GANGLION-CELL PATHWAYS FOR ROD VISION

Measurements of the acuity of rod vision made by two different techniq ues show it to vary only slightly with eccentricity. At eccentricities beyond 15 deg acuity is well predicted from the sampling properties o f the mosaic of the P-class of ganglion cells. With decreasing eccentr icity acuity falls progressively below the sampling limit of P-cells, but even at the lowest eccentricity examined (5 deg) does not reach th e limit imposed by the sampling properties of the mosaic of M-cells. A t an eccentricity of 5 deg rod vision could be supported by as few as 20% of P-cells.