Superior formation of cortical memory traces for melodic patterns in musicians

Abstract

The human central auditory system has a remarkable ability to establish memory traces for invariant features in the acoustic environment despite continual acoustic variations in the sounds heard. By recording the memory-related mismatch negativity (MMN) component of the auditory electric and magnetic brain responses as well as behavioral performance, we investigated how subjects learn to discriminate changes in a melodic pattern presented at several frequency levels. In addition, we explored whether musical expertise facilitates this learning. Our data show that especially musicians who perform music primarily without a score learn easily to detect contour changes in a melodic pattern presented at variable frequency levels. After learning, their auditory cortex detects these changes even when their attention is directed away from the sounds. The present results thus show that, after perceptual learning during attentive listening has taken place, changes in a highly complex auditory pattern can be detected automatically by the human auditory cortex and, further, that this process is facilitated by musical expertise.

Figure 1

(Upper panel) Schematic illustration of the melodic patterns used in the present study. The arrow indicates the change in melodic pattern in infrequently presented deviant patterns. (Lower panel) Event-related potentials elicited by the standard (90%; thin line) and the deviant (10%; thick line) melodic patterns recorded at the Fz electrode. In the Accurate subjects, an MMN was elicited during the second and third Ignore conditions following the first Attend condition (right column). In the Inaccurate subjects, no MMN was observed at any phase of the experiment despite intermediate Attend conditions (left column).

Figure 2

Average locations of the magnetic MMN responses (left: 3 Ss, right: 2 Ss) as modeled by the equivalent current source dipoles superimposed on a magnetic resonance imaging scan of one subject.