Impairments in musical abilities reflected in the auditory brainstem: evidence from congenital amusia

Abstract

Congenital amusia is a neurogenetic condition, characterized by a deficit in music perception and production, not explained by hearing loss, brain damage or lack of exposure to music. Despite inferior musical performance, amusics exhibit normal auditory cortical responses, with abnormal neural correlates suggested to lie beyond auditory cortices. Here we show, using auditory brainstem responses to complex sounds in humans, that fine-grained automatic processing of sounds is impoverished in amusia. Compared with matched non-musician controls, spectral amplitude was decreased in amusics for higher harmonic components of the auditory brainstem response. We also found a delayed response to the early transient aspects of the auditory stimulus in amusics. Neural measures of spectral amplitude and response timing correlated with participants' behavioral assessments of music processing. We demonstrate, for the first time, that amusia affects how complex acoustic signals are processed in the auditory brainstem. This neural signature of amusia mirrors what is observed in musicians, such that the aspects of the auditory brainstem responses that are enhanced in musicians are degraded in amusics. By showing that gradients of music abilities are reflected in the auditory brainstem, our findings have implications not only for current models of amusia but also for auditory functioning in general.

Pitch discrimination associated with phonological awareness: Evidence from congenital amusia

“…Pitch discrimination relies on acoustic pitch encoding, which occurs in the ascending auditory pathway and up to the primary auditory cortex37. Recent studies have traced the source of pitch deficits in congenital amusia to early brain responses in the auditory cortex38, or in the brainstem39 (but see ref. 40).…”

Deficits of congenital amusia beyond pitch: Evidence from impaired categorical perception of vowels in Cantonese-speaking congenital amusics

“…Although many previous studies have pointed out that amusia is probably a domain-general deficit of pitch processing [ 21 , 24 , 28 ], it remains unclear whether this deficit is actually pitch specific or not. A few studies have reported possible impairment of amusics in segmental processing (e.g., consonants and vowels) beyond pitch processing, though the picture is far from clear [ 36 , 37 ]. It has been found that amusics exhibited reduced accuracy in the comprehension of news-like Mandarin spoken sentences, even when the F0 contours of the sentences were flattened to neutralize F0 information [ 37 ].…”

“…This finding suggested that amusia affects segmental processing and sentence comprehension apart from pitch processing. Another study has found that the auditory brainstem response to the complex speech sound /da/ was impoverished in the amusic brain, exhibiting reduced spectral amplitude in higher harmonic components of the auditory brainstem response, and a delayed response to the auditory stimulus [ 36 ]. This finding provides further evidence for possibly impaired processing of complex speech sounds, beyond pitch processing, in the amusic brain.…”

Congenital amusics use a secondary pitch mechanism to identify lexical tones

“…Any mechanism for pitch-extraction is likely to reside beyond the superior olive, at or after the lateral lemniscus or the inferior colliculus (Gockel et al, 2011), suggesting that any TFS processing deficit associated with impaired pitch perception in amusia must reside at or central of this stage of the auditory brainstem. Consistent with this, a recent study has failed to find evidence of impaired pitch encoding in the rostral auditory brainstem as indicated by the frequency-following response (Liu et al, 2014, although see also Lehmann et al, 2015).…”