@misc{oai:ir.soken.ac.jp:00001141,
 author = {坂谷, 智也 and サカタニ, トモヤ and SAKATANI, Tomoya},
 month = {2016-02-17, 2016-02-17},
 note = {Due to the increasing use of transgenic and knockout mice in neuroscience research, it is urgently necessary to develop the technique for quantitative measurement of behaviors in mice. The video-oculography is often used to measure the eye movements of mice, but due to its limitation in temporal resolution, its use was limited to analysis of slow eye movements such as vestibuloocular reflex and optokinetic responses. As a result, rapid eye movements such as saccades have not been properly analyzed in mice as yet. To overcome such difficulties, I have newly developed a video-oculography system with high temporal resolution (240Hz) by combining high speed CCD camera with image processing software written in LabVIEW run on IBM-PC. By this recording system, the dynamic characteristics of the rapid eye movements (saccades) in alert, head-fixed mice(C57BL/6 strain) were investigated.<br />　　Mice spontaneously made rapid eye movements in the dark at a frequency of 3.2 /min  with mean amplitude of 9 degrees mainly in horizontal direction. The peak velocity of saccades increased almost linearly against the saccadic amplitude with slope of 54 / sec, whereas the saccadic duration saturated at the level of 60 msec against larger saccades.<br />　　These saccade-like rapid eye movements could be induced by the electrical stimulations of the intermediate and deep layers of the SC in a head-fixed condition. Suprathreshold current stimulus evoked mainly contraversive saccades having a roughly constant vector depending on the stimulus sites in the SC. The amplitude and the direction of evoked saccades highly depended on the initial eye position in the orbit as well as on the stimulus sites in the SC, and evoked saccades were goal-directed in mice, suggesting that eye position signals might strongly affect the dynamics of saccades in this species. Though, most sites in the SC yielded contraversive characteristic saccades, from the antero-medial region, where the visual representation of the superficial layer shared the same location in the visual field with the opposite SC, ipsiversive saccades could be induced.<br />　　For further investigation of the mechanisms underlying saccades, especially molecular mechanisms of saccade generator circuitry, the dynamic characteristics of both the spontaneous and the electrically induced saccades were examined in mice lacking a GABA-synthesizing enzyme, glutamic acid decarboxylase (GAD) 65, and a functional role of the inhibitory neurotransmitter gamma-amino butyric acid(GABA) in the saccadic system was analyzed. The peak velocity of the saccadic eye movements was significantly higher and the amplitude of saccades tended to be smaller in GAD65 knockout mice than those in wild-type animals. Moreover, significant increase in fluctuations was observed in the eye position after the termination of saccades in the GAD65 knockout mice. Prolonged electrical stimulation of the SC often evoked oscillation-like eye movements after saccades in the mutant mice. Computer simulations based on the control system model with a negative feedback loop could attribute these experimental results to the increase in the efficacy of feedback loop in the saccade generator circuitry in the downstream of the SC in GAD65 knockout mice. These results support the hypothesis that the neural system underlying the saccade generation consists of a feedback loop, and suggest that GABA plays an important role in stabilizing the saccade control system in the downstream of the SC.<br />　　The results presented in this study show that the newly developed video-oculographic system provides a powerful tool for analyzing dynamic characteristics of saccadic eye movements in mice. Furthermore, this study will provide a fundamental knowledge to study molecular basis of the oculomotor and, moreover, cognitive functions by using various lines of mutant mice., application/pdf, 総研大甲第777号},
 title = {DEVELOPMENT OF THE HIGH-SPEED VIDEO-OCULOGRAPHIC SYSTEM AND ITS APPLICATION TO THE STUDY ON THE SACCADIC EYE MOVEMENTS IN MICE},
 year = {}
}