Classifying amygdala kindling stages using quantitative assessments of extracellular recording of EEG in rats

• Spectral powers of EEG of stages 3, 4, and 5 amygdala kindling are performed.
• Delta and theta waves in the stages of 3, 4, and 5 are higher than sham animals.
• Kindling process is accompanied by reduced high beta and gamma oscillations.
• Delta sub-band power significantly increases during generalized seizure stages.
• Theta/alpha ratio in localized SS is higher than generalized SSs and sham group.

PurposeDetermining different seizure stage specific features in a kindling model is a crucial step in developing efficient objective techniques for early prediction and treatment of seizures. This study identified and categorized kindling stages based on their electrophysiological features through processing extracellular field potentials of Amygdala rapid kindling.MethodsThirteen Wistar rats (200 ± 10 g) were divided into 2 groups including kindle (n = 7) and sham (n = 6) and respectively underwent an amygdala rapid kindling and placebo stimulation. EEG signals in each stage were classified into 7 bands: delta (0–4 Hz), theta (4–8 Hz), alpha (8–12 Hz), low beta (12–16 Hz), mid beta (16–20 Hz), high beta (20–28 Hz) and gamma (28–40 Hz). Spectral power and power of sub bands of stage 3 (localized seizure stage (SS)) and stages 4 and 5 (generalized SSs) were compared between kindling and sham groups.ResultSpectral analyses showed larger spikes in delta and theta subbands in the stages of 3, 4, and 5 of kindling, compared with sham animals. Generalized SSs contained more spikes than the localized SS in the kindling. Kindling process was accompanied by reduction in high beta and gamma oscillations and increase in delta sub band power which were significant in the generalized SSs. The theta/alpha ratio in the localized SS was higher than the generalized SSs and sham group, but the difference with the sham group was statistically significant.ConclusionOur results showed that reduced high beta and gamma and increased delta oscillations power are associated with behavioral seizure progression.