Relative contributions of sustained and transient pathways to human stereoprocessing

It has been proposed [Hubel & Livingstone (1987) Journal of Neuroscience, 7, 3378-3415] that stereopsis is mediated solely by magnocellular pathway in primates. This hypothesis was evaluated for humans in psychophysical experiments with dynamic random-noise stimuli, based on the sustained/transient relationship of behavior mediated by the two divisions of the LGN [Merigan & Maunsell (1993) Annual Review of Neuroscience, 16, 369-402]. The stereoscopic limits show that stereoscopic system is more sensitive to sustained random-dot stimuli than to transient ones. Quantitative modeling of the result implied a weak role for magnocellular input, suggests that human stereopsis is more strongly influenced by parvocellular input through the LGN.