Auditory perception and memory deficits in congenital amusia: towards a multisensory rehabilitation – AMUSIA

Music is a universal human trait and ubiquitous in everyday life. However, about 4% of the population is afflicted with a rare perceptual disorder of music perception and production, referred to as congenital amusia. Scientific research about this lifelong disorder has developed only recently, and its behavioral and cerebral underpinnings are still under-investigated. The major deficit in congenital amusia is linked to the processing of the pitch dimension in the auditory signal, thus having destructive consequences for music processing. Pitch discrimination thresholds are generally abnormally high in amusic individuals, and this has been initially interpreted as evidence for a primary deficit in pitch perception. More recent findings have revealed a deficit in short-term memory of pitch information, which seems to be the principal impairment as it can occur without pitch perception deficits.
Our present research project will investigate behavioral and cerebral correlates of pitch perception and memory with two major goals: Firstly, we aim at deciphering the deficits as well as the spared processes linked to pitch perception and memory in congenital amusia by combining behavioral measures and brain imaging studies (with both functional and anatomical methods). Secondly, we intend to pave the way towards a rehabilitation program for amusic individuals, informed by the knowledge already acquired about the perceptual and memory deficits in amusia and by the knowledge about cross-modal interactions and benefits we have gained in previous research.
Our project has three novel, original aspects in comparison to previous research. 1) We will investigate pitch perception and memory in the amusic brain and the normal brain by combining three approaches, namely behavioral, anatomical, and functional imaging methods in the same participants. 2) Our investigations will be using not only, as classically done, explicit investigation methods, but also implicit, indirect investigation methods. The power of implicit processing despite observed explicit failures and deficits has been reported in neuropsychology for a long time in visual perception, language processing and memory, and has been recently extended to music processing, which we will now investigate for congenital amusia. 3) Based on the spared implicit processing capacities, we will combine the investigation of auditory processing with cross-modal interactions. Previously reported audio-visual interactions motivate the development of a research project that exploits cross-modal influences to boost auditory (pitch) processing with concurrent visual information. This allows us to develop and test training methods that should benefit pitch perception and memory.
Beyond these perspectives concerning congenital amusia per se, our research program will more generally deepen our understanding of perceptual and memory processes and their cerebral underpinnings. It will benefit to the understanding of basic brain functioning for the perception and memory of auditory information (music, language), but also its interaction with visual information. Finally, the rehabilitation procedures that we aim to develop could further be transposed to pathologies that also encompass deficits in the processing of the pitch dimension in the auditory signal, such as cochlear hearing loss (in particular for people receiving cochlear implants) or dyslexia.