Brain mechanisms of visual form perception
In primates, the perception of complex visual patterns emerges from neuronal activity in a cascade of areas in the cerebral cortex. Neurons in the primary visual cortex, V1, represent information about the local orientation and scale of image elements, but in the next downstream area, V2, cells respond more vigorously to stimuli containing naturalistic statistical structure than to matched control stimuli without that structure. Downstream of V2 the representation of natural scenes and objects becomes a more prominent driving feature of cortex. Humans show BOLD fMRI responses that are consistent with neuronal measurements in macaque. These results can be explained in terms of a feedforward cascade of information processing. They suggest how information about elementary visual features is transformed into the specific representations of scenes and objects found in areas downstream in the visual pathway.