Visual evoked potential frequency content: Effect of lysolecithin induced demyelination in rat optic chiasm

Visual evoked potential (VEP) is an effective tool in order to study the visual pathways. This study was performed to evaluate VEP frequency content and the effect of demyelination induction in optic chiasm in rats.
VEPs for 61 normal adult female Wistar rats (8-10 weeks) were recorded in the equal conditions and the component latencies of the mean VEPs were studied. Then, the VEP frequency content was evaluated in frequency space through Fast Fourier transforming. Meaningly, to evaluate the effect of the demyelination induction on VEP frequency content, two groups (n = 6 for each group) of rats were selected randomly and divided into the experimental and sham groups. The experimental group was injected lysolecithin into optic chiasm to induce demyelination. The sham group received saline injection into the optic chiasm. Correspondingly, VEP content compared between two groups before injection (day 0) and on days 3, 7, 14 and 21 post-lesion.
The study of the VEP frequency content indicated delta and beta band power have the maximum (67.65±2.42) and minimum (4.36±0.5) percent in VEP frequency band powers, respectively. Moreover, the comparison between experimental and sham groups showed the decrease of beta band relative power on days 3 and 14 post-lesion in experimental group (p It seems that the VEP evaluation in frequency space can reveal the lysolecithin-induced demyelination effects before these effects are revealed in time space