A modeling study on the signal transformation for the microsaccade generation
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KeywordsFiring Rate Superior Colliculus Main Sequence Rate Spike Related Pathway
During visual fixation, stationary images are thought to be input to the visual system. However the actual input images are continuously fluctuating due to miniature eye movements. The miniature eye movements consist of microsaccade, drift, and tremor . To date, while the functional roles of the miniature eye movements in perception, and their kinematic properties are gradually understood [1, 2, 3]; the mechanisms of their generation remain unknown. Here we focused on microsaccade, and constructed a model to explore the mechanisms of microsaccade generation.
Several lines of evidence assure that microsaccades share the same neuronal circuitry with saccades as they follow continuum behavioral profiles called the main sequence . In the saccade related pathway, saccade commands generated in superior colliculus are relayed to motoneurons via burst neurons (BN) that are tonically inhibited by omnipause neurons (OPN) except when saccade (i.e. fixation). Thus, we constructed a model based on the saccade model by Seung et al.  as it described explicitly excitatory/inhibitory BNs, the integrator network, and the oculomotor plant. We added OPN as a gain element, and controlled BNs activities to replicate the inter-microsaccade interval  and direction of microsaccade .
This research was supported by "The Next Generation Integrated Simulation of Living Matter" part of the Development and Use of the Next-Generation Supercomputer Project of the Ministry of Education, Culture, Sports and Technology.
This article is published under license to BioMed Central Ltd.