The influence of short term perceptual learning of pitch discrimination and modulation discrimination on subcortical envelope-following and cortical steady-state EEG responses

Abstract

Many perceptual skills improve with training, and research suggests that long- and short-term experiences modify auditory neural structures and function. Long-term cortical and subcortical plasticity has been associated with musical training and fluency in tonal languages, and short-term training effects have been regularly observed in cortical responses. Less is known about short-term subcortical plasticity, or the simultaneous relationships between subcortical and cortical responses under training conditions. The current study examines short-term learning and neural plasticity, using behavioral measures in combination with simultaneous subcortical and cortical steady-state EEG responses. Untrained, naive subjects were randomly assigned to groups that were trained on fundamental-frequency (F0) discrimination, amplitude-modulation rate discrimination, or visual orientation discrimination. All auditory stimuli consisted of unresolved harmonic complexes with a nominal F0 of 137 Hz that were sinusoidally amplitude modulated at 100% depth and 13-Hz rate. Simultaneous subcortical envelope-following responses (EFR) to the F0 and cortical auditory steady-state responses (ASSR) to the modulation rate were measured pre- and post-training, and changes in the magnitude of phase locking to the respective frequency components were compared to changes in behavioral measures. The methods provide a new window on subcortical and cortical plasticity and their interactions. [Work supported by NIH grant R01DC05216.]