M.I. Trifonov – Dr.Sc.(Eng.), Leading Research Scientist, I.M.Sechenov Institute of Evolutionary Physiology and Biochemistry of the Russian Academy of Sciences (Saint-Petersburg)
V.L. Efimova – Ph.D. (Ped.), Principal Director of Scientific Research “Prognoz” Group Neruological Clinics (Saint-Petersburg)
It is widely believed that child’s disabilities to suit to the requirements of standard school course are entirely caused by child’s obstinacy and laziness. Actually, the child may have not intellectual disabilities at all but may have some motor problems which are rarely identified by specialists in practice. It is assumed that these problems can slow down dramatically the development of thinking and learning skills in children. One possible reason for motor problems is the neurological disorder of cyclical movement’s control, which can indirectly show itself in eye movement process. Here we propose a method to diagnose such kind of disorders that is based on the analysis of saccades (macro eye movements with the amplitude of more than 1o) during the tracking of discretely moving red colored star stimulus on the monitor screen. The stimulus moved just one minute from the center of the screen to the periphery changing its position on the screen every second, i.e. the child should follow the stimulus and fix its 60 positions. The center coordinates of the stimulus are located on the golden ratio-based spiral based on the golden angle (~137.5о). The application of this test allows us to get nearly linear temporal dependence of a distance between two stimulus successive positions on the final 30 seconds of the test period. Our analysis is based on the raw eye movement data that were collected using an EAS monocular eye tracker (LC Technologies, Inc., USA) that sampled at 60 Hz. We obtained that healthy children are able to catch the discretely moving stimulus properly and acquire 1 Hz rhythm of stimulus changing position, while the children with learning disabilities performed it less successfully. Furthermore, we found that they moved their gaze more frequently than it was required according to the test conditions. Based on these results we might reason that the time interval between two successive saccades (with amplitude up to 1o) in children with learning disabilities depends only slightly on the given frequency of changing of the stimulus position and exhibits rather random behaviors in comparison with the healthy children. We suppose that the method proposed here can get the neurological treatment of cyclical eye movement disorder and may be used as objective neurological diagnostic criteria in support of or against the neurological basis of the learning disabilities.
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