Figure 5: Application of ERG gain analysis to ERGs recorded from STZ-diabetic rats. Averaged group ERG waveforms showing the effect of diabetes on the (a) rod-isolated a-b wave complex and the (b) STR. (c) The thick line shows the ERG gain slope defined from the control group. Thin diagonal line shows the unity relationship. For a given reduction in input (along the -axis) the predicted downstream change is given by the arrow (along the -axis). This prediction can be compared to the measured change induced by the treatment (filled symbol) along with the 95% confidence limits (grey bar). This shows that PII loss cannot be due to photoreceptoral dysfunction. (d) Likewise, pSTR loss is greater than the PII deficits. (e) nSTR increased amplitude is not downstream of PII. (f) The delay in the PII is greater than that predicted from the PIII. (g) Delay in the pSTR can be accounted for by the PII delay. (h) nSTR delay is less than that expected from the PII delay. Asterisks (*) denote significance ( ).