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Physiological Classification of Retinal Ganglion Cells in the Salamander Retina

dc.contributor.advisorGollisch, Tim Prof. Dr.
dc.contributor.authorOhlweiler Rozenblit, Fernando
dc.titlePhysiological Classification of Retinal Ganglion Cells in the Salamander Retinade
dc.contributor.refereeGollisch, Tim Prof. Dr.
dc.description.abstractengThe retina is a complex neural network, responsible for breaking down the visual scene into its distinctive features such as local contrast, motion and color. The retinal ganglion cells form the output layer of this network, and a typical vertebrate retina may contain more than 10 different ganglion cell types. These cells can be separated based on their anatomical or physiological properties, and each type is expected to relay information about distinct visual features to specific areas in the brain. Separating these channels of information is crucial for understanding how the visual scene is encoded, and much effort is put into classifying retinal ganglion cells. From the different strategies used to classify a ganglion cell, the physiological one -- based on the responses of the cell to light stimulation -- may be the most challenging, because physiological properties do not always discriminate between different cell types. For the salamander, previous attempts to classify retinal ganglion cells were based on their temporal filtering properties, and were successful in separating ganglion cells into coarse temporal response types. But surprisingly, only one of the types showed tiling (a mosaic arrangement) of its receptive fields. Because tiling is considered a strong signature of single cell types, I ask here whether a refined classification is possible -- and whether it yields tiling by further ganglion cell types. Spiking activity was recorded from isolated axolotl retinas using multi-electrode arrays, and more than 200 cells could be simultaneously recorded in a typical experiment. The retina was stimulated with an uncorrelated noise (white-noise) stimulus, which was used to estimate via reverse correlation the receptive field properties of the ganglion cells. Together with the autocorrelation of the spike-trains, the receptive field extent and temporal filtering properties were used to characterize the ganglion cells. While a single property did not easily distinguish between cell types, a spectral clustering algorithm  was able to classify the ganglion cells into putative types based on a combination of their properties. The identified types were then matched across retinas. At least two tiling types were consistently observed across retinas, with the remaining types showing few violations of tiling. Cell types with similar physiological properties, whose distinction would be blurred if analyzed within a single property, could be distinguished by a combination of properties. The results suggest that salamander ganglion cells can be classified when their physiological features are taken in tandem, and that tiling is a fundamental feature of ganglion cells types -- also in the salamander
dc.contributor.coRefereeWolf, Fred Prof. Dr.
dc.subject.engretinal ganglion cellsde
dc.subject.engcell classificationde
dc.subject.engmultielectrode arraysde
dc.affiliation.instituteGöttinger Graduiertenschule für Neurowissenschaften, Biophysik und molekulare Biowissenschaften (GGNB)de
dc.subject.gokfullBiologie (PPN619462639)de

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