Changes of Visually Evoked Potentials in Rats after Brain Trauma
In this study, we compared visually evoked potentials (VEP) in healthy rats and rats following traumatic brain injury. Traumatic brain injury was modelled by the method of controlled cortical impact. The electrical activity of the brain cortex was registered using nichrome electrodes. Responses in primary and secon dary motor cortex areas, as well as in the area of primary sensory cortex over the hippocampus, were evoked by 3 Hz white light fl ashes on the 3rd and 7th day after the operation. The latencies and amplitudes of N1, P2, N2, P3 и N3, as well as the duration and amplitudes of inter-peak intervals, were calculated. It is shown that unilateral traumatic damage of the motor cortex area and underlying regions in rats does not signifi cantly reduce the number of VEP peaks. However, in most of the animals, the N1 component was absent in the area of damage.In comparison with healthy rats, traumatized rats demonstrated an increased latency of N1 and N3 peaks on the 3rd day after the operation followed by their return to normal values on the 7th day. In addition, traumatized rats showed a higher P2 amplitude in regions remote from the traumatized cortex area on the 3rd day; however, the P2 amplitude was lower in the injury area on the 7th day. The obtained results indicate that the registration and analysis of VEP can be used for localizing the traumatized area and to analyse the dynamics of the brain functional state in rats with brain trauma.