Functional MRI Evidence of an Abnormal Neural Network for Pitch Processing in Congenital Amusia

Abstract

Congenital amusia (tone deafness) is a lifelong disorder that prevents typically developing individuals from acquiring basic musical skills. Electrophysiological evidence indicates that congenital amusia is related to a musical pitch deficit that does not seem to arise from a dysfunction of the auditory cortex but rather from an anomaly along a frontotemporal auditory pathway. In order to better localize the neural basis of this pitch disorder, here we conducted a functional magnetic resonance imaging (fMRI) study. Congenital amusic adults and "musically intact" controls were scanned while passively listening to pure-tone melodic-like sequences in which the pitch distance between consecutive tones was varied parametrically. In both amusics and controls, brain activity increased as a function of increasing pitch distance, even for fine pitch changes, in both the left and right auditory cortices. These results support prior electrophysiological work showing that the auditory cortex of amusic individuals responds normally to pitch. In contrast, the right inferior frontal gyrus showed an abnormal deactivation in the amusic group, as well as reduced connectivity with the auditory cortex as compared with controls. These fMRI data are highly consistent with previous gray and white matter anomalies found in amusics in the auditory and inferior frontal cortices, as well as reduced white matter connections between these 2 regions.

Reduced sensitivity to emotional prosody in congenital amusia rekindles the musical protolanguage hypothesis

“…Third, evidence suggests that the same acoustic cues are used in music and speech prosody to convey the same emotional messages (1), and researchers have argued that emotional signals in the two domains are decoded using shared brain circuitry (2, 3, 12). Fourth, recent neuroimaging studies indicate that the amusic brain can be described by anomalies of the right hemisphere (50,51), which has also been found to be crucial for emotional-speech-prosody processing in healthy brains (52). For example, neuroimaging studies suggest that the right mid-superior temporal gyrus adjacent to the superior temporal sulcus plays an important role in the processing of emotional prosody (52)(53)(54)(55)(56).…”

Impaired Explicit Processing of Musical Syntax and Tonality in a Group of Mandarin-Speaking Congenital Amusics

“…Taken together, the impaired explicit processing of musical syntax and tonality may be attributed not only to a neural anomaly underlying processing of pitch, such as abnormal N2 elicited by an unexpected out-of-key tones in a melodic context (Peretz et al, 2009) and the absence of P3b indexing inability to perceive small pitch changes (Moreau, Jolicoeur, & Peretz, 2013;Peretz, Brattico, & Tervaniemi, 2005), but also to an impoverished connectivity between the auditory cortex and the inferior frontal cortex (Hyde, Zatorre, & Peretz, 2011). These findings suggest that individuals with amusia have deficits not only at an early stage of pitch discrimination, but also at later stages where a hierarchy of tonal stability and musical expectancies are represented.…”

The basis of musical consonance as revealed by congenital amusia

“…Congenital amusia is a neurogenetic disorder that is characterized by a deficit in melody processing that cannot be explained by hearing loss or intellectual deficiencies (30). Congenital amusia is hereditary (31,32) and is associated with reduced connectivity between the right auditory and inferior frontal cortices (33)(34)(35). The root functional cause of the musical impairments appears to lie in the processing of pitch.…”