Cortical thickness and reduced white matter – in a recent study, voxel-based morphometry, an imaging technique used to explore structural differences in the brain, revealed a decrease in white matter concentration in the right inferior frontal gyrus of amusic individuals as compared to controls. Lack of extensive exposure to music could be a contributing factor to this white matter reduction. For example, amusic individuals may be less inclined to listen to music than others, which could ultimately cause reduced myelination of connections to the frontal areas of the brain. Involvement of the parahippocampal gyrus (responsible for the emotional reaction to music)

Treatment
Currently, no forms of treatment have proven effective in treating amusia. One study has shown tone differentiation techniques to have some success; however, future research on treatment of this disorder will be necessary to verify this technique as an appropriate treatment. History
In 1825, F. Gall mentioned a "musical organ" in a specific region of the human brain that could be spared or disrupted after a traumatic event resulting in brain damage. In 1865, Jean-Baptiste Bouillaud described the first series of cases that involved the loss of music abilities that were due to brain injury. In 1878, Grant Allen was the first to describe in the medical literature what would later be termed congenital amusia, calling it "note-deafness". Later, during the late nineteenth century, several influential neurologists studied language in an attempt to construct a theory of cognition. While not studied as thoroughly as language, music and visual processing were also studied.
As a result of this defect in pitch perception, a lifelong musical impairment may emerge due to a failure to internalize musical scales. A lack of fine-grained pitch discrimination makes it extremely difficult for amusics to enjoy and appreciate music, which consists largely of small pitch changes.Tone-deaf people seem to be disabled only when it comes to music as they can fully interpret the prosody or intonation of human speech. Tone deafness has a strong negative correlation with belonging to societies with tonal languages. This could be evidence that the ability to reproduce and distinguish between notes may be a learned skill; conversely, it may suggest that the genetic predisposition towards accurate pitch discrimination may influence the linguistic development of a population towards tonality. A correlation between allele frequencies and linguistic typological features has been recently discovered, supporting the latter hypothesis.Tone deafness is also associated with other musical-specific impairments such as the inability to keep time with music (beat deafness, or the lack of rhythm), or the inability to remember or recognize a song. These disabilities can appear separately, but some research shows that they are more likely to appear in tone-deaf people. Experienced musicians, such as W. A. Mathieu, have addressed tone deafness in adults as correctable with training. Acquired amusia
Acquired amusia is a musical disability that shares the same characteristics as congenital amusia, but rather than being inherited, it is the result of brain damage. It is also more common than congenital amusia.