scholarly journals Homeostasis of intrinsic excitability in hippocampal neurones: dynamics and mechanism of the response to chronic depolarization

2010 ◽  
Vol 588 (1) ◽  
pp. 157-170 ◽  
Author(s):  
Timothy O’Leary ◽  
Mark C. W. van Rossum ◽  
David J. A. Wyllie
Keyword(s):  
Intrinsic Excitability ◽  
Chronic Depolarization

scholarly journals PKA-RIIβ autophosphorylation modulates PKA activity and seizure phenotypes in mice

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Jingliang Zhang ◽  
Chenyu Zhang ◽  
Xiaoling Chen ◽  
Bingwei Wang ◽  
Weining Ma ◽  
...  
Keyword(s):  
Therapeutic Target ◽  
Neurological Disorders ◽  
Neuronal Excitability ◽  
Granule Cells ◽  
Critical Role ◽  
Intrinsic Excitability ◽  
Seizure Susceptibility ◽  
Seizure Onset ◽  
Potential Therapeutic Target ◽  
Seizure Model

AbstractTemporal lobe epilepsy (TLE) is one of the most common and intractable neurological disorders in adults. Dysfunctional PKA signaling is causally linked to the TLE. However, the mechanism underlying PKA involves in epileptogenesis is still poorly understood. In the present study, we found the autophosphorylation level at serine 114 site (serine 112 site in mice) of PKA-RIIβ subunit was robustly decreased in the epileptic foci obtained from both surgical specimens of TLE patients and seizure model mice. The p-RIIβ level was negatively correlated with the activities of PKA. Notably, by using a P-site mutant that cannot be autophosphorylated and thus results in the released catalytic subunit to exert persistent phosphorylation, an increase in PKA activities through transduction with AAV-RIIβ-S112A in hippocampal DG granule cells decreased mIPSC frequency but not mEPSC, enhanced neuronal intrinsic excitability and seizure susceptibility. In contrast, a reduction of PKA activities by RIIβ knockout led to an increased mIPSC frequency, a reduction in neuronal excitability, and mice less prone to experimental seizure onset. Collectively, our data demonstrated that the autophosphorylation of RIIβ subunit plays a critical role in controlling neuronal and network excitabilities by regulating the activities of PKA, providing a potential therapeutic target for TLE.

scholarly journals Logarithmic distributions prove that intrinsic learning is Hebbian

F1000Research ◽  
2017 ◽  
Vol 6 ◽  
pp. 1222 ◽  
Author(s):  
Gabriele Scheler
Keyword(s):  
Adaptive Learning ◽  
Hebbian Learning ◽  
Neural Model ◽  
Intrinsic Excitability ◽  
Logarithmic Scale ◽  
Brain Areas ◽  
Lognormal Distributions ◽  
Learning Rules ◽  
Heavy Tailed ◽  
The Difference

In this paper, we present data for the lognormal distributions of spike rates, synaptic weights and intrinsic excitability (gain) for neurons in various brain areas, such as auditory or visual cortex, hippocampus, cerebellum, striatum, midbrain nuclei. We find a remarkable consistency of heavy-tailed, specifically lognormal, distributions for rates, weights and gains in all brain areas examined. The difference between strongly recurrent and feed-forward connectivity (cortex vs. striatum and cerebellum), neurotransmitter (GABA (striatum) or glutamate (cortex)) or the level of activation (low in cortex, high in Purkinje cells and midbrain nuclei) turns out to be irrelevant for this feature. Logarithmic scale distribution of weights and gains appears to be a general, functional property in all cases analyzed. We then created a generic neural model to investigate adaptive learning rules that create and maintain lognormal distributions. We conclusively demonstrate that not only weights, but also intrinsic gains, need to have strong Hebbian learning in order to produce and maintain the experimentally attested distributions. This provides a solution to the long-standing question about the type of plasticity exhibited by intrinsic excitability.

A Sparse Generative Model of V1 Simple Cells with Intrinsic Plasticity

2008 ◽  
Vol 20 (5) ◽  
pp. 1261-1284 ◽  
Author(s):  
Cornelius Weber ◽  
Jochen Triesch
Keyword(s):  
Dynamic Environment ◽  
Generative Model ◽  
Intrinsic Excitability ◽  
Natural Image ◽  
Tilt Aftereffect ◽  
Simple Cells ◽  
Feature Detectors ◽  
Edge Detectors ◽  
Intrinsic Plasticity ◽  
Slow Timescale

Current models for learning feature detectors work on two timescales: on a fast timescale, the internal neurons' activations adapt to the current stimulus; on a slow timescale, the weights adapt to the statistics of the set of stimuli. Here we explore the adaptation of a neuron's intrinsic excitability, termed intrinsic plasticity, which occurs on a separate timescale. Here, a neuron maintains homeostasis of an exponentially distributed firing rate in a dynamic environment. We exploit this in the context of a generative model to impose sparse coding. With natural image input, localized edge detectors emerge as models of V1 simple cells. An intermediate timescale for the intrinsic plasticity parameters allows modeling aftereffects. In the tilt aftereffect, after a viewer adapts to a grid of a certain orientation, grids of a nearby orientation will be perceived as tilted away from the adapted orientation. Our results show that adapting the neurons' gain-parameter but not the threshold-parameter accounts for this effect. It occurs because neurons coding for the adapting stimulus attenuate their gain, while others increase it. Despite its simplicity and low maintenance, the intrinsic plasticity model accounts for more experimental details than previous models without this mechanism.

Major Role For Tonic GABAA Conductances in Anesthetic Suppression of Intrinsic Neuronal Excitability

2004 ◽  
Vol 92 (3) ◽  
pp. 1658-1667 ◽  
Author(s):  
Mark C. Bieda ◽  
M. Bruce MacIver
Keyword(s):  
Synaptic Transmission ◽  
Neuronal Excitability ◽  
Brain Slices ◽  
Pyramidal Cells ◽  
Intrinsic Excitability ◽  
High Potassium ◽  
Ca1 Neurons ◽  
Adult Rat ◽  
Adult Rat Brain ◽  
Sites Of Action

Anesthetics appear to produce neurodepression by altering synaptic transmission and/or intrinsic neuronal excitability. Propofol, a widely used anesthetic, has proposed effects on many targets, ranging from sodium channels to GABAA inhibition. We examined effects of propofol on the intrinsic excitability of hippocampal CA1 neurons (primarily interneurons) recorded from adult rat brain slices. Propofol strongly depressed action potential production induced by DC injection, synaptic stimulation, or high-potassium solutions. Propofol-induced depression of intrinsic excitability was completely reversed by bicuculline and picrotoxin but was strychnine-insensitive, implicating GABAA but not glycine receptors. Propofol strongly enhanced inhibitory postsynaptic currents (IPSCs) and induced a tonic GABAA-mediated current. We pharmacologically differentiated tonic and phasic (synaptic) GABAA-mediated inhibition using the GABAA receptor antagonist SR95531 (gabazine). Gabazine (20 μM) completely blocked both evoked and spontaneous IPSCs but failed to block the propofol-induced depression of intrinsic excitability, implicating tonic, but not phasic, GABAA inhibition. Glutamatergic synaptic responses were not altered by propofol (≤30 μM). Similar results were found in both interneurons and pyramidal cells and with the chemically unrelated anesthetic thiopental. These results suggest that suppression of CA1 neuron intrinsic excitability, by these anesthetics, is largely due to activation of tonic GABAA conductances; although other sites of action may play important roles in affecting synaptic transmission, which also can produce strong neurodepression. We propose that for some anesthetics, suppression of intrinsic excitability, mediated by tonic GABAA conductances, operates in conjunction with effects on synaptic transmission, mediated by other mechanisms, to depress hippocampal function during anesthesia.

scholarly journals Relationship between individual neuron and network spontaneous activity in developing mouse cortex

2014 ◽  
Vol 112 (12) ◽  
pp. 3033-3045 ◽  
Author(s):  
Heather M. Barnett ◽  
Julijana Gjorgjieva ◽  
Keiko Weir ◽  
Cara Comfort ◽  
Adrienne L. Fairhall ◽  
...  
Keyword(s):  
Normal Development ◽  
Activity Patterns ◽  
Piriform Cortex ◽  
Intrinsic Excitability ◽  
Intrinsic Activity ◽  
Dorsal Cortex ◽  
Synchronous Activity ◽  
Mouse Cortex ◽  
Propagating Waves ◽  
Autonomous Activity

Spontaneous synchronous activity (SSA) that propagates as electrical waves is found in numerous central nervous system structures and is critical for normal development, but the mechanisms of generation of such activity are not clear. In previous work, we showed that the ventrolateral piriform cortex is uniquely able to initiate SSA in contrast to the dorsal neocortex, which participates in, but does not initiate, SSA (Lischalk JW, Easton CR, Moody WJ. Dev Neurobiol 69: 407–414, 2009). In this study, we used Ca2+ imaging of cultured embryonic day 18 to postnatal day 2 coronal slices (embryonic day 17 + 1–4 days in culture) of the mouse cortex to investigate the different activity patterns of individual neurons in these regions. In the piriform cortex where SSA is initiated, a higher proportion of neurons was active asynchronously between waves, and a larger number of groups of coactive cells was present compared with the dorsal cortex. When we applied GABA and glutamate synaptic antagonists, asynchronous activity and cellular clusters remained, while synchronous activity was eliminated, indicating that asynchronous activity is a result of cell-intrinsic properties that differ between these regions. To test the hypothesis that higher levels of cell-autonomous activity in the piriform cortex underlie its ability to initiate waves, we constructed a conductance-based network model in which three layers differed only in the proportion of neurons able to intrinsically generate bursting behavior. Simulations using this model demonstrated that a gradient of intrinsic excitability was sufficient to produce directionally propagating waves that replicated key experimental features, indicating that the higher level of cell-intrinsic activity in the piriform cortex may provide a substrate for SSA generation.

scholarly journals Rem2 stabilizes intrinsic excitability and spontaneous firing in visual circuits

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Anna R Moore ◽  
Sarah E Richards ◽  
Katelyn Kenny ◽  
Leandro Royer ◽  
Urann Chan ◽  
...  
Keyword(s):  
Neuronal Excitability ◽  
Ocular Dominance ◽  
Sensory Experience ◽  
Cellular Level ◽  
Synaptic Function ◽  
Intrinsic Excitability ◽  
Spontaneous Firing ◽  
Circuit Function

Sensory experience plays an important role in shaping neural circuitry by affecting the synaptic connectivity and intrinsic properties of individual neurons. Identifying the molecular players responsible for converting external stimuli into altered neuronal output remains a crucial step in understanding experience-dependent plasticity and circuit function. Here, we investigate the role of the activity-regulated, non-canonical Ras-like GTPase Rem2 in visual circuit plasticity. We demonstrate that Rem2-/- mice fail to exhibit normal ocular dominance plasticity during the critical period. At the cellular level, our data establish a cell-autonomous role for Rem2 in regulating intrinsic excitability of layer 2/3 pyramidal neurons, prior to changes in synaptic function. Consistent with these findings, both in vitro and in vivo recordings reveal increased spontaneous firing rates in the absence of Rem2. Taken together, our data demonstrate that Rem2 is a key molecule that regulates neuronal excitability and circuit function in the context of changing sensory experience.

scholarly journals Neuronal and synaptic plasticity in the visual thalamus in mouse models of glaucoma

2020 ◽  
Author(s):  
Matthew J. Van Hook ◽  
Corrine Monaco ◽  
Jennie C. Smith
Keyword(s):  
Mouse Models ◽  
Ganglion Cells ◽  
Brain Regions ◽  
Synaptic Function ◽  
Homeostatic Plasticity ◽  
Dorsal Lateral Geniculate Nucleus ◽  
Intrinsic Excitability ◽  
Dependent Manner ◽  
Functional Changes ◽  
Genetic Mouse Model

AbstractHomeostatic plasticity plays important roles in regulating synaptic and intrinsic neuronal function to stabilize output following perturbations to circuit activity. In glaucoma, a neurodegenerative disease of the visual system commonly associated with elevated intraocular pressure (IOP), early disease is associated with altered synaptic inputs to retinal ganglion cells (RGCs), changes in RGC intrinsic excitability, and deficits in optic nerve transport and energy metabolism. These early functional changes can precede RGC degeneration and are likely to alter RGC outputs to their target structures in the brain and thereby trigger homeostatic changes in synaptic and neuronal properties in those brain regions. In this study, we sought to determine whether and how neuronal and synaptic function is altered in the dorsal lateral geniculate nucleus (dLGN), an important RGC projection target in the thalamus, and how functional changes relate to IOP. We accomplished this using patch-clamp recordings from thalamocortical (TC) relay neurons in the dLGN in two established mouse models of glaucoma – the DBA/2J (D2) genetic mouse model and an inducible glaucoma model with intracameral microbead injections to elevate IOP. We found that the intrinsic excitability of TC neurons was enhanced in D2 mice and these functional changes were mirrored in recordings of TC neurons from microbead-injected mice. Notably, many neuronal properties were correlated with IOP in older D2 mice, but not younger D2 mice or microbead-injected mice. The frequency of miniature excitatory synaptic currents (mEPSCs) was reduced in both ages of D2 mice, and vGlut2 staining of RGC synaptic terminals was reduced in an IOP-dependent manner in older D2 mice. Among D2 mice, functional changes observed in younger mice without elevated IOP were distinct from those observed in older mice with elevated IOP and RGC degeneration, suggesting that glaucoma-associated changes to neurons in the dLGN might represent a combination of stabilizing/homeostatic plasticity at earlier stages and pathological dysfunction at later stages.

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