Prepulse inhibition in CXB recombinant inbred strains. In the top panel, startle amplitude was measured against a quiet background to avoid effects due to differences in hearing (n = 10 per strain). Startle amplitude was significantly (P = 0.002) different across RI strains. Error bars = standard error of the mean. In the bottom panel, recombinant inbred (RI) mice (n = 9 or 10 per strain) were tested for prepulse inhibition (PPI) by using stimuli of 30, 45, and 60 dB instead of 5 or 10 dB above a 60-dB background, to allow more sensitive determination of whether differences in PPI were due to hearing loss or general deficits in sensory gating. PPI inhibition was significantly (P = 0.05) different across the RI strains, and a significant (P = 0.002) strain × PPI intensity interaction was detected.