How the brain learns to see objects and faces in an impoverished context

A degraded image of an object or face, which appearsmeaningless when seen for the first time, is easily recognizableafter viewing an undegraded version of the same image. The neural mechanisms by whichthis form of rapid perceptual learning facilitates perception are notwell understood. Psychological theory suggests the involvementof systems for processing stimulus attributes, spatial attentionand feature binding,as well as those involved in visual imagery. Here we investigate where andhow this rapid perceptual learning is expressed in the human brain byusing functional neuroimaging to measure brain activity duringexposure to degraded images before and after exposure to thecorresponding undegraded versions (Fig. 1). Perceptuallearning of faces or objects enhanced the activity of inferiortemporal regions known to be involved in face and object recognitionrespectively. In addition, both faceand object learning led to increased activity in medial and lateralparietal regions that have been implicated in attention and visual imagery. We observed a strong couplingbetween the temporal face area and the medial parietal cortexwhen, and only when, faces were perceived. Thissuggests that perceptual learning involves direct interactions betweenareas involved in face recognition and those involved in spatialattention, feature binding and memoryrecall.