Svetlana V Alekseenko
Pavlov Institute of Physiology-Russian Academy of Sciences, Russia
Title: Organization of neuronal structures for binocular vision and the dynamics of their im-pairments in the case of amblyopia
Biography
Biography: Svetlana V Alekseenko
Abstract
Statement of the Problem: One of the important tasks performed by a binocular system is reconstruction of 3-D visual space from two 2-D retinal images. This task is performed by the analysis of abso-lute and relative disparity of retinal images by binocular neurons in the visual cortex. It is known that abnormal binocular expe-rience during early childhood may produce amblyopia reducing visual acuity and ste-reovision, changing visuo-motor behaviour due to impaired formation of neuronal connections. The dynamics of these pro-cesses is not well understood yet. The purpose of our study was to investigate devel-opment of impairments in crossed and uncrossed pathways originating from each retina in feline experimental models of deprivation and dis-binocular amblyopia. Method: Using histochemical staining for cytochrome oxidase–a mitochondrial enzyme involved in energy production – the functional activity in eye-specific layers of lateral geniculate nucleus (LGN) of both hemispheres was estimated in unilaterally convergent strabismic kittens (SK) and monocularly deprived kittens (MDK) at ages of one to five months. Results: We found alterations of LGN layers activity in the projection of the en-tire visual field in MDK, but only in the projection of central 10-15 degrees in SK. In both experimental groups a relative de-crease of activity in layers innervated by uncrossed pathways from impaired eye was observed earlier than in layers inner-vated by crossed pathways from the same eye. Moreover, these changes were found in MDK at the age of two months while in SK they were found at the age of three months. Conclusion: The observed differences in development of deprivation and dis-binocular amblyopia strongly suggest the different mechanisms implicated in them. We speculate that intense stimulation of nasal visual hemi-field of the impaired eye in pre-surgical period of corrections might be useful to delay the impairments in un-crossed pathway.