Tune deafness: processing melodic errors outside of conscious awareness as reflected by components of the auditory ERP.
Tune deafness (TD) is a central auditory processing disorder characterized by the inability to discriminate pitch, reproduce melodies or to recognize deviations in melodic structure, in spite of normal hearing. The cause of the disorder is unknown. To identify a pathophysiological marker, we ascertained a group of severely affected TD patients using the Distorted Tunes Test, an ecologically valid task with a longstanding history, and used electrophysiological methods to characterize the brain's responses to correct and incorrect melodic sequences. As expected, we identified a neural correlate of patients' unawareness of melodic distortions: deviant notes modulated long-latency auditory evoked potentials and elicited a mismatch negativity in controls but not in affected subjects. However a robust P300 was elicited by deviant notes, suggesting that, as in blindsight, TD subjects process stimuli that they cannot consciously perceive. Given the high heritability of TD, these patients may make it possible to use genetic methods to study cellular and molecular mechanisms underlying conscious awareness.
Braun
Allen
A
Language Section, National Institute on Deafness and Other Communication Disorders, National Institutes of Health, Bethesda, Maryland, United States of America. brauna@nidcd.nih.gov
McArdle
Joe
J
Jones
Jennifer
J
Nechaev
Vladimir
V
Zalewski
Christopher
C
Brewer
Carmen
C
Drayna
Dennis
D
D001364:Awareness; D005072:Evoked Potentials, Auditory; D006801:Humans; D007805:Language Development Disorders / Q000503:physiopathology*; D009146:Music