Connections of visual areas of the upper temporal lobe of owl monkeys: the MT crescent and dorsal and ventral subdivisions of FST.
An oval of cortex of moderately dense myelination just ventral to the middle temporal visual area (MT) with input from MT has been referred to as the fundal area of the superior temporal sulcus (FST). Injections of the tracer WGA-HRP into dorsal (FSTD) and ventral (FSTv) halves of FST revealed that only FSTD has connections with MT. FSTv has connections instead with small patches of cortex that string together like beads to form a ring or crescent (MTc) around most of MT. The patches in MTc stain densely for myelin or cytochrome oxidase, and they are embedded in a less densely stained matrix. The connections of FSTD associate the area with the dorsal stream of processing directed toward posterior parietal cortex and important in spatial aspects of vision. Thus, FSTD has direct connections with ventral posterior parietal cortex (VPP), and connections with MT, the medial superior temporal (MST), and dorsomedial (DM) visual areas, all areas that relay to posterior parietal cortex. In contrast, FSTv does not appear to have connections with either VPP or MST, and only sparse connections with DM. Rather, major connections of FSTv are with inferior temporal cortex. Thus, FSTv is more associated with the ventral stream of processing related to object vision. However, both FSTv and FSTD have connections with area 18 or V-II, the dorsolateral visual area, the frontal eye field, and a frontal visual area. Interhemispheric connections of FSTD include FSTD, MT, and MST, while interhemispheric connections of FSTv include FSTv and MTc.
Department of Psychology, Vanderbilt University, Nashville, Tennessee 37240.
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Kaas
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D000818:Animals; D016645:Aotidae / Q000033:anatomy & histology*; D003576:Electron Transport Complex IV / Q000032:analysis; D006735:Horseradish Peroxidase; D009185:Myelin Proteins / Q000032:analysis; D009186:Myelin Sheath / Q000502:physiology; D009434:Neural Pathways / Q000033:anatomy & histology; D013702:Temporal Lobe / Q000033:anatomy & histology*; D014785:Vision, Ocular; D014793:Visual Cortex / Q000033:anatomy & histology*; D014909:Wheat Germ Agglutinins
D009185:Myelin Proteins; D014909:Wheat Germ Agglutinins; D006735:Horseradish Peroxidase; D003576:Electron Transport Complex IV