PhD Scientific Days 2021

NE_I_P: Neurosciences I. Posters

High-Resolution Retinotopic Mapping with Intrinsic Signal Optical Imaging in the Cat's Primary Visual Cortex

Text of the abstract

Retinotopy represents the visual field projected onto the retina and from there to the visual cortex.
Our aim is to obtain high-resolution retinotopic maps of the cat’s primary visual cortex which can be used to assign visual field positions to neuronal connections within the imaged region.
Intrinsic signal optical imaging was performed on anaesthetized and paralyzed cats. The visual stimulus paradigm consisted of a series of apertures containing drifting luminance grating. These windows were shifted sequentially in 1.5° increments perpendicular to their longitudinal axis. This resulted in a systematic positional shift of stimulus-related cortical activity.
The signal-to-noise ratio of the activity maps was improved by normalizing them with the cocktail blank, first frame analysis and spatial filtering.
The analysis was performed in the following steps: first, the position of the vertical meridian was determined, then the iso-azimuth and iso-elevation lines, and finally, the contrast functions, which depend on the aperture size and resolution. Linear interpolation was used to generate the high-resolution retinotopic map. To compare our measurements with literature data fitting algorithms were employed in the Matlab environment. In this way, the generated proto-retinotopic map could reveal the change in cortical magnification factor as a function of eccentricity.
In conclusion, retinotopic maps can be obtained using intrinsic signal optical imaging and determine the probabilistic cortical representation of visual field positions at high spatial resolution. In turn, cortico-cortical connections which are thought to play a role in contour integration processes can be correlated with visual field positions.
Supported by NAP2(2017-1.2.1-NKP-2017-00002), TKI (Nr. 11008) and EFOP-3.6.3-VEKOP-16-2017-00009

University and Doctoral School

Debrecen University Faculty of Medicine, Doctoral School of Neurosciences