V.V. Khrenkova - Ph.D. (Biol.) Senior Research Scientist, Southern Federal University (Rostov-on-Don, Russia). E-mail: vvkhrenkova@gmail.com V.V. Zolotukhin - Specialist of Physics, Senior Research Scientist, Southern Federal University (Rostov-on-Don, Russia). E-mail: zokhr_100@mail.ru P.V. Zolotukhin - Ph.D. (Biol.), Junior Research Scientist, Southern Federal University (Rostov-on-Don, Russia). E-mail: p.zolotukhin@gmail.com

Phylogenetic method is a widely used neurophysiological tool for studying the neuronal mechanisms of the cognitive hemispheric specialization. One of the main topics in this area is revealing sensory hemispheric specialization, including visual asymmetry. A convenient model for such studies is the frog-s mesencephalon cortex (MCC), i.e. its highest visual and integrative centre. Visual information processing in this compartment is performed in three steps: signal reception (in the superficial projectional layers of the MCC); signal characteristics analysis (in the medullar layers); characteristics clustering and signal recognition (in the deep integrative layers of the MCC). The aim of the present study was to describe distinctive features of the focal activity of the symmetric areas of the MCC during the three steps of the visual information processing. Focal potentials (FP) in response to the diffuse and shaped light stimuli of different color were registered symmetrically in the hemispheres in each of the MCC layers using the MAP32 (Plexon inc., USA) system. In the projection layers of the MCC, both diffuse and shaped stimuli induced only one or two negative waves and a late positive wave. In the sensory layers, the FP shape changed as a result of FP major waves polarity inversion. In the superficial layers, FPs had a more complex structure, higher peak asymmetry magnitude, and were more lasting than in the medullar and deep layers. The functional asymmetry varied depending on the step of the information processing: it was more pronounced in the projection layers, while less pronounced or negligible/absent in the sensory and integrative layers. These differences of the structural and temporal characteristics of the focal potential may be related to the morpho-functional features of the superficial layers, which create special conditions for elaborating generalized reactions towards any stimulus - due to the large number of axon/axon and axon/dendrite contacts. The reaction becomes more specific in the core (medullar and deep) layers, where it serves for recognizing stimuli and decision making.

 

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