HIGH-RESOLUTION RETINOTOPIC MAPPING WITH OPTICAL IMAGING OF INTRINSIC SIGNALS IN CAT PRIMARY VISUAL CORTEX
01/29/2020
Zsolt Kocsis1, Mohit Srivastava1, Julian ML Budd2, Cyril Monier3, Yves Fregnac3, Zoltán Kisvárday1
1 MTA-Debreceni Egyetem Neuroscience Research Group, Debrecen, Hungary
2 University of Sussex, Dept. Informatics, School of Engineering and Informatics, Brighton, UK
3 CNRS-UNIC, Gif-sur-Yvette, France
Retinotopy is the representation of the visual field as projected onto the retina, then conveyed in the primary visual cortex. Our aim is to obtain high-resolution retinotopic maps in the visual cortex, in order to determine correspondence between neuronal connections and visual field polar coordinates and through this estimate their putative role in contour integration process. Anaesthetised and paralyzed cats were prepared for intrinsic signal optical imaging. Monocular visual stimuli were presented on a computer monitor, 57 cm from the animal's eye and both hemispheres imaged. A single stimulus consisted of an elongated aperture containing drifting luminance gratings (4 orientations) whose visual field position was systematically changed. In addition to this, aperture size and minimum spatial separation for two neighbouring apertures were determined using 0.25-0.5° increments, respectively. Activity images were subjected to noise reduction and normalization using cocktail-blank, first frame analysis and low-pass filtering. The resulting maps allowed us to determine the vertical meridian separating area 17/18, iso-azimuth and iso-elevation lines, and aperture size and aperture separation related activity contrast functions. Finally, high-resolution retinotopic maps were generated using a linear interpolation algorithm which returned visual field polar coordinates for an entire ROI covering several mm2 of visual cortex. We will use these high-resolution retinotopic maps to study long-range lateral connectivity of pyramidal and spiny stellate neurons in relation to visual field representation. Supported by NAP2 (2017-1.2.1-NKP-2017-00002) and TKI (Nr. 11 008)