Target-selective tilt aftereffect during texture learning.

Sensory adaptation and perceptual learning are two forms of plasticity in the visual system, with some potential overlapping neural mechanisms and functional benefits. However, they have been largely considered in isolation. Here we examined whether extensive perceptual training with oriented textures (texture discrimination task, TDT) induces adaptation tilt aftereffects (TAE). Texture elements were oriented lines at -22.5° (target) and 22.5° (background). Observers were trained in 5 daily sessions on the TDT, with 800-1000trials/session. Thresholds increased within the daily sessions, showing within-session performance deterioration, but decreased between days, showing learning. To evaluate TAE, perceived vertical (0°) was measured prior to and after each daily session using a single line element. The results showed a TAE of ∼1.5° at retinal locations consistently stimulated by the target, but none at locations consistently stimulated by the background texture. Retinal locations equally stimulated by target and background elements showed a significant TAE (∼0.7°), in a direction expected by target-driven sensory adaptation. Moreover, these locations showed increasing TAE persistence with training. Additional experiments with a modified target, in order to have balanced stimulation around the vertical direction in all target locations, confirmed the locality of the task-dependent TAE. The present results support a strong link between perceptual learning and local orientation-selective adaptation leading to TAE; the latter was shown here to be task and experience dependent.