%0 Journal Article
%T Neural Pathways Conveying Novisual Information to the Visual Cortex
%A Wen Qin
%A Chunshui Yu
%J Neural Plasticity
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/864920
%X The visual cortex has been traditionally considered as a stimulus-driven, unimodal system with a hierarchical organization. However, recent animal and human studies have shown that the visual cortex responds to non-visual stimuli, especially in individuals with visual deprivation congenitally, indicating the supramodal nature of the functional representation in the visual cortex. To understand the neural substrates of the cross-modal processing of the non-visual signals in the visual cortex, we firstly showed the supramodal nature of the visual cortex. We then reviewed how the nonvisual signals reach the visual cortex. Moreover, we discussed if these non-visual pathways are reshaped by early visual deprivation. Finally, the open question about the nature (stimulus-driven or top-down) of non-visual signals is also discussed. 1. Introduction The visual cortex has been traditionally considered as a stimulus-driven, unimodal system with a hierarchical organization, in which the early visual areas (V1, V2) tune to general features while the higher-tier ones (V3A, V4v, V7, hMT+, and V8) respond selectively to the specific features of a visual stimulus [1每5]. Two parallel visual streams have been proposed to generalize the hierarchical organization of the visual processing [6每8]. The dorsal stream or ※where§ pathway serves to analyze visual spatial information about object location, motion, and visuomotor planning. In this pathway, visual signals are conveyed to the posterior parietal cortex through the dorsal part of the visual cortex (such as the V3d, V3A, V7, and hMT+) and finally reach the prefrontal cortex. The ventral stream or ※what§ pathway has been associated with the processing of form, object identity, and color. This pathway conveys visual signals along the ventral part of visual cortex (such as VP, V4, and V8), the inferior temporal (IT) areas, and finally to the prefrontal cortex. The structural and functional organization of the visual areas is supposed to develop through a combination of genetic instruction [9每11] and experience-dependent refinement [12, 13]. The role of visual experience in the development of the visual areas is supported by a large number of neuroimaging studies revealing that the visual areas of congenitally blind (CB) and early blind (EB) subjects have increased cortical thickness [14每17], local brain spontaneous activity [18], metabolism, and blood flow [19每22] and decreased regional volume [23每25], white matter integrity [26, 27], anatomical network efficiency [28, 29], and altered resting-state functional connectivity
%U http://www.hindawi.com/journals/np/2013/864920/