Project 18

Organisation of corticotectal projections in ephrin-A-/- mice

Genetically modified mice that lack one or more ephrin-As, key axon guidance proteins required for the establishment of topographic connections between the retina and visual targets in the brain, have disordered visual system circuitry. We will use this model to address the relationship between brain structure and function. Developmental disruption of the topographic map alters the subsequent alignment of SC maps for other sensory modalities, but the impact on the pattern of visual corticotectal projections has not been addressed in ephrin-A knockout mice. We will inject tracers into different parts of primary visual cortex in ephrin-A2, A5 and A2/A5 mice and examine the pattern of termination of corticotectal axons in the SC, relating any errors to known errors in retinotectal targeting. Methods: Anterograde tracing in different visuotopic parts of the visual cortex. Cryosectioning, immunohistochemistry. Electrophysiological recording.