Perfect Pitch

By Shriya Manwani

Perfect pitch, also referred to as absolute pitch, is the ability to identify the pitch of musical notes without a reference note and mentally classify the sounds into categories that can be recreated from memory. The prevalence of this musical ability is low with less than 1 person in every 10,000 report possessing this ability,, and no significant difference between genders. Expert musicians such as Mozart, Bach and Beethoven, who had early musical training and spent thousands of hours practicing had perfect pitch. However, many other equally prominent musicians with the same amount of musical training, such as Wagner and Schumann, lacked it. The fact that most individuals with early musical training do not develop perfect pitch suggests that environmental factors, in the form of early musical training, is necessary but not sufficient for the development of perfect pitch.

Previous research draws a correlation between environmental influences, in the form of very early and extensive musical training, and the likelihood of perfect pitch development. Such studies suggest that exposure to musical training during the critical period of auditory development – at the age of 6 or younger – contributes to the genesis of perfect pitch. During such periods, neural circuits are amenable to the establishment of new circuits or the fine-tuning of pre-existing circuits involved in pitch perception in the presence of sensory stimuli. Interestingly, this is especially true for speakers of tonal languages – languages in which words differ in tones in addition to consonants and vowels, such as Mandarin, Vietnamese, Thai and Punjabi. This critical period for the development of perfect pitch may overlap the period during which speech perception specialises to sounds of their native language in children.

There is also strong evidence that suggests a genetic influence on the development of perfect pitch. It is thought to be associated with many morphological changes in the brain, however the fundamental neural mechanisms are not yet clear. Psychophysical and physiological experiments suggest that high-level cortical processes, such as speaking, writing and reading, are involved in pitch perception. Positron-emission-tomography studies of musicians with and without perfect pitch show anatomical asymmetry of the planum temporale (an auditory area of the brain) as well as differences in cortical thickness and connectivity in these regions, which may be involved in the processing of pitch perception.  Compared with controls, increased activation in the left superior temporal sulcus has been observed in perfect pitch musicians during a pitch memory task. Increased functional activations in the superior temporal gyrus, bilateral Heschl’s gyrus and middle temporal gyrus during a music-listening task was also observed. A strong concordance of the perfect pitch phenotype is observed in families for which two or more first-degree relatives had perfect pitch. In these families, the inheritance pattern of perfect pitch is an autosomal dominant trait, however with incomplete penetrance which may be explained by lack of early musical training in some families.

A study was performed by Theusch, E., et al in 2009 in which a genome-wide linkage study on 73 multiplex perfect pitch families was performed by genotyping them with 6090 SNP markers, in order to identify regions of the human genome that may contain perfect pitch-predisposing genetic variants. After conducting nonparametric multipoint linkage analyses, the strongest evidence for linkage was observed on chromosome 8q24.21. Other regions with suggestive chromosomes included chromosomes 7q22.3, 8q21.11, and 9p21.3. Though only chromosome 8q24.21 reached statistical significance, several other regions showed independent linkage peaks. It may be possible that, apart from only one genetic variant required to predispose individuals to developing perfect pitch, gene-gene interactions could also lead to its development. These findings suggest that multiple regions of the genome harbor perfect pitch-predisposing variants, which therefore indicates that AP is genetically heterogeneous.

Interpretation of existing literature on perfect pitch is difficult due to the variation in how it has been operationally defined and tested. For example, some investigators have interpreted perfect pitch possessors to be capable of producing specific tones without a reference note, whereas others have focused only on the ability to recognize a pitch. Limited number of studies performed, as well as previous studies conducted with small sample sizes, make the evaluation of evidence for both genetic and nongenetic factors on perfect pitch difficult. However, the few studies that have been performed suggest that, apart from environmental influences, there is also a genetic contribution to the development of the phenotype. 

References:

Acoustical Society of America (ASA). (2012) Perfect pitch: Knowing the note may be in your genes. Available from: https://www.sciencedaily.com/releases/2012/10/121023124000.htm [Date of access:  27th September 2020]

Baharloo, S., Johnston, P. A., Service, S. K., Gitschier, J. & Freimer, N. B. (1998) Absolute Pitch: An Approach for Identification of Genetic and Nongenetic Components. American Journal of Human Genetics. 62 (2), 224-231. Available from: http://dx.doi.org/10.1086/301704. Available from: doi: 10.1086/301704.

Benjamin K. Dichter, Jonathan D. Breshears, Matthew K. Leonard, Edward F. Chang. (2018) The Control of Vocal Pitch in Human Laryngeal Motor Cortex. Cell. 174 (1), 21. Available from: doi: 10.1016/j.cell.2018.05.016

Larissa McKetton, Kevin DeSimone and Keith A. Schneider (2019) Larger auditory cortical area and broader frequency tuning underlie absolute pitch. Journal of Neuroscience. Available from: doi: 10.1523/JNEUROSCI.1532-18.2019

Theusch, E., Basu, A. & Gitschier, J. (2009) Genome-wide Study of Families with Absolute Pitch Reveals Linkage to 8q24.21 and Locus Heterogeneity. American Journal of Human Genetics. 85 (1), 112-119. Available from: http://dx.doi.org/10.1016/j.ajhg.2009.06.010. Available from: doi: 10.1016/j.ajhg.2009.06.010.

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