Zonal organization of the ventral lateral geniculate nucleus in the cat: cholera toxin mapping.
A zonal organization of the ventral lateral geniculate nucleus (LGNv) in the cat was studied with the bidirectional tracing method by using the subunit b of cholera toxin (CTb) as the marker. The prime objectives of the present study were to examine precise distribution of terminals of the retinal afferents to the LGNv, and to correlate it with the origins and terminations of the other central connections of the nucleus. The results obtained are summarized as follows: (1) the LGNv of the cat is divided into 3 zones according to the terminations of retinal afferents: lateral, intermediate, and medial; (2) the lateral zone receives afferents from the retina in which ipsi- and contralateral fibers terminate in a complementary fashion. According to the density of labeling of retinal terminals, the lateral zone is further divided into several areas. It also receives fibers from the visual related cortex; (3) the intermediate zone, which does not receive fibers from the retina nor the visual cortex, is reciprocally connected with the midbrain, primarily with the superficial layers of the superior colliculus (SC), and gives rise to thalamic projections to the nucleus centralis lateralis bilaterally; and (4) the medial zone, from which commissural fibers arise, receives afferents bilaterally from the retina, and sends fibers to the SC bilaterally. These results suggest that the LGNv of the cat has three different zones. Functional participation of each zone has been discussed.
Higo
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Division of Morphological Neural Science, Department of Neuroscience and Immunology, Graduate School of Medical Sciences, Kumamoto University, Honjo 2-2-1 Kumamoto 860, Japan.
Kawamura
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D000818:Animals; D001370:Axonal Transport; D002415:Cats / Q000033:anatomy & histology*; D002772:Cholera Toxin; D007839:Functional Laterality; D005829:Geniculate Bodies / Q000033:anatomy & histology* / Q000166:cytology / Q000502:physiology*; D008959:Models, Neurological; D012160:Retina / Q000033:anatomy & histology / Q000502:physiology; D014793:Visual Cortex / Q000033:anatomy & histology / Q000502:physiology*; D014795:Visual Pathways / Q000502:physiology; D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
D018998:Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate; D002772:Cholera Toxin