Multifractal structure of microscopic eye-head coordination

Fixational eye movements contribute to visual processing. The information encoded in them is crucial for signals coming from fovea since it connects visual information with brain activity. We recorded microsaccades and tiny head movements at high resolution, with a sampling rate of 300 Hz. Microsaccades are likely influenced by heads's motion. Multifractal analysis shows that both movements are multiplicative processes of different origins, thereby reflecting the presence of different strategies. Microsaccades draw steps from a broad distribution of probability values, which likely indicates the way that the eyes use to maximize information, and satisfies a stretched exponential distribution. On the other hand, tiny head movements are described well by a lognormal distribution. Both movements, eye and head, are initially correlated and de-coherence of the two takes place for times greater than 29.2 seconds.