Receptive field microstructure and dendritic geometry of retinal ganglion cells

We studied the fine spatial structure of the receptive fields of retinal ga nglion cells and its relationship to the dendritic geometry of these cells. Cells from which recordings had been made were microinjected with Lucifer yellow, so that responses generated at precise locations within the recepti ve field center could be directly compared with that cell's dendritic struc ture. While many cells with small receptive fields had dome-shaped sensitiv ity profiles, the majority of large receptive fields were composed of multi ple regions of high sensitivity. The density of dendritic branches at any o ne location did not predict the regions of high sensitivity. Instead, the i nteractions between a ganglion cell's dendritic tree and the local mosaic o f bipolar cell axons seem to define the fine structure of the receptive fie ld center.