EARLY DISCORDANT BINOCULAR VISION DISRUPTS SIGNAL TRANSFER IN THE LATERAL GENICULATE-NUCLEUS

The mammalian lateral geniculate nucleus (LGN) is known to regulate si gnal transfer from the retina to the brain neocortex in a highly compl ex manner. Besides inputs from the brainstem, extraretinal inputs via corticogeniculate projections and local inhibitory neurons modulate si gnal transfer in the LGN. However, very little is known about whether the postnatal development of LGN signal-transfer mechanisms is influen ced by early discordant binocular vision. By intraunit comparisons of responses between individual X-LGN cells and their direct retinal inpu ts, the efficiency of signal transfer was found permanently reduced du e to an early interocular misalignment (strabismus). The contrast sens itivity and spatial resolution of cat LGN cells were significantly low er relative to their retinal inputs, and there was substantial decreas e in signal-transfer speed. The observed physiological deficits were a ssociated with immature X-retinogeniculate axon arbors. Thus, contrary to previous ideas, conflicting binocular inputs can produce neural de ficits in subcortical visual structures.