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Multiple roles of midline dorsal thalamic nuclei in induction and spread of limbic seizures
Author(s) -
Bertram Edward H.,
Zhang DeXing,
Williamson John M.
Publication year - 2008
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/j.1528-1167.2007.01408.x
Subject(s) - neuroscience , kindling , amygdala , thalamus , muscimol , limbic system , limbic lobe , bicuculline , hippocampal formation , psychology , epilepsy , medicine , central nervous system , agonist , gabaa receptor , receptor
SummaryPurpose: Studies have suggested that the medial dorsal nucleus of the thalamus plays a role in the behavioral expression of limbic seizures, but it is unclear whether this region is a key component for the primary seizure circuitry or a path for seizure spread from one region to another. This study was undertaken to determine the potential role of this region in limbic seizure activity.Methods: Adult male rats received kindling stimulation either under urethane anesthesia or while awake. Glutamate or its agonists or the GABA antagonist bicuculline or agonist muscimol were infused into the medial dorsal nucleus. In another series, kindling acquisition was compared among three thalamic sites as well as with the amygdala and hippocampusResults: Drugs that enhanced excitatory drive or blocked GABA resulted in significant prolongation of electrographic seizure activity compared to saline infused controls. Enhanced GABA activity resulted in a significant reduction of seizure duration. Infusion of the compounds lateral to the medial dorsal nucleus did not affect seizure duration. In the kindling studies the medial dorsal region is the only thalamic nucleus from which hippocampal seizures can be induced, but with an elevated afterdischarge threshold compared to the two limbic sites. However, the seizures generalized more rapidly from the medial dorsal region.Conclusions: This study demonstrates that the medial dorsal nucleus and other dorsal midline nuclei have a significant role in the primary seizure circuits of limbic seizures as well as in spread of seizure activity to other regions.