Spectral and fractal characteristics of rat brain electrical activity after acute camphor tree essential oil administration

We investigated the rat brain activity in acute seizures evoked by camphor tree essential oil or its main constituent 1,8-cineole. The experiments were performed on adult male Wistar rats. The surgery and acute electrophysiological recordings were performed under pentobarbital sodium anesthesia. Local field potentials of cerebral and cerebellar parietal cortex were recorded before and 1 h after intraperitoneal (i.p.) camphor essential oil or 1,8-cineole administration. The rats were intraperitoneally injected with camphor essential oil (150-750 μl/kg b.w., in 1 ml of saline, i.p.) or 1,8-cineole (300-500 μl/kg b.w., in 1 ml of saline, i.p.). The digitized electrocortical signals (sampling frequency: 256 Hz) were analyzed by the Fast Fourier Transform, and were calculated Fractal dimension (FD) and Hurst exponent (H) also. Camphor essential oil (≥450 μl/kg b.w.) and 1,8-cineole (≥300 μl/kg b.w.) induced seizure-like activity with single and multiple spiking of high amplitudes in the parietal electrocorticogram and occasional clonic limb convulsions, 3-15 min after their administration. On the cerebrum, after camphor essential oil and 1,8-cineole administration, in epochs with epileptic activity, there was high increase in total power and an increase in relative power in delta (0,1-4,0 Hz) frequency range, as well as a decrease in relative power in theta (4,1-8,0 Hz), alpha (8,1-15,0 Hz), beta (15,1-32,0 Hz) and gamma (32,1-128,0 Hz) frequency ranges. It was confirmed the dominant presence of the delta (0,1- 4,0 Hz) frequency range and the values of the relative power ranged from 47 to 87 %. On the cerebellum, in epochs with epileptic activity, the relative power of the frequency ranges were behaving differently than cerebrum, as well as after administration of 1,8-cineole compared to the camphor essential oil. The differences between the cerebrum and cerebellum, as well as differences in the activities of the camphor essential oil and 1,8-cineole, were more pronounced in the parameters of fractal analysis. On the cerebrum, after camphor essential oil aministration, in epochs with epileptic activity, there was an increase in the FD value compared to the control, and the decrease on the cerebellum. In contrast, after 1,8-cineole administration there was a decrease in FD value on the cerebrum, and increase on the cerebellum. There was a dose dependence of response after the camphor essential oil and 1,8-cineole administration. On the cerebrum, increasing the d