Functional recovery after nerve transplantation to optic nerve

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Reconstruction of visual pathway can be achieved by the peripheral nerve transplantation to the cut end of the optic nerve. It has been reported that the restored visual pathway can conduct some visual information such as light-dark. In this research we have tried to evaluate motion information can be processed by the restored visual system, using prepulse inhibition with a motion stimulus as a prepulse. To obtain this result, animal's visual field should be fixed. Thus we have tried to record prepulse inhibition under alpha-chloralose anesthesia. However, clear prepulse effects could not be obtained in this condition in normal control rats. Next, we have tried to evaluate detection of motion stimulus using shuttle-box avoidance task. A motion of sine-wave gratings was used as a conditioned stimulus. Unconditioned stimulus was a shock from the floor of the box. Clear learning curves have been obtained with a motion speed of 40, 20, 1.5,0.5 deg/s, showing avoidance rate of 55-70% at the 5th day of training. Nine transplanted rats have been tested using prepulse inhibition with a white LED as a prepulse. One rat showed a tendency of inhibition effect. This rat was tested in the shuttle-box using a motion stimulus of 20 deg/s. Avoidance rate increased as progress of training sessions. After the test with 20 deg/s, same training has been done with a motion speed of 40 deg/s. However, no learning effect was observed. Another transplanted rat, showing no prepulse effect to LED prepulse was tested as a control for shuttle-box task. No improvement of avoidance rate has been observed. These results suggest that some transplanted rat might be able to detect motion