Does auditory discrimination training modify representations in both primary and secondary auditory cortex?

Several components of evoked auditory potentials and magnetic fields have been reported to be enhanced by musical training and by laboratory discrimination training. The P2 component, believed to originate in secondary auditory cortex (A2), is highly plastic, and enhanced both in trained musicians and by a variety of acoustic discrimination tasks. The 40-Hz auditory steady-state response (SSR) is believed to be generated in primary auditory cortex (A1). This response has been reported to be larger for trained musicians; however, in previous research SSR amplitude was not enhanced by laboratory training at pitch discrimination in non-musician adults. To explore whether competitive interactions among frequency representations in A1 may constrain remodeling, we designed a training procedure that provided subjects with experience of a single carrier frequency for 10 training sessions, alternating training and passive control blocks. P2 amplitude increased across sessions (p < 0.01) on passive as well as training blocks. SSR amplitude was larger in training compared to passive blocks (p < 0.01) and increased across sessions in both blocks (p < 0.01), giving the first evidence of acoustic remodeling in A1.