Poster #: 83
Topic: MMN across species
Thursday, Sep 10, 2015
Passive exposure to speech sound features enhances cortical plasticity revealed by mismatch response in rats
1Department of psychology, University of Jyväskylä, Jyväskylä, Finland
2Department of Psychology, University of Jyväskylä, Jyväskylä, Finland
Speech sound perception is not static but rather is modified by experience, thus enabling adaption to new situations. An ability to discriminate speech sound features is not unique to humans but exist for example in rodents. Passive exposure to sinusoidal sounds can improve rat’s behavioral discrimination ability. However, there is no electrophysiological evidence on impact of passive exposure to brain plasticity. Mismatch negativity (MMN) response is a feasible tool to probe auditory perceptual learning in humans and it can elicited in rats too. Here we passively exposed two groups of animals to speech sound features for 12 hours per day for three consecutive days. Animals were exposed either to duration changes, or tonal changes in vowel /a/ presented in oddball condition. After the exposure we recorded auditory evoked potentials on the auditory cortex by electrocorticogram (ECoG). The group of animals that was exposed to duration changes had enhanced amplitudes of mismatch response compared to naïve rats. While mismatch response was elicited in both trained and naïve groups for the 100-ms deviant sound (standard 200ms), only trained animals showed mismatch response for the 150-ms deviant sound. Exposure to tonal changes had no observable effect on LFPs. The result suggest that passive exposure to duration changes in speech sounds results in plastic changes in primary auditory cortex in adult rats.