Three-dimensional form and a simple, interrupted flat map of a single layer in the lateral geniculate nucleus of the...

A simple, computer-based procedure is described for measuring the 3-dimensional (3D) coordinates and making two-dimensional (2D) flat maps of a curved surface representing the middle depth of layer A1 in the lateral geniculate nucleus (LGN) of the cat. The surface was defined from histological sections and flattened by tiling it with small triangular tiles which were then laid in a single plane to form several flat strips or lunes. Though the resultant maps are discontinuous (interrupted), they preserve total area to within a few percent, have constant scales throughout and closely approximate true shape within individual tiles. The results represent a step in assessing the potential contribution of form to visual function in the LGN. They provide graphic 3D and 2D images of the complex shape of a single layer and a quantitative framework for constructing models of geniculocortical processing that can incorporate the 3D form of the LGN as well as other anatomical and physiological data.