Abstract
Visual perceptual learning (VPL) is long-term visual performance improvement after visual experiences. Which stage of visual processing is changed in association with VPL is one of the most serious controversies in the field. The low-level model of VPL attributes VPL to changes only in visual areas. The higher-level cognitive model attributes VPL to changes in decision-related areas or in connectivity between visual and decision-related areas. Here we show the evidence that supports a two-stage model in which VPL is associated with the changes in both visual and decision-related areas that reflect different aspects of plasticity. Thirteen human subjects participated in a 10-day training on a global motion detection task for a certain motion direction (trained direction). After training, the subjects’ performance significantly improved specifically for the trained direction, but not for an untrained direction. Before and after training, we measured subjects’ functional magnetic resonance imaging (fMRI) signals in relevant motion condition and irrelevant motion condition. In the relevant motion condition, the subjects engaged in the same task as in training. In the irrelevant motion condition, the subjects were asked to perform a letter detection task while the same motion stimulus as in the training was presented in the background as task-irrelevant. A pattern-classification analysis revealed that visual area V3A, which has been implicated in VPL of global motion in some studies, showed significant response changes to the trained motion direction in both conditions. On the other hand, intraparietal sulcus (IPS), which is regarded as decision-related and has also been implicated in VPL of motion in other studies, showed significant response changes to the trained direction only in the relevant motion condition. These results indicate that VPL of global motion results from two different types of plasticity at different stages, feature-specific plasticity and task-specific plasticity, and may resolve the long-standing controversy.
Meeting abstract presented at VSS 2013