We have located links that may give you full text access.
JOURNAL ARTICLE
RESEARCH SUPPORT, NON-U.S. GOV'T
Spike-wave complexes and fast components of cortically generated seizures. IV. Paroxysmal fast runs in cortical and thalamic neurons.
Journal of Neurophysiology 1998 September
In the preceding papers of this series, we have analyzed the cellular patterns and synchronization of neocortical seizures occurring spontaneously or induced by electrical stimulation or cortical infusion of bicuculline under a variety of experimental conditions, including natural states of vigilance in behaving animals and acute preparations under different anesthetics. The seizures consisted of two distinct components: spike-wave (SW) or polyspike-wave (PSW) at 2-3 Hz and fast runs at 10-15 Hz. Because the thalamus is an input source and target of cortical neurons, we investigated here the seizure behavior of thalamic reticular (RE) and thalamocortical (TC) neurons, two major cellular classes that have often been implicated in the generation of paroxysmal episodes. We performed single and dual simultaneous intracellular recordings, in conjunction with multisite field potential and extracellular unit recordings, from neocortical areas and RE and/or dorsal thalamic nuclei under ketamine-xylazine and barbiturate anesthesia. Both components of seizures were analyzed, but emphasis was placed on the fast runs because of their recent investigation at the cellular level. 1) The fast runs occurred at slightly different frequencies and, therefore, were asynchronous in various cortical neuronal pools. Consequently, dorsal thalamic nuclei, although receiving convergent inputs from different neocortical areas involved in seizure, did not express strongly synchronized fast runs. 2) Both RE and TC cells were hyperpolarized during seizure episodes with SW/PSW complexes and relatively depolarized during the fast runs. As known, hyperpolarization of thalamic neurons deinactivates a low-threshold conductance that generates high-frequency spike bursts. Accordingly, RE neurons discharged prolonged high-frequency spike bursts in close time relation with the spiky component of cortical SW/PSW complexes, whereas they fired single action potentials, spike doublets, or triplets during the fast runs. In TC cells, the cortical fast runs were reflected as excitatory postsynaptic potentials appearing after short latencies that were compatible with monosynaptic activation through corticothalamic pathways. 3) The above data suggested the cortical origin of these seizures. To further test this hypothesis, we performed experiments on completely isolated cortical slabs from suprasylvian areas 5 or 7 and demonstrated that electrical stimulation within the slab induces seizures with fast runs and SW/PSW complexes, virtually identical to those elicited in intact-brain animals. The conclusion of all papers in this series is that complex seizure patterns, resembling those described at the electroencephalogram level in different forms of clinical seizures with SW/PSW complexes and, particularly, in the Lennox-Gastaut syndrome of humans, are generated in neocortex. Thalamic neurons reflect cortical events as a function of membrane potential in RE/TC cells and degree of synchronization in cortical neuronal networks.
Full text links
Related Resources
Trending Papers
Challenges in Septic Shock: From New Hemodynamics to Blood Purification Therapies.Journal of Personalized Medicine 2024 Februrary 4
Molecular Targets of Novel Therapeutics for Diabetic Kidney Disease: A New Era of Nephroprotection.International Journal of Molecular Sciences 2024 April 4
Perioperative echocardiographic strain analysis: what anesthesiologists should know.Canadian Journal of Anaesthesia 2024 April 11
The 'Ten Commandments' for the 2023 European Society of Cardiology guidelines for the management of endocarditis.European Heart Journal 2024 April 18
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app
All material on this website is protected by copyright, Copyright © 1994-2024 by WebMD LLC.
This website also contains material copyrighted by 3rd parties.
By using this service, you agree to our terms of use and privacy policy.
Your Privacy Choices
You can now claim free CME credits for this literature searchClaim now
Get seemless 1-tap access through your institution/university
For the best experience, use the Read mobile app