Magnetic stimulation of visual cortex impairs perceptual learning

- We used rTMS to examine the causal role of V2d/V3 and LO in perceptual learning.
- Interference with visual areas increased reaction times to learned stimuli.
- Stimulation of parietal region (IPS) did not affect behavioral performance.
- rTMS effect over the two visual regions was positive correlated.
- Visual network causally and topographically contributes to perceptual learning.

The ability to learn and process visual stimuli more efficiently is important for survival. Previous neuroimaging studies have shown that perceptual learning on a shape identification task differently modulates activity in both frontal-parietal cortical regions and visual cortex (Sigman et al., 2005; Lewis et al., 2009). Specifically, fronto-parietal regions (i.e. intra parietal sulcus, pIPS) became less activated for trained as compared to untrained stimuli, while visual regions (i.e. V2d/V3 and LO) exhibited higher activation for familiar shape. Here, after the intensive training, we employed transcranial magnetic stimulation over both visual occipital and parietal regions, previously shown to be modulated, to investigate their causal role in learning the shape identification task. We report that interference with V2d/V3 and LO increased reaction times to learned stimuli as compared to pIPS and Sham control condition. Moreover, the impairment observed after stimulation over the two visual regions was positive correlated. These results strongly support the causal role of the visual network in the control of the perceptual learning.