Top-Down Cortical Influences in Visual Expectation

Visual perception depends on prior experience. Previous encounters with visual objects allow an organism to form expectations about future encounters, and to use those expectations to tune the visual system to more efficiently process expected visual inputs. This paper explores the proposition that visual expectation involves top-down modulation of neurons in low-level areas of visual cortex in anticipation of expected stimuli. It reports evidence that top-down modulation occurs within task-specific coherent oscillatory networks in the visual cortex of a macaque monkey, and that this modulation is related to stimulus processing efficiency.