Abstract
To investigation the effect of linear head motion on dynamic visual acuity (DVA) of a high-speed moving target, we conducted two experiments. In the first experiment, fifty healthy subjects were asked to read sequentially-presented 3 random numerals moved left to right at 60 or 90 deg/s under three head conditions: 1) stationary, 2) voluntary linear movement from left to right, and 3) voluntary linear movement from right to left. In each condition, 40 trials were carried out and numbers of correct answers were evaluated as DVA score. Although the averaged DVA score in the three conditions were almost the same, we found higher DVA score in the trials in which head motion started more than 200ms prior to the onset of target motion under the condition 2). In the second experiment, nine healthy subjects were trained to start their head motion in time with an audio cue 300ms prior to the onset of target motion (80deg/s) under the condition 2). After this training, seven of nine subjects clearly improved DVA score, and their eyes moved in the same direction of head motion, which was the opposite direction of vestibuloocular reflex (VOR). This kind of eye-head motion was observed even in darkness in 3-4 trials jast after the training and diminished after 7-8 trials. The dynamic change in VOR and the contribution of predictive smooth pursuit eye movement to the visual acuity will be discussed. [J Physiol Sci. 2007;57 Suppl:S162]
