Linear signal transmission from prepotentials to cells in the macaque lateral geniculate nucleus.

Prepotentials preceding a neuronal action potential were recorded extracellularly in the lateral geniculate nucleus (LGN) of the macaque. Although prepotentials are found less frequently in the macaque than in the cat LGN, their electrical characteristics are similar, suggesting that they represent the arrival of impulses in a retinal afferent, as in the cat. The visual response properties of prepotentials and associated cells were similar under a variety of conditions, indicating that, apart from some response attenuation, little signal processing takes place in macaque LGN. A constant fraction of prepotentials above a threshold frequency gave rise to neuronal action potentials independent of the stimuli used, so that the frequency of cell action potentials was linearly related to the frequency of prepotentials. Since the maintained discharge rates of a cell and its prepotential always fell on the linear relation, the net responses of a cell and its prepotential to visual stimuli were approximately proportional to one another.