A lucite plate method for 3-dimensional reconstruction of neuronal populations

A Lucite plate reconstruction method is described which, when combined with HRP histochemistry, provides an excellent means of visualizing, in 3-dimensional fashion, the functional organization of neuronal populations. Color photomicrographs of representative serial sections were made through the baboon oculomotor nucleus. Each color slide was then projected onto a 9 X 12 in. Lucite plate and the configuration of the nucleus at each representative level drawn to scale on the plates. These plates were then stacked one in front of the other yielding a see-through, 3-dimensional reconstruction of the entire nucleus. Color transparencies of every sixth HRP-processed section were made and the image of each section projected onto the Lucite plates on which the configuration of the oculomotor nucleus was previously outline. Using different colored stars to represent the neurons which supply different oculomotor muscles, the number and location of HRP-positive neurons was then plotted. The end result was an anatomically accurate 3-dimensional reconstruction of the entire labeled population of the oculomotor nucleus including the location of subnuclei that can be viewed from any side or at any angle. With adequate reference points these data can be entered into a computer graphics device, then viewed and manipulated in 3-dimensional fashion.