Spatial and temporal profile of high-frequency oscillations in posttraumatic epileptogenesis

Lin Li; Udaya Kumar; Jing You; Yufeng Zhou; Shennan A. Weiss; Jerome Engel; Anatol Bragin

Neurobiology of Disease (Dec 2021)

Spatial and temporal profile of high-frequency oscillations in posttraumatic epileptogenesis

Lin Li,
Udaya Kumar,
Jing You,
Yufeng Zhou,
Shennan A. Weiss,
Jerome Engel,
Anatol Bragin

Affiliations

Lin Li: Department of Neurology, University of California Los Angeles, CA 90095, USA; Department of Biomedical Engineering, University of North Texas, TX 76207, USA; Correspondence to: L. Li, Department of Biomedical Engineering, University of North Texas, 3940 N.Elm, Denton, TX, USA.
Udaya Kumar: Department of Neurology, University of California Los Angeles, CA 90095, USA
Jing You: Department of Biomedical Engineering, University of North Texas, TX 76207, USA
Yufeng Zhou: Department of Biomedical Engineering, University of North Texas, TX 76207, USA
Shennan A. Weiss: Depts. of Neurology, Dept. of Physiology and Pharmacology, State University of New York Downstate, Brooklyn, New York 11203, USA; Department of Neurology, New York City Health + Hospitals/Kings County, Brooklyn, NY 11203, USA
Jerome Engel: Department of Neurology, University of California Los Angeles, CA 90095, USA; Brain Research Institute, University of California, Los Angeles, CA 90095, USA; Department of Neurobiology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA; Department of Psychiatry and Biobehavioral Sciences, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
Anatol Bragin: Department of Neurology, University of California Los Angeles, CA 90095, USA; Brain Research Institute, University of California, Los Angeles, CA 90095, USA; Correspondence to: A. Bragin, Department of Neurology, University of California Los Angeles, 710 Westwood Plz, Los Angeles, CA 90095, USA.

Journal volume & issue: Vol. 161
p. 105544

Abstract

Read online

We studied the role of temporal and spatial changes in high-frequency oscillation (HFO, 80–500 Hz) generation in epileptogenesis following traumatic brain injury (TBI).Experiments were conducted on adult male Sprague Dawley rats. For the TBI group, fluid percussion injury (FPI) on the left sensorimotor area was performed to induce posttraumatic epileptogenesis. For the sham control group, only the craniotomy was performed. After TBI, 8 bipolar micro-electrodes were implanted bilaterally in the prefrontal cortex, perilesional area and homotopic contralateral site, striatum, and hippocampus. Long-term video/local field potential (LFP) recordings were performed for up to 21 weeks to identify and characterize seizures and capture HFOs. The electrode tip locations and the volume of post TBI brain lesions were further estimated by ex-vivo MRI scans. HFOs were detected during slow-wave sleep and categorized as ripple (80–200 Hz) and fast ripple (FR, 250–500 Hz) events. HFO rates and the HFO peak frequencies were compared in the 8 recording locations and across 8-weeks following TBI.Data from 48 rats (8 sham controls and 40 TBI rats) were analyzed. Within the TBI group, 22 rats (55%) developed recurrent spontaneous seizures (E+ group), at an average of 62.2 (+17.1) days, while 18 rats (45%) did not (E- group). We observed that the HFOs in the E+ group had a higher mean peak frequency than the E- group and the sham group (P < 0.05). Furthermore, the FR rate of the E+ group showed a significant increase compared to the E-group (P < 0.01) and sham control group (P < 0.01), specifically in the perilesional area, homotopic contralateral site, bilateral hippocampus, and to a lesser degree bilateral striatum. When compared across time, the increased FR rate in the E+ group occurred immediately after the insult and remained stable across the duration of the experiment. In addition, lesion size was not statistically different in the E+ and E- group and was not correlated with HFO rates.Our results suggest that TBI results in the formation of a widespread epileptogenic network. FR rates serve as a biomarker of network formation and predict the future development of epilepsy, however FR are not a temporally specific biomarker of TBI sequelae responsible for epileptogenesis. These results suggest that in patients, future risk of post-TBI epilepsy can be predicted early using FR.

Published in Neurobiology of Disease

ISSN: 0969-9961 (Print); 1095-953X (Online)
Publisher: Elsevier
Country of publisher: United States
LCC subjects: Medicine: Internal medicine: Neurosciences. Biological psychiatry. Neuropsychiatry
Website: https://www.journals.elsevier.com/neurobiology-of-disease

About the journal

Abstract

Keywords