Back to Search
Start Over
Cortical focus drives widespread corticothalamic networks during spontaneous absence seizures in rats.
- Source :
-
The Journal of neuroscience : the official journal of the Society for Neuroscience [J Neurosci] 2002 Feb 15; Vol. 22 (4), pp. 1480-95. - Publication Year :
- 2002
-
Abstract
- Absence seizures are the most pure form of generalized epilepsy. They are characterized in the electroencephalogram by widespread bilaterally synchronous spike-wave discharges (SWDs), which are the reflections of highly synchronized oscillations in thalamocortical networks. To reveal network mechanisms responsible for the initiation and generalization of the discharges, we studied the interrelationships between multisite cortical and thalamic field potentials recorded during spontaneous SWDs in the freely moving WAG/Rij rat, a genetic model of absence epilepsy. Nonlinear association analysis revealed a consistent cortical "focus" within the peri-oral region of the somatosensory cortex. The SWDs recorded at other cortical sites consistently lagged this focal site, with time delays that increased with electrode distance (corresponding to a mean propagation velocity of 1.4 m/sec). Intra-thalamic relationships were more complex and could not account for the observed cortical propagation pattern. Cortical and thalamic sites interacted bi-directionally, whereas the direction of this coupling could vary throughout one seizure. However, during the first 500 msec, the cortical focus was consistently found to lead the thalamus. These findings argue against the existence of one common subcortical pacemaker for the generation of generalized spike-wave discharges characteristic for absence seizures in the rat. Instead, the results suggest that a cortical focus is the dominant factor in initiating the paroxysmal oscillation within the corticothalamic loops, and that the large-scale synchronization is mediated by ways of an extremely fast intracortical spread of seizure activity. Analogous mechanisms may underlie the pathophysiology of human absence epilepsy.
- Subjects :
- Action Potentials
Animals
Biological Clocks
Brain Mapping
Disease Models, Animal
Electric Stimulation
Electrodes, Implanted
Electroencephalography
Epilepsies, Partial complications
Epilepsy, Absence complications
Evoked Potentials
Evoked Potentials, Somatosensory
Nonlinear Dynamics
Rats
Rats, Inbred Strains
Signal Processing, Computer-Assisted
Time Factors
Wakefulness
Cerebral Cortex physiopathology
Epilepsies, Partial physiopathology
Epilepsy, Absence physiopathology
Nerve Net physiopathology
Thalamus physiopathology
Subjects
Details
- Language :
- English
- ISSN :
- 1529-2401
- Volume :
- 22
- Issue :
- 4
- Database :
- MEDLINE
- Journal :
- The Journal of neuroscience : the official journal of the Society for Neuroscience
- Publication Type :
- Academic Journal
- Accession number :
- 11850474