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Poster C75, Thursday, November 9, 10:00 – 11:15 am, Harborview and Loch Raven Ballrooms

Early Sensory Changes in Neural Processing Gate Generalized Perceptual Learning

Shannon Heald1, Sophia Uddin1, Stephen Van Hedger1, Joel Snyder2, Howard Nusbaum1;1The University of Chicago, 2University of Nevada, Las Vegas

The ability to generalize beyond a series of experiences is an important aspect of learning. This ability may underlie robust recognition of spoken words despite a wide range of acoustic-pattern variability, noise, and distortion in the listening environment. While there is evidence that generalized learning from training results in changes in central auditory processing, the time course and nature of these changes is unclear. To assess how generalized learning rapidly alters central auditory processing, we measured auditory evoked potentials (AEPs) while listeners engaged in a generalized synthetic speech learning task. Listeners were tested and trained on synthetic speech (Rsynth, a Klatt based synthesizer) generated by rule, containing degraded and sometimes misleading acoustic cues. Training consisted of identification of single spoken words followed by a paired presentation of the spoken word with its printed form. We measured single word AEPs to 100 words at pretest before training and to 100 words at posttest after training with 128 electrodes (EGI system). Testing consisted of word identification without feedback. As a consequence of training, listeners’ recognition of hard-to-understand synthetic speech rapidly improved, even though no words repeated across tests or training, indicating successful generalized learning. Analysis of changes in the AEPs from pretest to posttest revealed both short-latency and long-latency changes concomitant with generalized learning. The degree of behavioral improvement was significantly related to long-latency brain electrical responses (~584 ms to 784 ms) in posttest AEPs. However, a multiple mediation analysis revealed that early AEP components (during the N1 and P2 period), that reflect changes in auditory cortex, mediated this association. These results suggest that generalized learning can quickly alter central auditory processing and that such changes, which reflect an adjustment of attention and refinement of auditory representations, appear to mediate changes in later stages of processing.

Topic Area: Perception: Speech Perception and Audiovisual Integration

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