Bluntness of saccadic eye movement depending on vigilance states: examination by model simulation

In our previous research we revealed that eye velocity becomes blunt during saccade as the vigilance state gets lower. In this study we examined the bluntness of saccade velocity by simulating saccadic eye movements using a model of saccade generation. Blunt saccade was achieved by means of changing parameters of pulse generator in the model. Adequate values of the model parameters for 4 typical experiments were assumed by fitting simulated eye velocity to the experimental eye velocity. Comparison of the values of the model parameter to α power calculated from the EEG measured with saccade revealed a high correlation between characteristics of pulse generator and vigilance states. Since the pulse generator exists in pontine reticular formation, which also belongs to the controlling system of vigilance state, it was suggested from the results that decline in the activity of pulse generator in the brain stem caused the blunt saccade