Correlation of Cell Shape and Function in the Visual Cortex of the Cat

Abstract

FROM recordings made with microelectrodes it is known that neurones in the primary visual cortex (area 17) of the cat's brain respond to certain types of visual stimuli. An individual cell usually responds well to slits or edges of light shone at an appropriate orientation within a particular part of the visual field. Such a cell can be classified as simple, complex, or hyper-complex, in terms of the selectivity of its responses^1,2. Observations of Golgi-impregnated material have demonstrated that most cortical neurones are either stellate or pyramidal and it is natural to wonder whether the structural and functional properties of these cells are directly related. A suggestion that this may be so comes from the observation that the distribution of simple cells in different cortical layers tends to parallel the distribution of stellate cells, while a similar approximate correspondence exists between complex and pyramidal cells^1,3,4, which suggests this may be so. We have approached the problem of correlating cell structure and function more directly by injecting physiologically identified cells with a fluorescent dye, Procion yellow, using the technique developed by Stretton and Kravitz⁵. This dye spreads into even the finest processes of a cell and can give almost as clear a picture of cell morphology as a Golgi stain.