Spatiotemporal Dynamics of Complex Ictal Discharges: Insights from Human Seizure Recordings
Abstract number :
3.025
Submission category :
1. Basic Mechanisms / 1C. Electrophysiology/High frequency oscillations
Year :
2023
Submission ID :
645
Source :
www.aesnet.org
Presentation date :
12/4/2023 12:00:00 AM
Published date :
Authors :
Presenting Author: Emily Schlafly, PhD – Boston University
Edward Merricks, PhD – Columbia University Irving Medical Center; Catherine Chu, MD – Neurology – Massachusetts General Hospital; Sydney Cash, MD, PhD – Neurology – Massachusetts General Hospital, Harvard Medical School; Uri Eden, PhD – Department of Mathematics and Statistics, and Center for Systems Neuroscience – Boston University; Catherine Schevon, MD, PhD – Neurology – Columbia University Irving Medical Center; Mark Kramer, PhD – Mathematics and Statistics, and Center for Systems Neuroscience – Boston University
Rationale: Ictal discharges, high-amplitude field potential deflections during seizures, have drawn recent research attention. These complex waveforms exhibit multiple transients in the local field potential (LFP; Figure 1). Previous studies in humans typically analyze only a single transient in these complex waveforms, such as the largest amplitude transient or the transient coinciding with the largest burst of multiunit activity (MUA). Here, we investigate the mesoscale spatiotemporal dynamics of individual transients in ictal discharges recorded in patients with implanted microelectrode arrays (MEAs).
Methods: We analyze spatiotemporal features of LFP transients during ictal discharges from nine patients with temporal lobe epilepsy. Transients are detected by identifying minima in differentiated LFP signals. We define primary transients - transients occurring within 10 ms of MUA bursts - and two types of secondary transients: prepotentials (preceding primary transients) and afterpotentials (following primary transients). We examine spatiotemporal features of LFP transients including descent rate, recovery rate, width, and propagation speed/direction. Data is from an existing dataset obtained from Massachusetts General Hospital and Columbia University.
Results: We show that latencies between transients range from 20 to 80 ms, with shorter intervals between prepotentials and primary transients compared to primary transients and afterpotentials. We show that secondary transients propagate faster than primary transients (primary: 424 mm/s [95% CI: 328-548]; prepotentials: 807 mm/s [560-1165]; afterpotentials: 555 mm/s [457-675]). Primary and secondary transients propagate in similar directions (< 90° difference in 75.6% of complex discharges). Finally, we show that a subset of features (width, propagation speed, direction) of primary and secondary transients positively correlate (correlation > 0.1 for all cases, p < 0.005).
Basic Mechanisms