Melvyn A. Goodale, Ph.D., F.R.S.C.
Canada Research Professor in Visual Neuroscience
The University of Western Ontario
Visual Duplicity: Recent fMRI and Behavioral Evidence for Duplex Visual Processing for Perception and Action
Visual systems first evolved not to enable animals to see, but to provide distal sensory control of their movements. Vision as 'sight' is a relative newcomer on the evolutionary landscape, but its emergence has enabled animals to carry out complex cognitive operations on perceptual representations of the world. Behavioral and fMRI studies will be presented that provide evidence of separate processing for visuomotor control and perceptual representations. Converging lines of research suggest that these two functions of vision are mediated by separate cortical visual pathways arising from area V1 in the human cerebral cortex: a dorsal �action� pathway projecting to the posterior parietal cortex and a ventral �perception� pathway projecting to inferior temporal cortex. As the behavioral and fMRI studies indicate, these cortical pathways (which appear to be homologous with corresponding pathways in the monkey) make use of different metrics and different frames of reference in carrying out their computations. Both streams work together in the production of goal-directed behaviour.