Causal Mechanisms Driving Visual Cortical Plasticity and Perceptual Learning in Primates
42 Pages Posted: 11 Apr 2018 Publication Status: Review Complete
More...Abstract
Practice improves perception and enhances neural representations of trained stimuli, a phenomenon known as visual perceptual learning (VPL). While selective attention was considered necessary for such learning, mere Pavlovian association of a stimulus with a reinforcer is sufficient to drive VPL, even unconsciously. This finding adds support to neuromodulatory theories of VPL, which posit that reinforcement facilitates learning through the activation of neuromodulatory centers. We causally tested these theories by pairing unattended visual stimuli with microstimulation of a dopaminergic center, the ventral tegmental area (VTA), and examined its effect on cortical responses and perceptual abilities. Pairing VTA microstimulation with a visual stimulus increased fMRI activity and improved classification of fMRI activity patterns selectively for the microstimulation-paired stimulus. Moreover, pairing VTA microstimulation with a visual stimulus improved the subject’s capacity to discriminate that stimulus. These findings causally demonstrate the role of neuromodulatory centers in VPL and associated cortical plasticity in primates.
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