Binocular response modulation in the lateral geniculate nucleus. Issue 3 (9th March 2018) - Dougherty, Kacie
Abstract: The dorsal lateral geniculate nucleus of the thalamus (LGN) receives the main outputs of both eyes and relays those signals to the visual cortex. Each retina projects to separate layers of the LGN so that each LGN neuron is innervated by a single eye. In line with this anatomical separation, visual responses of almost all of LGN neurons are driven by one eye only. Nonetheless, many LGN neurons are sensitive to what is shown to the other eye as their visual responses differ when both eyes are stimulated compared to when the driving eye is stimulated in isolation. This, predominantly suppressive, binocular modulation of LGN responses might suggest that the LGN is the first location in the primary visual pathway where the outputs from the two eyes interact. Indeed, the LGN features several anatomical structures that would allow for LGN neurons responding to one eye to modulate neurons that respond to the other eye. However, it is also possible that binocular response modulation in the LGN arises indirectly as the LGN also receives input from binocular visual structures. Here we review the extant literature on the effects of binocular stimulation on LGN spiking responses, highlighting findings from cats and primates, and evaluate the neural circuits that might mediate binocular response modulation in the LGN. Abstract : Our brains combine the signals from the two eyes to create a singular view. Where the separate streams from the two eyes meet in the primate brain is unclear, with debate centering on whether the signals from the two eyes remain separate within the main target of retinal projections, the lateral geniculate nucleus (LGN). Here we review the effects of binocular stimulation on LGN neurons and evaluate neural circuits that might mediate binocular interactions in this structure.