Abstract
Intracellular recordings were obtained using biocytin-filled electrodes from 78 neurones located in both dysplastic neocortex and subcortical heterotopic aggregates in a model of neuronal migration disorder induced in rats by means of a double methylazoxymethanol injection given on embryonic day 15. Both regular spiking and intrinsically bursting pyramidal neurones were found in all of the examined structures and were synaptically activated by subcortical stimulation. In a neuronal subpopulation (22%) located in the neocortex as well as in the subcortical heterotopic aggregates, the injection of depolarising current pulses elicited aberrant firing patterns, consisting of repetitive bursts of APs that gradually increased in duration and eventually merged in a long-lasting discharge. The gradual development of this 'excessive' bursting behaviour suggests a progressive run-down of the slow components of the hyperpolarising afterpotential.
MeSH terms
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Animals
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Cell Movement / drug effects
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Cerebral Ventricles / drug effects
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Cerebral Ventricles / pathology
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Cerebral Ventricles / physiology
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Choristoma / physiopathology*
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Culture Techniques
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Drug Administration Schedule
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Electric Stimulation
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Embryo, Mammalian / drug effects
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Evoked Potentials / drug effects
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Evoked Potentials / physiology
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Female
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Hippocampus / drug effects
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Hippocampus / pathology
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Hippocampus / physiology
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Injections, Intraperitoneal
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Intracellular Fluid / physiology*
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Maternal Exposure
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Maternal-Fetal Exchange
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Membrane Potentials / physiology
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Methylazoxymethanol Acetate / administration & dosage
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Methylazoxymethanol Acetate / analogs & derivatives*
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Methylazoxymethanol Acetate / pharmacology
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Microelectrodes
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Neocortex / drug effects*
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Neocortex / pathology
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Neocortex / physiopathology
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Neurons / classification
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Neurons / drug effects
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Neurons / physiology
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Pregnancy
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Pyramidal Cells / drug effects
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Pyramidal Cells / pathology
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Pyramidal Cells / physiology*
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Rats
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Synaptic Transmission / drug effects
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Synaptic Transmission / physiology
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Time Factors
Substances
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Methylazoxymethanol Acetate
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methylazoxymethanol