The dependency of simultaneously recorded retinal and cortical potentials on temporal frequency.

To optimize the simultaneous recording of retinal and cortical potentials, we tried to identify the most sensitive condition for pattern-electroretinogram (PERG) and pattern visual evoked potential (VEP) concerning the temporal frequency. In the same session PERGs and VEPs were elicited by checkerboard patterns with 5 temporal frequencies ranging from 8 rps to 33 rps. For data analysis the steady-state responses were Fourier analysed. We evaluated whether a statistically significant response was present, estimated the magnitude of the response at the stimulus frequencies tested and estimated it's significance. For PERG less dependence on temporal frequency was evident compared to VEP. The magnitude of the VEP response was larger than that of the PERG. However the rate of statistically significant responses for the PERG compared to that of the VEP was similar for the small checksize and even higher for the large checksize. The results permit a simultaneous recording in the range of temporal frequencies, where high responses are acquired from both levels, retinal and cortical.