Effects of perceptual learning on primary visual cortex activity in humans.

Psychophysical and neuroimaging studies suggest that perceptual learning may affect activity in primary visual cortex (V1). Yet, it remains unclear whether such changes involve intrinsic V1 plasticity or feedback from later processing stages. Here we recorded high-density electro-encephalography in 24 volunteers, 24-h after training on a visual texture discrimination task in the upper or lower visual-field. Post-training improvement in upper visual-field was associated with changes in early visual responses, starting 40ms post-stimulus, with reduced amplitude of retinotopic C1, known to reflect V1 activity. No behavioral or neurophysiological effect was found after training in lower visual-field, suggesting retinotopic constraints on perceptual learning. Our results demonstrate that successful acquisition of a perceptual skill can produce long-lasting changes for initial sensory inputs in the adult human visual system.