title: Bypassing V1: a direct geniculate input to area MT.
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.
authors.affiliation: Beckman Vision Center, University of California, 10 Koret Way, San Francisco, California 94143, USA. sincich@itsa.ucsf.edu <sincich@itsa.ucsf.edu>
authors.forename: Lawrence C
authors.initials: LC
authors.lastname: Sincich
authors.forename: Ken F
authors.initials: KF
authors.lastname: Park
authors.forename: Melville J
authors.initials: MJ
authors.lastname: Wohlgemuth
authors.forename: Jonathan C
authors.initials: JC
authors.lastname: Horton
mesh_terms: D000818:Animals; D001369:Axons / Q000648:ultrastructure; D001931:Brain Mapping; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002772:Cholera Toxin; D003712:Dendrites / Q000648:ultrastructure; D005829:Geniculate Bodies / Q000502:physiology*; D007150:Immunohistochemistry; D008253:Macaca mulatta / Q000033:anatomy & histology* / Q000502:physiology; D008297:Male; D009039:Motion Perception / Q000502:physiology; D009473:Neuronal Plasticity / Q000502:physiology; D009474:Neurons / Q000166:cytology / Q000502:physiology; D013702:Temporal Lobe / Q000033:anatomy & histology* / Q000502:physiology; D015354:Vision, Low / Q000503:physiopathology; D014793:Visual Cortex / Q000033:anatomy & histology* / Q000502:physiology; D014795:Visual Pathways / Q000033:anatomy & histology* / Q000502:physiology
chemical_list: D002772:Cholera Toxin; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases