Visual association pathways in human brain.

Visual information processing are realized by the posterior association cortex spreading in front of the striate and parastriate areas from which two major visual association pathways arise. The dorsal or the occipito-parietal pathway which transmits the inputs from the peripheral as well as the central visual field to the parietal association cortex is responsible for the visuospatial analysis of the visual informations. The occipito-temporal or the ventral pathway originates only from the foveal vision area, and sends the visual inputs to the inferior temporal lobe which engages in visual pattern or whole gestalt recognition of the visual informations. In addition to this dichotomous disposition of the dorsal and the ventral visual association pathways in each cerebral hemisphere, there is another type of functional specialization which is hierarchical rather than dichotomous. In the left cerebral hemisphere, the collateral pathways arise from both dorsal and ventral main streams and engage in the process of reading, or the verbal mode of visual information processing.