Short-term information pattern in optokinetic nystagmus amplitude time series.

In this paper we analyzed optokinetic nystagmus (OKN) signals for underlying information patterns. Fourteen OKN signals were recorded in five healthy subjects. First, we tested the correlation between nystagmus slow and fast phases. Previously, it has been suggested that the correlation is higher between the amplitude of the slow phase and the following fast phase, compared to the correlation between the fast phase and the following slow phase. However, we found no such difference. This is in agreement with the view that the saccade performed by the eye is not determined by the previous slow phase, but is free to move voluntarily in order to focus on an object of interest. Second, we analyzed the information entropy contained in the sequence of optokinetic nystagmus amplitudes, and found a short-term information pattern. Further analysis of these patterns could eventually lead to more knowledge about the vestibular and oculomotor systems.