Schedule Mar 02, 2016
How the statistical properties of human motions reveal some of the workings of our nervous system
Jorge José, Indiana University

Our daily movements are made of statistical behaviors that can be studied at different time and length scales: For example, most people can easily achieve the simple task of reaching a cup in front them, but no two people will have exactly the same movements when we zoom in their trajectories at millisecond time scales. Most current movement studies are mainly based on visual observations of performances in motor tasks, which may leave out important information at finer time scales, often considered as noise. Atypical behaviors are actually highly heterogeneous in people with neurological disorders, e.g. like Autism Spectrum Disorders (ASD), Parkinson and Schizophrenia. This heterogeneity has particularly impeded developing efficient and quantitative biological diagnoses for these disorders when they are only based on human eye observations. There is thus a critical need to identify objective and data-driven biomarkers for these disorders as guides for basic biological research studies. Recent advent of high-resolution wearable sensing devices enable continuous motion recordings at milliseconds time scales, away from detection of the naked eye. Using this technology, we asked the question as to whether we could extract information leading to quantitative biomarkers for these disorders based on natural movement studies at millisecond time scales. Here I will only discuss our results for ASD individuals. By studying the movement statistics of human natural hand movements, we unraveled a new data-type characterized by the smoothness levels of the dynamics. We used correlation functions, nearest neighbor speed-spike statistics plus other statistical metrics to quantitatively characterize each individual within the spectrum. Our statistical analysis led to a parameter plane that provides an automatic screening of different ASD subjects linking it, a posteriori, with their verbal speaking abilities. We also found unexpected similarities of the ASD's movement statistics to that of their parents. Our studies are presently being used as part of a clinical trial testing for a special genetically generated Autism.

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