Dynamic properties, interactions and adaptive modifications of vestibulo-ocular reflex and optokinetic response in mice

Dynamic properties of horizontal vestibule-ocular reflex (VOR) and optokine tic response (OKR) were studied in mice. The VOR was examined in the dark ( VORD), in the light (VORL) and in the condition in which most of the visual field moves synchronously with the head motion (VORF). A mouse and/or a su rrounding screen with vertical stripes was rotated sinusoidally, and the ga in and phase of eye movements were measured in wide dynamic stimulation ran ges. The working conditions of VOR and OKR were supplementary; OKR worked a t low speeds of head turn and VOR at high speeds. Examination of VORL and V ORF revealed non-linear interaction of VOR and OKR. The continuous sinusoid al head oscillation coupled with the in-phase or the out-of-phase oscillati on of the surrounding screen, decreased or increased the VORD gain, and inc reased or decreased the VORD phase lead, respectively. Continuous oscillati on of the surrounding screen increased the OKR gain and decreased the phase delay. These changes of VOR and OKR work to reduce the retinal slip. The p resent study provides fundamental information concerning the dynamic proper ties of VOR and OKR and the nature of their adaptive modifications in mice, which have been extensively used in genetic manipulation recently. (C) 200 1 Elsevier Science Ireland Ltd and the Japan Neuroscience Society. All righ ts reserved.