Oscillatory potentials of visual evoked potentials using source derivation technique in rabbits.

The topographic distribution of epidurally recorded flashed visual evoked potentials (VEPs) in unanesthetized rabbits was studied using 2 montages. VEPs with linked ears reference and source derivation were compared. With the linked-ears reference, N34 of VEPs which consisted of slow potentials and superimposed oscillations were recorded diffusely over the head. When source derivation was used, the slow negative potentials of N34 present on the recordings in P3 and P4 were not obtained in F3, Fz and F4. In a digital filtering study of the oscillatory potentials, N34 in oscillatory potentials which were recorded diffusely over the head were localized to the visual cortex by source derivation. It was concluded that N34 in the oscillatory potentials generated from the visual cortex are enhanced and localized with source derivation.