Abstracts

Rationale: Epilepsy is a neurological disorder characterized by synchronization of activity throughout large areas of the brain. Previous researchers have successfully utilized acute rat cortical slices to study seizure-like events (SLEs) and the flow of activity through layers of cortex. Methods: While previous studies have almost exclusively used single electrodes to record activity, we used 3-D 60-channel multielectrode arrays (MEAs) to record activity from the layers of acute cortical slices of irradiated rats. We compared the rate and duration of SLEs as a result of dysplasia in control, low-dose irradiated, and high-dose irradiated rats. Results: While only small differences existed in the overall number and rate of SLEs between study groups, the average duration of these events was over twice as long in the high-dose group compared to control. Additionally, utilization of MEAs rather than single electrodes allowed for simultaneous monitoring of activity throughout a large area of tissue instead of one discrete location and allows for more robust data analysis techniques including difference in propagation across cortical layers. Conclusions: Using these data, we are examining causal interactions among cortical layers using Granger Causality, an analysis technique that can distinguish causal relationships among related time-series. We hypothesize that there will be changes in functional connectivity and activity flow in cortical layers in irradiated subjects compared to control.