Investigating the effects of perceptual learning on the function and microstructure of the visual cortex

Abstract

Perceptual learning is the long-term improvement of the ability to process sensory stimuli through experience. Although an extensively studied field, the mechanism and locus of plasticity underlying visual perceptual learning is subject of debate. Here, we investigated the experience-dependent plasticity in the visual cortex across the time course of perceptual learning of bisection discrimination task. Population receptive field (pRF) analysis was used to examine functional architecture of the visual cortex. Microstructural properties of the visual cortex were characterized with neurite orientation dispersion and density imaging (NODDI). We compared pre-, mid-, and post-training values of pRF size, neurite density, and orientation dispersion in the trained location as well as in two control locations where no training has been received. The values in the trained location did not change with time and did not differ from control locations. In addition, we assessed the microstructural properties in the white matter tract between the training location and the mirror-symmetric control location and did not observe any change with training. In conclusion, we found no training-related changes in the early visual cortex (V1-V3). Our results are limited by the lack of performance improvement with training and the small sample size. Moreover, we were not able to identify visual areas beyond V1-V3 leaving high-level visual areas unexplored. Suggestions for further research include redesigning the behavioral training paradigm, optimization of pRF protocol to identify high-level visual areas, and repeating the study with a larger sample size.