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Rufin Vogels; Learning to discriminate simple stimuli modifies the response properties of early and late visual cortical areas. Journal of Vision 2015;15(12):1419. doi: 10.1167/15.12.1419.
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© ARVO (1962-2015); The Authors (2016-present)
Practicing simple visual detection and discrimination tasks improves performance, a signature of adult brain plasticity. Current models of learning with simple stimuli such as gratings postulate either changes in early visual cortex or reweighting of stable early sensory responses at the decision stage. We showed that practice in orientation discrimination of noisy gratings (coarse orientation discrimination) increased the ability of single neurons of macaque visual area V4 to discriminate the trained stimuli. Then we asked whether practice in the same task also changes the response properties of later visual cortical areas. To identify candidate areas, we used fMRI to map activations to noisy gratings in the trained monkeys, revealing a region in the posterior inferior temporal (PIT) cortex. Subsequent single unit recordings showed that the PIT neurons discriminated better the trained compared with the untrained orientations, even when the animals were performing an orthogonal task. Unlike in previous single unit studies of learning in early visual cortex, more PIT neurons preferred trained compared with untrained orientations. Thus, practicing a simple discrimination of grating stimuli cannot only affect early visual cortex but also changes the response properties of late visual cortical areas. Perturbation of the activity in PIT reduced the coarse orientation discrimination performance in the trained animals, suggesting that this region is indeed part of the network underlying the performance in the task. We suggest that visual learning modifies the responses of most if not all areas that are part of the cortical network which supports the task execution.
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