Abnormal electrical brain responses to time deviance in beat deafness.

Humans have the spontaneous capacity to track the beat of music. Yet some individuals show marked difficulties. To investigate the neural correlates of this condition known as beat deafness, the cortical electric activity of ten beat-deaf adults, the largest cohort studied so far, as well as of 14 matched controls (Experiment 2), and 16 university students (Experiment 1) were examined. All were actively engaged in detecting anisochronous time-deviants in otherwise isochronous, metronome-like, sequences. As expected, participants with beat-deafness performed more poorly than controls; this behavioral impairment was accompanied by a reduced P300 component at the neurophysiological level, yet with intact N200. Additionally, the MMN following task-irrelevant intensity-deviants was not different between groups. Together the results suggest normal auditory predictions regarding upcoming tones but unreliable access to its representations. These results mirror the findings with pitch deviants in the pitch-based form of congenital amusia and provide a similar neural signature of the disorder on the pitch and time dimension.