Page 160 - AN-3-4

Advanced Neurology Non-invasive electroencephalography in rats

waveform of xylazine-induced SWDs during the post- SWDs and occasional spike-wave complexes. To validate
injection period may be linked to the clinical manifestation this technique, we analyzed ECoG results in 16 WAG/Rij
of absence epilepsy or neurobehavioral comorbidities. The rats for the presence of spontaneous SWDs during baseline
present study did not investigate the waveform patterns and and xylazine-induced SWDs. The duration of spontaneous
dynamics of intrinsic frequency modulations in xylazine- SWDs measured in 4-h intervals strongly correlated with the
induced SWDs. In rodents, time-frequency analysis of duration of xylazine-induced SWDs measured in the 6-min
xylazine-induced spike SWDs could serve as an additional post-injection interval. This demonstrates the applicability
diagnostic and monitoring tool for absence epilepsy and its of xylazine for diagnosing absence epilepsy in rats. SWDs
associated comorbidities. induced by xylazine exhibited comparable waveforms
in recordings obtained using a novel non-invasive EEG
The technology described in the present study has
several limitations. First, this technique can be employed technique and a conventional invasive ECoG technique.
only in anesthetized rats, which need to remain immobile Non-invasive EEG examinations in a larger cohort
during the EEG recording session. Alpha-2-agonists, in (n = 65 rats) demonstrated three types of absence
addition to the profound sedation effect, induce SWDs, epilepsy manifestations in rats: asymptomatic epilepsy,
which is a key feature of the current technique. Second, mild epilepsy, and severe epilepsy. The diversity of
signal disturbances can occur due to incidental rat head absence epilepsy in genetically predisposed patients is
movements. The rats were unable to tolerate the electrode well documented. We hypothesize that the phenotypic
cap, unlike humans, and the examiner had to manually variability of absence epilepsy in a cohort of genetically
hold the cap on the rat’s head (Figure 2C). In this study, prone WAG/Rij rats in the Institute of Higher Nervous
we employed a portable microamplifier (Physiobelt) that Activity and Neurophysiology RAS (Moscow, Russia)
was suitable for acquiring EEG signals non-invasively in mimics the phenotypic variability of this disease observed
anesthetized rats. in human patients.
Head movements caused disruptions in the physical Acknowledgments
contact between the skin and the sensors, resulting in signal
loss or zeroing. A few seconds following the restoration of None.
skin contact, high-voltage sine waves were observed before Funding
the acquisition of low-voltage electrical signals from the brain.
This newly developed method for rapid, non-invasive This study was supported by the Russian Science
diagnosis of absence epilepsy in rats could be advantageous Foundation, grant number 23-25-00166.
for preclinical studies. This is especially beneficial for Conflict of interest
ensuring that healthy, non-epileptic subjects are selected
as controls and for testing the potential absence seizure- Evgenia Sitnikova is an Editorial Board Member of this
inducing effects of candidate drugs. Future directions journal but was not in any way involved in the editorial
for non-invasive EEG recording technology include the and peer-review process conducted for this paper, directly
following: or indirectly. Separately, other authors declared that they
• Improvement of techniques for restraining rat subjects have no known competing financial interests or personal
to minimize movement and facilitate consistent relationships that could have influenced the work reported
electrode placement in this paper.
• Developing electrode caps that ensure close attachment Author contributions
of sensors to the scalp for better signal quality
• Devising a system for the precise positioning of Conceptualization: Evgenia Sitnikova
sensors on the rat scalp to optimize EEG recordings. Formal analysis: Evgenia Sitnikova
Investigation: All authors
5. Conclusion Methodology: Evgenia Sitnikova
This study presents a novel, non-invasive EEG-based Writing–original draft: Evgenia Sitnikova
technique for rapidly diagnosing absence epilepsy in Writing–review & editing: Evgenia Sitnikova
genetically predisposed rats. This method utilizes the sedative
effects of xylazine and its distinct ability to induce SWDs. Ethics approval and consent to participate
Systemic administration of xylazine in low doses (2 – 8 mg/ The Ethics Committee of the Institute of Higher Nervous
kg) induced continuous 8 – 10-Hz SWDs in symptomatic Activity and Neurophysiology of the Russian Academy of
WAG/Rij rats. Asymptomatic rats exhibited brief 6-Hz Sciences (RAS) in Moscow, Russia, approved all phases of

Volume 3 Issue 4 (2024) 10 doi: 10.36922/an.4464