Generalized spike and wave (SW) activity of feline generalized penicillin epilepsy (FGPE), an experimental model of epilepsy exhibiting a sufficient degree of similarity with human generalized 3 Hz SW discharge, depends upon both cortical and thalamic mechanisms. Cortical neurons under the influence of systemic penicillin become more excitable and respond more vigorously to thalamocortical volleys normally inducing spindles or recruiting responses. This increased response of cortical neurons activates phasic recurrent inhibition which remains intact during FGPE as is shown by the preservation of antidromically evoked recurrent inhibition of pyramidal tract cells. Thus, an oscillation between periods of increased and decreased neuronal firing probability ensues which underlies SW discharge in the EEG. The cortex imposes this oscillatory pattern of neuronal discharge upon the thalamus, which by itself, however, is incapable of responding in this matter to systemic penicillin, as it appears from experiments performed in decorticated cats. Nevertheless, the thalamus is not a mere passive follower of the cortex in SW activity, since thalamocortical inputs remain necessary to maintain it. Furthermore thalamic neurons, like cortical ones, undergo a cyclically alternating pattern of increased and decreased firing probability. They display three different modes of phase-locked timing of their discharges in relation to cortical SWs and the cortical neuronal firing pattern. Two groups of cells fire coincidentally with the "spike" of the SW complex, one group reaching its maximum firing probability slightly before, the other slightly after that of the simultaneously recorded cortical neuron. The third group fires during the "wave" of the SW complex and its firing pattern is therefore about 180(DEGREES) out of phase with that of the cortical and the other two groups of thalamic neurons. Thus the substrate of generalized SW discharge seems to be oscillatory activity within a c
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.68640 |
| Date | January 1982 |
| Creators | Avoli, Massimo. |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Neurology and Neurosurgery) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 000157642, proquestno: AAINK60909, Theses scanned by UMI/ProQuest. |
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