Spike activity was simultaneously recorded from pairs of units consisting of both optic tract fibers and relay cells in the cat dLGN. The unit pairs were classified with regard to the types of receptive fields involved, the relative location of receptive fields, and their occular drive. Statistical dependencies between the discharge patterns of the simultaneously observed units were assessed by computing their auto- and crosscorrelogram during a period of maintained discharge. Two distinctly different types of statistical dependence were observed. Unit pairs having like and overlapping receptive field centers exhibited statistical dependencies manifested in their crosscorrelograms by a peak near the origin. Conversely, unit pairs having opposite and overlapping receptive field centers were characterized by a prominent valley in their crosscorrelograms near the origin. These statistical dependencies are inferred to represent functional interaction most probably occurring in the retina and characterized by a common element exerting an influence on both units.