Quantitative assessments of extracellular EEG to classify specific features of main phases of seizure acquisition based on kindling model in Rat

Abstract

Objective: Quantitative assessments of extracellular EEG to identify specific features of three main phases of seizure acquisition based on kindling model in Rat.

Methods: Male rats were divided into 2 groups including kindled (n=10) and sham (n=7) and respectively underwent an amygdala rapid kindling and placebo kindling. EEG signals in stages 1-2 (initial seizure stages (ISSs)), 3 (localized seizure stage (LSS)), and 4-5 generalized seizure stages (GSSs) were divided into 5 bands: delta (0-4Hz), theta (4-8Hz), alpha (8-12Hz), beta (12-28Hz), and gamma (28-40Hz). Spectral power of the sub bands and the ratios of theta/alpha and delta/beta were compared in the three phases and between the sham and kindling groups.

Results: Beta power significantly increased during kindling acquisition, though it was significantly lower than sham. Delta oscillation in ISSs was higher than LSS and GSSs, but the difference was significant only with LSS. Moreover, delta power was higher in all stages of kindling than sham. Gamma power in all stages of kindling was significantly lower than sham. Alpha power was significantly reduced in ISSs, compared with sham, but gradually increased during epileptogenesis. Theta/alpha and delta/beta increased in all stages, compared with sham (p<0.05). Theta/alpha significantly decreased in LSS and GSSs, compared with ISSs (p<0.05). Delta/beta decreased during kindling, but it was significantly different only between ISSs and LSS (P<0.05).

Conclusion: Beta and alpha oscillations at ISSs significantly decreased, but gradually increased along with kindling progression. Furthermore, delta power significantly increased during kindling process.

Keywords: Afterdischarge; Electroencephalogram; Kindling; Power spectrum; Quantitative assessment.