Bypassing V1: a direct geniculate input to area MT.
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.
Sincich
Lawrence C
LC
Beckman Vision Center, University of California, 10 Koret Way, San Francisco, California 94143, USA. sincich@itsa.ucsf.edu <sincich@itsa.ucsf.edu>
Park
Ken F
KF
Wohlgemuth
Melville J
MJ
Horton
Jonathan C
JC
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
D002772:Cholera Toxin; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2; D017871:Calcium-Calmodulin-Dependent Protein Kinases