Abstract
Although practice is known to improve perceptual discrimination of basic visual features, such as small differences in the orientation of line patterns, the neural basis of this improvement is less well understood. Here, we used functional MRI in combination with pattern-based analyses to probe the neural concomitants of perceptual learning. Subjects extensively practiced discriminating small differences in the orientation of a peripherally presented grating. Training occurred in daily 1-hour sessions across 20 days, during which subjects performed the task based on a single orientation at a single location in the visual field. BOLD activity was measured before and after training, while subjects performed the orientation discrimination task on the trained orientation and location, as well as three other orientations and a second isoeccentric location. Behavioral thresholds showed large improvements in performance after training, with a 40% mean reduction in thresholds for the trained orientation at the trained location, and no significant improvement for any of the other conditions. However, analysis of the amplitude of the BOLD response did not reveal a location- or orientation-specific change in gross activity in early visual areas. To test whether learning nonetheless improved the representation of the trained orientation at the trained location, we used a pattern-based analysis to decode the presented stimulus orientation from cortical activity in these regions. Preliminary analyses indicated better decoding performance in areas V1 and V2 for the trained orientation and location, as compared to the untrained conditions. These results suggest that, when analyzed at the population level, perceptual learning results in an improved early-level representation at the trained location for the trained visual feature.
This work was supported by a Rubicon grant from the Netherlands Organization for Scientific Research (NWO) to J.J., NRSA grant F32 EY019802 to S.L., NRSA grant F32 EY019448 to J.S., NEI grant R01 EY017082 to F.T., and NEI center grant P30 EY008126.