A Functional MRI Index of Spatial Context Effects in Vision

Coordination of brain activity, in the form of modulation of feedforward activity by stored information and expectations, occurs across domains of perception and cognition. A reliable and compelling example of this is size contrast in vision. This paper builds on a prior study to show that in healthy humans, the spread of activation in striate and extrastriate visual cortex during a context-modulated size perception task is dependent on the perceived size of the target image, not on the physical size of the retinal image. These data provide further evidence that early regions in visual cortex are modulated by top-down influences, and provide a framework for investigating visual context processing in psychiatric disorders where reduced sensitivity to visual contextual effects has been demonstrated in behavioral tasks.