Inhibition can disrupt hypersynchrony in model neuronal networks.
1. Model neuronal network simulations were performed using a reduced Traub neuronal network model. In the absence of inhibition the network produced synchronous population bursting. 2. Bursting of individual neurons was dependent on 1 or more of the following: build-up of charge in the dendritic compartment, prolonged current flow through simulated NMDA associated channels, current flow through T channels. Interburst interval duration and consequent burst frequency was dependent on the density of slow after-hyperpolarizing potassium channels. 3. Addition of an inhibitory interneuron population projecting to GABAA receptors resulted in rapid desynchronization of the population, generally after only 1-2 cycles. This effect was found to be due to reduced participation in the individual population burst and to the need for multi-synaptic activation of the individual neuron in the presence of inhibition. 4. This desynchronizing effect could be offset by increasing the strength of interburst hyperpolarization either through increased density of IAHP, or through the addition of a separate inhibitory interneuron pool projected to GABAB receptors. 5. These data suggest that the synchronizing effects of inhibition may vary depending on circumstances-with desynchronization being dominant in cases characterized by large population bursts such as those seen in epilepsy.
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Department of Neurology, Wm. S. Middleton Veterans Hospital, University of Wisconsin, Madison, USA.
Lytton
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D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D018756:GABA Antagonists / Q000494:pharmacology; D058787:GABA-A Receptor Antagonists; D006624:Hippocampus / Q000166:cytology / Q000187:drug effects; D008959:Models, Neurological; D016202:N-Methylaspartate / Q000494:pharmacology; D016571:Neural Networks, Computer; D017966:Pyramidal Cells / Q000187:drug effects; D012032:Refractory Period, Electrophysiological / Q000187:drug effects / Q000502:physiology; D013569:Synapses / Q000187:drug effects / Q000502:physiology; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid / Q000494:pharmacology
D018690:Excitatory Amino Acid Agonists; D018756:GABA Antagonists; D058787:GABA-A Receptor Antagonists; D016202:N-Methylaspartate; D018350:alpha-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic Acid