Decrease and increase in brain activity during visual perceptual priming: an fMRI study on similar but perceptually different complex visual scenes.
A robust finding among functional neuroimaging studies on visual priming is decreased neural activity in extrastriate and inferior prefrontal cortices for the second presentation of an object relative to its first presentation. This effect can also be observed for different but perceptually similar objects that are alternative exemplars of the initially presented object (e.g. two different pencils). An unanswered question is whether this decrease in activity can be found for the successive presentation of similar complex visual scenes. We used a test in which landscape pictures were divided vertically into three segments. A first segment was presented and followed several stimuli later by a second related segment. Reaction times were faster for the presentation of the second segment relative to the first one. Although perceptually different from the first segment, the presentation of the second segment was nonetheless associated with reduced activity in late stage visual processing areas including parahippocampal/fusiform gyri bilaterally, left middle occipital and temporal gyri, right inferior temporal and superior occipital gyri, and in left inferior frontal gyrus. The observed decreases in activity in these regions replicate results on priming of different exemplars of single objects while further extending these results to similar complex visual scenes. The presentation of the second segment was also associated with increased activity mainly in frontal and parietal regions, two areas known to be associated with memory retrieval. In sum, priming effects can also occur for complex visual scenes that are intrinsically different from each other although similar in their composition.