The parvocellular LGN provides a robust disynaptic input to the visual motion area MT.
Dorsal visual cortical areas are thought to be dominated by input from the magnocellular (M) visual pathway, with little or no parvocellular (P) contribution. These relationships are supported by a close correlation between the functional properties of these areas and the M pathway and by a lack of anatomical evidence for P input. Here we use rabies virus as a retrograde transynaptic tracer to show that the dorsal area MT receives strong input, via a single relay, from both M and P cells of the lateral geniculate nucleus. This surprising P input, likely relayed via layer 6 Meynert cells in primary visual cortex, can provide MT with sensitivity to a more complete range of spatial, temporal, and chromatic cues than the M pathway alone. These observations provide definitive evidence for P pathway input to MT and show that convergence of parallel visual pathways occurs in the dorsal stream.
Nassi
Jonathan J
JJ
Systems Neurobiology Laboratories, The Salk Institute for Biological Studies, 10010 North Torrey Pines Road, La Jolla, California 92037, USA.
Lyon
David C
DC
Callaway
Edward M
EM
D000818:Animals; D005829:Geniculate Bodies / Q000033:anatomy & histology* / Q000502:physiology; D008251:Macaca; D008297:Male; D009039:Motion Perception / Q000502:physiology*; D009474:Neurons / Q000166:cytology / Q000378:metabolism; D013569:Synapses / Q000502:physiology; D014793:Visual Cortex / Q000033:anatomy & histology* / Q000502:physiology; D014795:Visual Pathways / Q000033:anatomy & histology* / Q000502:physiology