Synaptic organization of claustral and geniculate afferents to the visual cortex of the cat.
Claustral and geniculate afferents to area 17 were labeled by anterograde axonal transport of peroxidase-conjugated wheatgerm agglutinin, and examined in the electron microscope. A peroxidase reaction protocol that led to labeling in the form of minute holes in the EM sections was used. Both types of afferents formed type 1 (presumed excitatory) synapses exclusively. In agreement with previous reports the great majority of geniculate afferents to layers 4 and 6 contacted dendritic spines. The claustral afferents to layers 1 and 6 also predominantly contacted spines. In layer 4, however, claustral afferents contacted spines and dendritic shafts about equally. The results suggest a substantial claustral input to smooth-dendrite cells in layer 4, which are thought to be inhibitory in function. This may be the circuit by which the claustrum helps to generate end-stopped cortical receptive fields (Sherk and LeVay, 1983).
D000344:Afferent Pathways / Q000648:ultrastructure*; D000818:Animals; D001370:Axonal Transport; D001369:Axons / Q000648:ultrastructure; D001479:Basal Ganglia / Q000648:ultrastructure*; D002415:Cats / Q000033:anatomy & histology*; D003712:Dendrites / Q000648:ultrastructure; D005829:Geniculate Bodies / Q000648:ultrastructure*; D007527:Isoenzymes; D008854:Microscopy, Electron; D009411:Nerve Endings / Q000648:ultrastructure; D009195:Peroxidase; D010544:Peroxidases; D013569:Synapses; D014793:Visual Cortex / Q000648:ultrastructure*; D014909:Wheat Germ Agglutinins
D007527:Isoenzymes; D014909:Wheat Germ Agglutinins; D010544:Peroxidases; D009195:Peroxidase