Effect of a differential training paradigm with varying frequencies and amplitudes on adaptation of vestibulo-ocular reflex in mice.

The vestibulo-ocular reflex (VOR) functions to maintain eye stability during head movement, and VOR gain can be dynamically increased or decreased by gain-up or gain-down adaptation. In this study, we investigated the impact of a differential training paradigm with varying frequencies and amplitudes on the level of VOR adaptation in mice. Training for gain-up (out of phase) or gain-down (in phase) VOR adaptation was applied for 60 min using two protocols: (1) oscillation of a drum and turntable with fixed frequency and differing amplitudes (0.5 Hz/2.5°, 0.5 Hz/5° and 0.5 Hz/10°). (2) Oscillation of a drum and turntable with fixed amplitude and a differing frequency (0.25 Hz/5°, 0.5 Hz/5° and 1 Hz/5°). VOR adaptation occurred distinctively in gain-up and gain-down learning. In gain-up VOR adaptation, the learned increase in VOR gain was greatest when trained with the same frequency and amplitude as the test stimulation, and VOR gain decreased after gain-up training with too high a frequency or amplitude. In gain-down VOR adaptation, the decrease in VOR gain increased as the training frequency or amplitude increased. These results suggest that different mechanisms are, at least in part, involved in gain-up and gain-down VOR adaptation.