Multiple roles of midline dorsal thalamic nuclei in induction and spread of limbic seizures
Article first published online: 20 NOV 2007
2008 International League Against Epilepsy
Volume 49, Issue 2, pages 256–268, February 2008
How to Cite
Bertram, E. H., Zhang, D. and Williamson, J. M. (2008), Multiple roles of midline dorsal thalamic nuclei in induction and spread of limbic seizures. Epilepsia, 49: 256–268. doi: 10.1111/j.1528-1167.2007.01408.x
- Issue published online: 20 NOV 2007
- Article first published online: 20 NOV 2007
- Accepted 2007; Online Early publication November 20, 2007.
- Limbic seizures;
Purpose: 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 hippocampus
Results: 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.