Neural Changes with Tactile Learning Reflect Decision-Level Reweighting of Perceptual Readout

• Type of Material: Article
• Authors: Krish Sathian, Emory University; Gopikrishna Deshpande, Auburn University; Randall Stilla, Emory University
• Language: English
• Date: 2013-03-20
• Publisher: Society for Neuroscience
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2013 the authors
• Final Published Version (URL): http://www.jneurosci.org/content/33/12/5387
• Title of Journal or Parent Work: Journal of Neuroscience Nursing
• ISSN: 0270-6474
• Volume: 33
• Issue: 12
• Start Page: 5387
• End Page: 5398
• Grant/Funding Information: Support to KS from the Veterans Administration is also gratefully acknowledged.; This work was supported by NIH grants R01EY12440 and K24EY17332 to KS.
• Research Categories: Psychology, General; Biology, Neuroscience

Abstract

Despite considerable work, the neural basis of perceptual learning remains uncertain. For visual learning, although some studies suggested that changes in early sensory representations are responsible, other studies point to decision-level reweighting of perceptual readout. These competing possibilities have not been examined in other sensory systems, investigating which could help resolve the issue. Here we report a study of human tactile microspatial learning in which participants achieved >six-fold decline in acuity threshold after multiple training sessions. Functional magnetic resonance imaging was carried out during performance of the tactile microspatial task and a control, tactile temporal task. Effective connectivity between relevant brain regions was estimated using multivariate, autoregressive models of hidden neuronal variables obtained by deconvolution of the hemodynamic response. Training-specific increases in task-selective activation assessed using the task-by-session interaction, and associated changes in effective connectivity, primarily involved subcortical and anterior neocortical regions implicated in motor and/or decision processes, rather than somatosensory cortical regions. A control group of participants tested twice, without intervening training, exhibited neither threshold improvement nor increases in task-selective activation. Our observations argue that neuroplasticity mediating perceptual learning occurs at the stage of perceptual readout by decision networks. This is consonant with the growing shift away from strictly modular conceptualization of the brain towards the idea that complex network interactions underlie even simple tasks. The convergence of our findings on tactile learning with recent studies of visual learning reconciles earlier discrepancies in the literature on perceptual learning.