Seyed Reza Mousavi1, Justin A Arcaro2, L Stan Leung3, Jeffrey R Tenney4, Seyed M Mirsattari5. 1. Department of Clinical Neurological Sciences, University of Western Ontario, London, Ontario, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada. Electronic address: mousavi.1982@gmail.com. 2. Department of Clinical Neurological Sciences, University of Western Ontario, London, Ontario, Canada; Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada; Graduate Program in Neuroscience, University of Western Ontario, London, Ontario, Canada. Electronic address: justin.arcaro@gmail.com. 3. Department of Physiology and Pharmacology, University of Western Ontario, London, Ontario, Canada; Graduate Program in Neuroscience, University of Western Ontario, London, Ontario, Canada. Electronic address: sleung@uwo.ca. 4. Department of Pediatrics, Division of Neurology, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA. Electronic address: Jeffrey.Tenney@cchmc.org. 5. Department of Clinical Neurological Sciences, University of Western Ontario, London, Ontario, Canada; Graduate Program in Neuroscience, University of Western Ontario, London, Ontario, Canada; Department of Medical Biophysics, Western University, London, Ontario, Canada; Department of Medical Imaging, Western University, London, Ontario, Canada; Department of Psychology, Western University, London, Ontario, Canada. Electronic address: Seyed.Mirsattari@lhsc.on.ca.
Abstract
OBJECTIVE: Using the gamma-butyrolactone (GBL) rat model of absence seizures, this study investigated the functional connectivity of the hippocampus, thalamus and cerebral cortex before and during absence seizures. METHODS: Functional connectivity between the hippocampus, thalamus and sensory and motor cortecies, were examined by the temporal correlations of the resting state blood-oxygen-level-dependent (BOLD) signal. Functional connectivity between these regions was calculated at baseline, 5min after saline injection, and at 5, 20 and 52min after GBL injection. This time interval spans the onset of behaviours including chewing and staring spells associated with GBL-induced absence seizures, along with the onset and suppression of spike-and-wave discharges (SWDs). RESULTS: Overall there was an increase in functional connectivity across most regions. The functional connectivity generally decreased over time and it returned to baseline 52min post-GBL injection. Functional connectivity of the thalamus to the sensory and motor cortecies increased during absence seizure. The results revealed enhanced connectivity of the left dorsal hippocampus and the thalamus shortly after GBL injection, which coincided with the appearance of SWDs in this rat model. SIGNIFICANCE: Increased functional connectivity between the hippocampus and the thalamus suggests that the hippocampus participates in the GBL model of absence seizures. Involvement of the hippocampus during absence seizure has implications for studies into the mechanisms in cognitive impairments in patients with absence epilepsy.
OBJECTIVE: Using the gamma-butyrolactone (GBL) rat model of absence seizures, this study investigated the functional connectivity of the hippocampus, thalamus and cerebral cortex before and during absence seizures. METHODS: Functional connectivity between the hippocampus, thalamus and sensory and motor cortecies, were examined by the temporal correlations of the resting state blood-oxygen-level-dependent (BOLD) signal. Functional connectivity between these regions was calculated at baseline, 5min after saline injection, and at 5, 20 and 52min after GBL injection. This time interval spans the onset of behaviours including chewing and staring spells associated with GBL-induced absence seizures, along with the onset and suppression of spike-and-wave discharges (SWDs). RESULTS: Overall there was an increase in functional connectivity across most regions. The functional connectivity generally decreased over time and it returned to baseline 52min post-GBL injection. Functional connectivity of the thalamus to the sensory and motor cortecies increased during absence seizure. The results revealed enhanced connectivity of the left dorsal hippocampus and the thalamus shortly after GBL injection, which coincided with the appearance of SWDs in this rat model. SIGNIFICANCE: Increased functional connectivity between the hippocampus and the thalamus suggests that the hippocampus participates in the GBL model of absence seizures. Involvement of the hippocampus during absence seizure has implications for studies into the mechanisms in cognitive impairments in patients with absence epilepsy.