Tone deafness: a model complex cortical phenotype

Abstract

-We all know people with tone deafness: these are the people who get thrown out of the choir at school. Although tone deafness is recognised as an output disorder, recent studies have characterised it as one of music perception in the absence of deafness or any associated cognitive disorder. The disorder can therefore be characterised as a form of auditory agnosia. This article considers how the phenotype might be deconstructed to the level of a causal deficit in the perception of pitch pattern. Based on our evolving understanding of the normal brain bases for this process a cortical deficit beyond primary cortex would be predicted. In tone deafness, structural cortical variations have been demonstrated by recent studies that detect subtle changes in the cortical mantle and underlying white matter: these changes are within a right hemisphere network for pitch pattern analysis and working memory for pitch. Studies of multiply affected families are underway to see if the disruption of this network can be caused by single genes. This disorder therefore offers the opportunity to study how a complex phenotype can be characterised as a cortical perceptual disorder potentially explained by a single gene or molecule. Although tone deafness is not pernicious, the underlying abnormality may prove to be a disorder of cortical connectivity that provides a model for disorders that are more so, such as schizophrenia.

Left temporal alpha band activity increases during working memory retention of pitches

“…Transcranial magnetic stimulation over the right hemispheric dorsolatero-frontal and inferior parietal regions was found to interfere with pitch memory in an N-back task (Imm et al, 2008). Additionally, studies of tone deafness show structural cortical variations within a right-hemispheric network for pitch pattern analysis and pitch memory (reviewed by Griffiths, 2008). Interestingly, as in our study, left hemispheric activity was also found to be involved in pitch memory using functional magnetic resonance imaging (Gaab & Schlaug, 2003).…”

“…, 2008). Additionally, studies of tone deafness show structural cortical variations within a right‐hemispheric network for pitch pattern analysis and pitch memory (reviewed by Griffiths, 2008). Interestingly, as in our study, left hemispheric activity was also found to be involved in pitch memory using functional magnetic resonance imaging (Gaab & Schlaug, 2003).…”

Speech perception, rapid temporal processing, and the left hemisphere: A case study of unilateral pure word deafness☆

“…His reported lifelong disinterest in music along with his poor performance on the MBEA raises the possibility that NL is a congenital amusic (i.e., was premorbidly “tone deaf”, see, e.g., Peretz, 2008). It may seem surprising that someone with amusia would perform so well on the consonance/dissonance detection task, however this does fit with recent proposals that congenital amusia may not reflect a deficit in pitch processing so much as a deficit in the detection of pitch direction or pitch patterns (Griffiths, 2008; Liu, Patel, Fourcin, & Stewart, 2010; Patel, 2008; Stewart, 2008). Alternatively, his ability to detect dissonance might result from non-pitch psychoacoustic differences between consonant and dissonant chords such as roughness (see, e.g., Vassilakis & Kendall, 2010).…”

Evaluation of musical skills in children with a diagnosis of an auditory processing disorder

“…The term ''congenital amusia'' refers to a developmental disorder characterised by abnormal perception of music in the presence of otherwise normal hearing and cognition [6]. This condition may be determined on a single gene basis, although a polygenic basis is still possible [7].…”