Fig. 3.

Changes in mean VsEP response parameters following various doses of XE991. Different doses are color coded the same for all panels as marked and identified in A to aid comparisons. A: changes in vestibular response threshold over time following XE991 injection. Mean VsEP thresholds are represented as the difference from mean baseline threshold in dB re: 1 g/ms. Threshold was determined every 20 min. Each line represents the mean difference from baseline across individual animals in each dose group as a function of time. For low doses from 0.05 to 0.5 mg/kg, threshold changes were not significant during the period of enhanced latencies and amplitudes. For higher doses (3.5 to 50 mg/kg), significant threshold increases above baseline over time occurred during response suppression. B: high-resolution sampling in time. VsEPs were recorded every 2 min for the first 20 min following XE991 administration. Peripheral response components of the VsEP (P1, N1, P1-N1) are represented. Enhancement and suppression of responses developed systematically in a dose-dependent manner. Onset timing of suppression was generally between 5 and 10 min after drug. Sample sizes are as follows: 50 mg/kg, n = 5; 25 mg/kg, n = 2; 12.5 mg/kg, n = 5; 5 mg/kg, n = 6; 3.5 mg/kg, n = 6; 2.5 mg/kg, n = 5; 1 mg/kg, n = 5; 0.5 mg/kg, n = 5; 0.05 mg/kg, n = 5; and saline, n = 4. Stimulus level was +6 dB re: 1.0 g/ms.