Sensory gating in rats: Lack of correlation between auditory evoked potential gating and prepulse inhibition

This study was designed to evaluate the possible similarities between two p aradigms designed to measure sensory gating: (1) an auditory evoked potenti al (AEP), called the P-50 gating paradigm; and (2) an acoustic startle (ASR ), called the prepulse inhibition paradigm. These paradigms show a number o f methodological, pharmacological, and neurobiological similarities, and th ey are both disturbed in patients with schizophrenia. In the first of three experiments, the AEP gating and the ASR gating were measured in rats. Alth ough both AEP and ASR gating could readily be obtained, there appeared to b e no correlation between the performance in these two paradigms. This lack of correlation was confirmed using a factor analytical approach, where the AEP gating and the ASR gating parameters were found to load on different fa ctors. In the second experiment, the interstimulus interval in the ASR para digm was increased to 500 ms (identical to the interstimulus interval of th e AEP gating paradigm). This increase reduced the degree of ASR gating, alt hough some gating could still be obtained. Again no correlation was found b etween AEP and ASR gating, and this was again confirmed by the factorial an alysis. In the final experiment, the effects of the dopamine D-2/3 agonist 7-OHDPAT were evaluated in both paradigms. This selective agonist dose depe ndently reduced ASR gating but had no effect on AEP gating. Together, these data strongly suggest that AEP and ASR gating measure two different aspect s of information processing and indicate that both paradigms may be importa nt for investigating the neurobiological disturbances observed in patients with psychoses.