Test-retest reliability of the rat N40 auditory evoked response: preliminary data

The N40 auditory evoked potential (EP) in rats has been used to develop an animal model for the study of sensory gating mechanisms. In an examination of the test-retest reliability of sensory gating indices, derived from the rat N40 EP, six rats were tested four times daily for 5 consecutive days. A paired-click paradigm (S1-S2) was used, and both the S2/S1 amplitude ratio and the S1-S2 amplitude difference measures of sensory gating capacity were calculated. Based on the means of four daily trials, reliability coefficients were as follows; r = 0.69 for S1, and r = 0.66 for S2 amplitudes. A reliability coefficient of 0.59 was found for the S1-S2 difference measure, and one of 0.47 for the S2/S1 ratio measure. These results suggest that the N40 can be used to study sensory gating, but caution has to be exercised in interpreting the data particularly in a repeated measures design.