Friday, October 22, 2021

Ephrin A3, Tone Deafness, and Mental Health Concerns

 The joys of music is one of the greatest parts of our shared global culture. The impact that it has had not only socially by connecting people, but also mentally and psychologically is incredible as it’s used in various therapies and has methods of healing. We sing along to our favorite songs, attaching memories and emotions to the notes being played and the lyrics we listen to and though not all of us are musically inclined or talented, we’re still able to enjoy at least the listening aspect of music. 


There are those however who simply cannot experience music. Their auditory processing systems do not allow for them to differentiate tone or pitch which makes music sound entirely like a commotion of random sounds. This phenomenon is known as tone deafness, or amusia. Oftentimes when we hear about tone deafness, we’re teasing our friends seemingly can’t sing in tune, or are never able to hit a note in a song, or match basic pitch, however for true tone deafness, individuals are truly unable to differentiate in pitch and/or tone almost entirely. 


In the paper Ephrin-A3 is required for tonotopic map precision and auditory functions in the mouse auditory brainstem, Hoshio and Yu discuss the brain’s ability to differentiate between different tones and frequencies, and how Ephrin is one of the most important proteins that allows for this. However, in individuals that lack the ephrin-A3 gene, their research shows that, “[they] show a degraded tonotopic map, altered auditory activation patterns, and impaired detection of sound frequency changes. These results establish an essential role of ephrin-A3 in tonotopic map formation in the CN” (Yu et al. 2021). Initially, whilst reading this paper in particular I immediately thought about how this study could possibly relate to tone deafness, the perception of music, and possibly the connection to mental health conditions. Tone deafness, or amusia is most often genetic, however the neurological cause has not been specifically identified, studied, and proven, and while Hoshio and Yu’s research paper was not specifically aimed at discussing tone deafness, the discussion of the difficulties in making differentiations between sound frequencies establishes a significant connection to an area that has not been as widely studied. According to the paper The Genetics of Congenital Amusia (Tone Deafness): A Family-Aggregation Study, “Congenital amusia (commonly known as “tone deafness”) is a lifelong impairment of music perception that affects 4% of the population. Humans are born with the potential to both speak and make music.1 Thus, it is likely that musical capacity, like language capacity, is coded in the human genome. One powerful means to identify the relevant genes is to search for people who exhibit abnormal behaviors. In the speech domain, such conditions are often termed “specific language impairments” (SLI [MIM 606711]), and a large research effort has been undertaken to understand the origins and varieties of these disorders. This research recently made a major step forward with a rapid succession of discoveries that implicate specific genes as causative of abnormal language development3 (MIM 602081 and 605317). In the musical domain, there is no such comparable effort. Yet music-specific impairments have been reported” (Peretz, Cummings, Debe 2017)


The presence of music in an individual's life is also frequently tied to mediating mental health concerns such as anxiety and depression, as according to the article Reviewing the Effectiveness of Music Interventions in Treating Depression (Leubner, Hinterberger 2017), all participants in each studied age group of participants who listened to music fewer than five hours per week saw an improvement in their Depression Score Improvements upon listening to music more frequently, at least 7 hours per week. However, for those who experience tone deafness, they can experience the opposite with music being stress and anxiety inducing as the experience feels more like a ruckus and disturbance, rather than a method of comfort, therapy, or peace. 


In addition, it has been according to The Severity of Vestibular Dysfunction in Deafness as a Determinant of Comorbid Hyperactivity or Anxiety by Antoine, Vijayakumar, et al. 2017, discusses how tone deafness and/or other auditory processing disorders, such as possibly lacking an ephrin A3 gene causing a decreased precision in tonotopy, is more common in individuals who already experience mental conditions and disorders such as attention deficit disorder (ADD), attention deficit hyperactive disorders (ADHD), as well as autism spectrum disorder (ASD), amongst others. These groups of people also are more prone to generalised anxiety and social anxiety as well as depression. 


I believe that expanding on the topic the Hoshio and Yu studied with auditory processing and the lack in precision of tonotopy for certain individuals, regardless of the cause, would be widely beneficial to connect to the field of psychiatry as there seem to be multiple levels of connections that simply have not be widely studied, but if studied could contribute greatly to the greater scientific and medical communities. 


References

Antoine, Michelle W., et al. “The Severity of Vestibular Dysfunction in Deafness as a Determinant of Comorbid Hyperactivity or Anxiety.” Journal of Neuroscience, Society for Neuroscience, 17 May 2017, https://www.jneurosci.org/content/37/20/5144?utm_source=TrendMD&utm_medium=cpc&utm_campaign=JNeurosci_TrendMD_1.

Hoshino N;Altarshan Y;Alzein A;Fernando AM;Nguyen HT;Majewski EF;Chen VC;Rochlin MW;Yu WM; “Ephrin-A3 Is Required for Tonotopic Map Precision and Auditory Functions in the Mouse Auditory Brainstem.” The Journal of Comparative Neurology, U.S. National Library of Medicine, https://pubmed.ncbi.nlm.nih.gov/34235739/.

Leubner, Daniel, and Thilo Hinterberger. “Reviewing the Effectiveness of Music Interventions in Treating Depression.” Frontiers in Psychology, Frontiers Media S.A., 7 July 2017, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5500733/.

Peretz, Isabelle, et al. “The Genetics of Congenital Amusia (Tone Deafness): A Family-Aggregation Study.” American Journal of Human Genetics, The American Society of Human Genetics, Sept. 2017, https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1950825/. 


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