Biology subjects

Gutkin, B.

Publications and source records attributed to Gutkin, B..

4 recordsLinked to original sources

bioRxiv2018

Adaptation and inhibition control pathological synchronization in a model of focal epileptic seizure

Pharmacoresistant epilepsy is a common neurological disorder in which increased neuronal intrinsic excitability and synaptic excitation lead to pathologically synchronous behavior in the brain. In the majority of experimental and theoretical epilepsy models, epilepsy is associated with reduced inhibition in the pathological neural circuits, yet effects of intrinsic excitability are usually not explicitly analyzed. Here we present a novel neural mass model that includes intrinsic excitability in the form of spike-frequency adaptation in the excitatory population. We validated our model using local field potential data recorded from human hippocampal/subicular slices. We found that synaptic conductances and slow adaptation in the excitatory population both play essential roles for generating seizures and pre-ictal oscillations. Using bifurcation analysis, we found that transitions towards seizure and back to the resting state take place via Andronov-Hopf bifurcations. These simulations therefore suggest that single neuron adaptation as well as synaptic inhibition are responsible for orchestrating seizure dynamics and transition towards the epileptic state.\n\nSignificance statementEpileptic seizures are commonly thought to arise from a pathology of inhibition in the brain circuits. Theoretical models aiming to explain epileptic oscillations usually describe the neural activity solely in terms of inhibition and excitation. Single neuron adaptation properties are usually assumed to have only a limited contribution to seizure dynamics. To explore this issue, we developed a novel neural mass model with adaption in the excitatory population. By including adaptation and intrinsic excitability together with inhibition in this model, we were able to account for several experimentally observed properties of seizures, resting state dynamics, and pre-ictal oscillations, leading to improved understanding of epileptic seizures.

neuroscience↗

bioRxiv2018

Nicotinic modulation of hierarchal inhibitory control over prefrontal cortex resting state dynamics: modeling of genetic modification and schizophrenia-related pathology

Nicotinic acetylcholine receptors (nAChRs) strongly modulate the cholinergic drive to a hierarchy of inhibitory neurons in the superficial layers of the PFC, critical to cognitive processes. Genetic deletion of various types of nAChRs, located on specific interneurons, impacts the properties of ultra-slow transitions between high and low activity states (H-states and L-states, respectively), recorded in mice during quiet wakefulness. In addition, recent data indicate that a genetic mutation of the 5 nAChR subunit located on vasoactive intestinal polypeptide (VIP) inhibitory neurons, the rs16969968 single nucleotide polymorphism (5 SNP), appears to be responsible for \"hypofrontality\" observed in schizophrenia. Chronic nicotine application to 5 SNP mice restores neural activity to control levels. Using firing rate models of hierarchically organized neural populations, we showed that the change of activity patterns recorded in the genetically modified mice can be explained by a change of activity state stability, differentially modulated by cholinergic inputs to parvalbumin (PV), somatostatin (SOM) or VIP inhibitory populations. A change in amplitude, but not duration of H-states fully account for the lowered pyramidal (PYR) firing rates recorded in 5 SNP mice. We demonstrate that desensitization and upregulation of {beta}2 nAChRs located on SOM interneurons, but not activation of 5 nAChRs located on VIP interneurons, by chronic nicotine application could account for activity normalization recorded in 5 SNP mice. The model implies that subsequent nicotine withdrawal should lead to PYR activity depression more severe than the original hypofrontality caused by SNP mutation.

systems biology↗

bioRxiv2018

Development of inhibitory synaptic delay drives maturation of thalamocortical network dynamics

Nervous system maturation occurs on multiple levels, synaptic, circuit, and network, at divergent time scales. For example, many synaptic properties mature gradually, while emergent network dynamics, as data show, change abruptly. Here, we combine experimental and theoretical approaches to investigate a sudden transition in spontaneous thalamocortical activity necessary for the development of vision. Inspired by in vivo measurements of time-scales and amplitudes of synaptic currents, we extend the Wilson and Cowan model to take into account the relative onset timing and amplitudes of inhibitory and excitatory neural population responses. We study the dynamics of this system and identify the bifurcations as the onset timescales of excitation and inhibition are varied. We focus on the specific typical developmental changes in synaptic timescales consistent with the experimental observations. These findings argue that the inhibitory timing is a critical determinant of thalamocortical activity maturation; a gradual decay of the ratio of inhibitory to excitatory onset time below one drives the system through a bifurcation that leads to a sudden switch of the network spontaneous activity from high-amplitude oscillations to a non-oscillatory active state. This switch also drives a marked change to a linear network response to transient stimuli, agreeing to the in vivo observations. The switch observed in the model is representative of the sudden transition in the sensory cortical activity seen early in development.

neuroscience↗

bioRxiv2017

Circuit-level Mechanisms of EtOH-dependent dopamine release.

Alcoholism is the third leading cause of preventable mortality in the world. In the last decades a large body of experimental data has paved the way to a clearer knowledge of the specific molecular targets through which ethanol (EtOH) acts on brain circuits. Yet how these multiple mechanisms play together to result in a dysregulated dopamine (DA) release under alcohol influence remains unclear. In this manuscript, we delineate potential circuit-level mechanisms responsible for EtOH-dependent increase and dysregulation of DA release from the ventral tegmental area (VTA) into nucleus accumbens (Nac). For this purpose, we build a circuit model of the VTA composed of DA and GABAergic neurons, that integrate external Glutamatergic (Glu) inputs to result in DA release. In particular, we reproduced a non-monotonic dose dependence of DA neurons firing activity on EtOH: an increase in firing at small to intermediate doses and a drop below baseline (alcohol-free) levels at high EtOH concentrations. Our simulations predict that a certain level of synchrony is necessary for the firing rate increase produced by EtOH. Moreover, EtOHs effect on the DA neurons firing rate and, consequently, DA release can reverse depending on the average activity level of the Glu afferents to VTA. Further, we propose a mechanism for emergence of transient (phasic) DA peaks and the increase in their frequency in EtOH. Phasic DA transients result from DA neuron population bursts, and these bursts are enhanced in EtOH. These results suggest the role of synchrony and average activity level of Glu afferents to VTA in shaping the phasic and tonic DA release under the acute influence of EtOH and in normal conditions.

neuroscience↗