Behavioral/Systems/Cognitive A Link between Visual Disambiguation and Visual Memory

Sensory information in the retinal image is typically too ambiguous to support visual object recognition by itself. Theories of visual disambiguation posit that to disambiguate, and thus interpret, the incoming images, the visual system must integrate the sensory informationwith previous knowledge of the visual world. However, the underlying neuralmechanisms remain unclear. Using functional magnetic resonance imaging (fMRI) of human subjects, we have found evidence for functional specialization for storing disambiguating information in memory versus interpreting incoming ambiguous images. Subjects viewed two-tone, “Mooney ” images, which are typi-cally ambiguous when seen for the first time but are quickly disambiguated after viewing the corresponding unambiguous color images. Activity in one set of regions, including a region in the medial parietal cortex previously reported to play a key role in Mooney image disambiguation, closely reflectedmemory for previously seen color images but not the subsequent disambiguation ofMooney images. A second set of regions, including the superior temporal sulcus, showed the opposite pattern, in that their responses closely reflected the subjects ’ percepts of the disambiguatedMooney images on a stimulus-to-stimulus basis but not thememory of the corresponding color images. Functional connectivity between the two sets of regionswas stronger during those trials in which the disambiguated percept was stronger. This functional interaction between brain regions that specialize in storing disambiguating information in memory versus interpreting incoming ambiguous images may represent a general mechanism by which previous knowledge disambiguates visual sensory information