Corticothalamic Modulation during Absence Seizures in Rats: A Functional MRI Assessment

• Published in: Epilepsia (Copenhagen) Vol. 44; no. 9; pp. 1133 - 1140
• Main Authors: Tenney, Jeffrey R., Duong, Timothy Q., King, Jean A., Ludwig, Reinhold, Ferris, Craig F.
• Format: Journal Article
• Language: English
• Published: 350 Main Street , Malden , MA 02148 , U.S.A Blackwell Science Inc 01.09.2003; Blackwell
• Subjects: Absence seizure; Anesthesia - methods; Animals; Biological and medical sciences; Cerebral Cortex - physiology; Electroencephalography - methods; Epilepsy; Epilepsy, Absence - physiopathology; fMRI; GHB; Headache. Facial pains. Syncopes. Epilepsia. Intracranial hypertension. Brain oedema. Cerebral palsy; Imaging; Magnetic Resonance Imaging - methods; Male; Medical sciences; Nervous system (semeiology, syndromes); Neural Pathways - physiology; Neurology; Rats; Rats, Sprague-Dawley; Thalamus - physiology; Wakefulness - physiology; Animal model; Nervous system diseases; Cerebral cortex; Rat; Epilepsy; Rodentia; Exploration; Petit mal; Functional analysis; Nuclear magnetic resonance imaging; Cerebral disorder; Encephalon; Vertebrata; Mammalia; Animal; Central nervous system disease; GABA; Medical imagery; Thalamus; Absence seizure-fMRI- Epilepsy-Imaging-GHB
• ISSN: 0013-9580; 1528-1167
• DOI: 10.1046/j.1528-1157.2003.61002.x

Purpose: Functional magnetic resonance imaging (fMRI) was used to identify areas of brain activation during absence seizures in an awake animal model. Methods: Blood‐oxygenation‐level–dependent (BOLD) fMRI in the brain was measured by using T2*‐weighted echo planar imaging at 4.7 Tesla. BOLD imaging was performed before, during, and after absence seizure induction by using γ‐butyrolactone (GBL; 200 mg/kg, intraperitoneal). Results: The corticothalamic circuitry, critical for spike–wave discharge (SWD) formation in absence seizure, showed robust BOLD signal changes after GBL administration, consistent with EEG recordings in the same animals. Predominantly positive BOLD changes occurred in the thalamus. Sensory and parietal cortices showed mixed positive and negative BOLD changes, whereas temporal and motor cortices showed only negative BOLD changes. Conclusions: With the BOLD fMRI technique, we demonstrated signal changes in brain areas that have been shown, with electrophysiology experiments, to be important for generating and maintaining the SWDs that characterize absence seizures. These results corroborate previous findings from lesion and electrophysiological experiments and show the technical feasibility of noninvasively imaging absence seizures in fully conscious rodents.