spatial Navigation Abilities in Mild Cognitive Impairment Is Weakly Associated with Reduced Grey Matter Volume in the Medial P…
2020
Alzheimer’s Disease Neuroimaging Initiative.
Hippocampal electrical stimulation disrupts associative learning when targeted at dentate spikes
2017
KEY POINTS Dentate spikes are fast fluctuations of hilar local-field potentials that take place during rest and are thought to reflect input arriving from the entorhinal cortex to the hippocampus. During dentate spikes, neuronal firing in hippocampal input (dentate gyrus) and output (CA1/CA3) regions is uncoupled. To date, the behavioural significance of dentate spikes is unknown. Here, we provide evidence that disrupting the dentate spike-related uncoupling of the dentate gyrus and the CA1/CA3 subregions for 1 h after training retards associative learning. We suggest dentate spikes play a significant role in memory consolidation. ABSTRACT Hippocampal electrophysiological oscillations, name…
Complexity analysis of cortical surface detects changes in future Alzheimer's disease converters
2017
Alzheimer's disease (AD) is a neurological disorder that creates neurodegenerative changes at several structural and functional levels in human brain tissue. The fractal dimension (FD) is a quantitative parameter that characterizes the morphometric variability of the human brain. In this study, we investigate spherical harmonic-based FD (SHFD), thickness, and local gyrification index (LGI) to assess whether they identify cortical surface abnormalities toward the conversion to AD. We study 33 AD patients, 122 mild cognitive impairment (MCI) patients (50 MCI converters and 29 MCI nonconverters), and 32 healthy controls (HC). SHFD, thickness, and LGI methodology allowed us to perform not only …
Quantitative investigations on the human entorhinal area: left-right asymmetry and age-related changes
1994
The total nerve cell numbers in the right and in the left human entorhinal areas have been calculated by volume estimations with the Cavalieri principle and by cell density determinations with the optical disector. Thick gallocyanin-stained serial frozen sections through the parahippocampal gyrus of 22 human subjects (10 female, 12 male) ranging from 18 to 86 years were analysed. The laminar composition of gallocyanin (Nissl)-stained sections could easily be compared with Braak's (1972, 1980) pigmentoarchitectonic study, and Braak's nomenclature of the entorhinal laminas was adopted. Cell-sparse laminae dissecantes can more clearly be distinguished in Nissl than in aldehydefuchsin preparati…
Subregional Pathology of the Amygdala Complex and Entorhinal Region in Surgical Specimens From Patients With Pharmacoresistant Temporal Lobe Epilepsy
2000
The hippocampus, amygdala complex, and entorhinal region represent anatomically linked limbic structures of the mesiotemporal lobe. Chronic seizures and mnestic deficits in patients with pharmacoresistant mesial temporal lobe epilepsy (TLE) appear to correlate with distinct patterns of histopathological alterations in these areas. The complex anatomical organization of the amygdala and entorhinal region, however, render a detailed neuropathological evaluation of surgical specimens difficult. In this study, we present a combined cytoarchitectonical, pigmentarchitectonical, myelinarchitectonical, and immunohistochemical reconstruction of the amygdala, entorhinal region, and hippocampus from s…
Neurons of the dentate molecular layer in the rabbit hippocampus.
2012
The molecular layer of the dentate gyrus appears as the main entrance gate for information into the hippocampus, i.e., where the perforant path axons from the entorhinal cortex synapse onto the spines and dendrites of granule cells. A few dispersed neuronal somata appear intermingled in between and probably control the flow of information in this area. In rabbits, the number of neurons in the molecular layer increases in the first week of postnatal life and then stabilizes to appear permanent and heterogeneous over the individuals' life span, including old animals. By means of Golgi impregnations, NADPH histochemistry, immunocytochemical stainings and intracellular labelings (lucifer yellow…
An update to Hippocampome.org by integrating single-cell phenotypes with circuit function in vivo.
2021
Understanding brain operation demands linking basic behavioral traits to cell-type specific dynamics of different brain-wide subcircuits. This requires a system to classify the basic operational modes of neurons and circuits. Single-cell phenotyping of firing behavior during ongoing oscillations in vivo has provided a large body of evidence on entorhinal–hippocampal function, but data are dispersed and diverse. Here, we mined literature to search for information regarding the phase-timing dynamics of over 100 hippocampal/entorhinal neuron types defined in Hippocampome.org. We identified missing and unresolved pieces of knowledge (e.g., the preferred theta phase for a specific neuron type) a…
Episodic memories: how do the hippocampus and the entorhinal ring attractors cooperate to create them?
2020
AbstractThe brain is capable of registering a constellation of events, encountered only once, as an episodic memory that can last for a lifetime. As evidenced by the clinical case of the patient HM, memories preserving their episodic nature still depend on the hippocampal formation, several years after being created, while semantic memories are thought to reside in neocortical areas. The neurobiological substrate of one-time learning and life-long storing in the brain, that must exist at the cellular and circuit level, is still undiscovered. The breakthrough is delayed by the fact that studies jointly investigating the rodent hippocampus and entorhinal cortex are mostly targeted at understa…