Yves Sauve (PhD, McGill University)
(adjunct - Ophthalmology and Visual Sciences)
AHFMR Senior Scholar
7-45 Medical Sciences Building
University of Alberta
Canada T6G 2H7
Tel: 780 492-8609 (office)
Tel: 780 407-9015 (lab)
Functional assessment of degeneration and therapies in the visual system
The driving force in our lab is that it is all very well to prevent neuronal degeneration and reconstruct interrupted CNS circuitry but what are the functional impacts? In recent years, our work has changed its focus to direct attention to animal models of human retinal disease. For instance, do experimentally preserved photoreceptors display normal function? What are the repercussions of retinal circuitry remodeling (inherent to retinal degeneration) on the processing of photoreceptor outputs? This problem can be approached by doing electrophysiological studies in animal models of retinal degeneration and rescue.
We have been involved in research focusing mainly on the visual system because it provides a clear model for circuit reconstruction and functional assessment. Another reason for using the visual system is that there are numerous transgenic mice and rats that serve as models for pathologies in humans including retinitis pigmentosa (RP) and age related macular degeneration (AMD). Approaches are being developed to repair or prevent retinal degeneration in such models, with the idea that these might be transferred to the clinic. An in depth study of animal models is crucial before considering any clinical trials. As a background to such studies it is important to learn more about the impact of progressive retinal degeneration on central visual processing in order to fully appreciate what level of vision is sustained as photoreceptors are lost and what can be preserved after an experimental intervention. To this extent, we have developed a method (involving mapping visual receptive fields over the superior colliculus) that permits a point-to-point evaluation of visual function across the retina, similar to Humphrey perimetry testing in humans. The pertinence of this method is that it allows making a correlation between anatomical and functional observations at specific points in the retina. In parallel, we are applying a series of analytical electroretinogram (ERG) tests to assess the respective contribution of rods and cones to retinal function. In addition, we are recording single units in the rat primary visual cortex in order to define and characterize various receptive field properties such as spatial and temporal resolution and tuning, contrast sensitivity, orientation and direction selectivity, and organization of the receptive field surround. We also plan to setup a series of behavioral tests in order to assess these visual properties. Finally, we compare the functional data with anatomical studies of retinal circuitry using immunohistochemical markers and confocal microscopy.
Electroretinogram (ERG), single and multi-unit extracellular recordings to assess visual response properties in the CNS, behavioral assessment of visual response properties, microsurgery, anatomical tracing, immunohistochemistry, confocal microscopy.