Organization of visual inputs to the inferior temporal and posterior parietal cortex in macaques

Abstract

It has been proposed that visual information in the extrastriate cortex is conveyed along 2 major processing pathways, a “dorsal” pathway directed to the posterior parietal cortex, underlying spatial vision, and a “ventral” pathway directed to the inferior temporal cortex, underlying object vision. To determine the relative distributions of cells projecting to the 2 pathways, we injected the posterior parietal and inferior temporal cortex with different fluorescent tracers in 5 rhesus monkeys. The parietal injections included the ventral intraparietal (VIP) and lateral intraparietal (LIP) areas, and the temporal injections included the lateral portions of cytoarchitectonic areas TE and TEO. There was a remarkable segregation of cells projecting to the 2 systems. Inputs to the parietal cortex tended to arise either from areas that have been implicated in spatial or motion analysis or from peripheral field representations in the prestriate cortex. By contrast, inputs to the temporal cortex tended to arise from areas that have been implicated in form and color analysis or from central field representations. Cells projecting to the parietal cortex were found in visual area 2 (V2), but only in the far peripheral representations of both the upper and lower visual field. Likewise, labeled cells found in visual areas 3 (V3) and 4 (V4) were densest in their peripheral representations. Heavy accumulations of labeled cells were found in the dorsal parieto-occipital cortex, including the parieto-occipital (PO) area, part A of V3 (V3A), and the dorsal prelunate area (DP). In the superior temporal sulcus, cells were found within several motion-sensitive areas, including the middle temporal area (MT), the medial superior temporal area (MST), the fundus of the superior temporal area (FST), and the superior temporal polysensory area (STP), as well as within anterior portions of the sulcus whose organization is as yet poorly defined. Cells projecting to areas TE and TEO in the temporal cortex were located within cytoarchitectonic area TG at the temporal pole and cytoarchitectonic areas TF and TH on the parahippocampal gyrus, as well as in noninjected portions of area TE buried within the superior temporal sulcus. In the prestriate cortex, labeled cells were found in V2, V3, and V4, but, in contrast to the loci labeled after parietal injections, those labeled after temporal injections were concentrated in the foveal or central field representations. Although few double-labeled cells were seen, 2 regions containing intermingled parietal- and temporal-projection cells were area V4 and the cortex at the bottom of the anterior superior temporal sulcus.(ABSTRACT TRUNCATED AT 400 WORDS)

Frames of Reference for Perception and Action in the Human Visual System

“…These and other findings (for review, see (27)) suggest that visuomotor systems may be more sensitive to stimuli in the visual periphery than the perceptual systems mediating our experience of the visual world beyond the fovea. These behavioural observations in humans are consistent with anatomical and electrophysiological studies in the monkey showing that areas in the dorsal stream receive extensive inputs from the peripheral visual fields while inputs to the ventral stream are largely from more central regions of the visual field (for review, see (2,12)). The difference in representation of the visual field might explain why the visual control of grasping movements directed at targets in the visual periphery is so much more reliable than perceptual judgements about those same objects; in short, the dorsal action is simply better connected with the visual periphery than the ventral perception system.…”

Updating of the visual representation in monkey striate and extrastriate cortex during saccades

“…The density of projections decreases at earlier stages of the hierarchy, which parallels our observation of a reduced prevalence of remapping at earlier stages. Alternatively, remapping of visual signals may take place initially in parietal cortex and the remapping we observe in extrastriate cortex may reflect the influence of back projections from LIP (7)(8)(9).…”

“…Area V3A provides a major input to LIP and receives reciprocal projections from it (6)(7)(8)(9)(10). Area LIP is also reciprocally connected with the FEF (11,12).…”

Invariant Representations of Objects in Natural Scenes in the Temporal Cortex Visual Areas

“…Visual pathways project by a number of cortico-cortical stages from the primary visual cortex until they reach the temporal lobe visual cortical areas (Baizer et al 1991;Maunsell and Newsome 1987;Seltzer and Pandya 1978), in which some neurons that respond selectively to faces are found (Bruce et al 1981;Desimone 1991;Desimone and Gross 1979;Desimone et al 1984;Gross et al 1985;Perrett et al 1982;Rolls 1981Rolls , 1984Rolls , 1991Rolls , 1992aRolls , 2000aRolls , 2005Rolls , 2006Rolls and Deco 2002). The inferior temporal visual cortex, area TE, is divided on the basis of cytoarchitecture, myeloarchitecture, and afferent input into areas TEa, TEm, TE3, TE2, and TE1.…”