A METHOD FOR DETERMINING PHOTORECEPTOR SIGNAL-TO-NOISE RATIO IN THE TIME AND FREQUENCY DOMAINS WITH A PSEUDORANDOM STIMULUS

We have developed a method that utilizes repeated sequences of pseudor andomly modulated stimuli for calculation of the SNR either in the tim e or frequency domains. The method has the advantage that the distribu tion of SNR over relevant frequencies is readily observed. In addition , a SNR value, calculated as the ratio of the corresponding variances, is an estimate of the true SNR because it has been weighted by the ce ll's frequency response. The procedure offers significant advantages w hen studying signal transmission in nonspiking cells like photorecepto rs.