Article

Bypassing V1: a direct geniculate input to area MT.

Beckman Vision Center, University of California, 10 Koret Way, San Francisco, California 94143, USA. <>
Nature Neuroscience (Impact Factor: 14.98). 11/2004; 7(10):1123-8. DOI: 10.1038/nn1318
Source: PubMed

ABSTRACT Thalamic nuclei are thought to funnel sensory information to the brain's primary cortical areas, which in turn transmit signals afresh to higher cortical areas. Here we describe a direct projection in the macaque monkey from the lateral geniculate nucleus (LGN) to the motion-selective middle temporal area (MTor V5), a cortical area not previously considered 'primary'. The constituent neurons are mostly koniocellular, send virtually no collateral axons to primary visual cortex (V1) and equal about 10% of the V1 population innervating MT. This pathway could explain the persistence of motion sensitivity in subjects following injury to V1, suggesting more generally that residual perception after damage in a primary area may arise from sparse thalamic input to 'secondary' cortical areas.

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