| Abstract [eng] |
A lot of contemporary neuroscience research focuses on the mechanisms by which cortical neurons obtain their well-known response properties. There is a common agreement that multiple mechanisms can play a role, but we do not yet understand their relative contributions. The aim of this thesis is to investigate effects of stimulus context and behavioral context on information processing in the early visual system of the mouse. In this work, we show how visual responses are changed by internal context as surround suppression and external context as a brain state. As a brain state here we focus not only on how anesthesia and awake states influence visual processing, but also divide the awake state into stationary and locomotion. To investigate these issues, we used in-vivo extracellular recordings and circuit disruption method (optogenetics) in mice. We noticed that there is laminar profile of spatial integration (SI) in mouse primary visual cortex: receptive field (RF) center size is smallest and surround suppression (SS) is strongest in superficial layers. Also, the strength of SS increases over time. Under anesthesia the laminar specificity of SI is decreased, the strength of SS is reduced, RF size is increased. Activation of parvalbumin cells also increases the size of pyramidal cells’ RF and decreases SS strength. We are the first to show that locomotion-based response enhancements occur already at the level of the thalamus. Finally, we showed that pupil size increases with locomotion speed. |
