The functional neuroanatomy of musical memory in Alzheimer's disease

Abstract

Background Memory for music has attracted much recent interest in Alzheimer's disease but the underlying brain mechanisms have not been defined in patients directly. Here we addressed this issue in an Alzheimer's disease cohort using activation fMRI of two core musical memory systems. Methods We studied 34 patients with younger onset Alzheimer's disease led either by episodic memory decline (typical Alzheimer's disease) or by visuospatial impairment (posterior cortical atrophy) in relation to 19 age-matched healthy individuals. We designed a novel fMRI paradigm based on passive listening to melodies that were either previously familiar or unfamiliar (musical semantic memory) and either presented singly or repeated (incidental musical episodic memory). Results Both syndromic groups showed significant functional neuroanatomical alterations relative to the healthy control group. For musical semantic memory, disease-associated activation group differences were localised to right inferior frontal cortex (reduced activation in the group with memory-led Alzheimer's disease); while for incidental musical episodic memory, disease-associated activation group differences were localised to precuneus and posterior cingulate cortex (abnormally enhanced activation in the syndromic groups). In post-scan behavioural testing, both patient groups had a deficit of musical episodic memory relative to healthy controls whereas musical semantic memory was unimpaired. Conclusions Our findings define functional neuroanatomical substrates for the differential involvement of musical semantic and incidental episodic memory in major phenotypes of Alzheimer's disease. The complex dynamic profile of brain activation group differences observed suggests that musical memory may be an informative probe of neural network function in Alzheimer's disease. These findings may guide the development of future musical interventions in dementia.

Impairments of auditory scene analysis in posterior cortical atrophy

“…Our findings corroborate earlier work suggesting that there may be a prominent auditory contribution to the PCA phenotype (Crutch et al, 2013;Golden et al, 2015;Slattery et al, 2019). The ASA-segregation and ASA-grouping tasks used here were developed to probe fundamental processes in the disambiguation and understanding of auditory scenes.…”

“…In the realm of sound, both PCA and typical amnestic Alzheimer's disease adversely affect the processing of auditory spatial information, leading to impaired detection of sound source motion and localization of stationary sounds in space (Golden et al, 2015). Such deficits are likely to contribute to impaired navigation of complex, everyday environments in both PCA and typical amnestic Alzheimer's disease, and may form part of a wider spectrum of central auditory dysfunction in these syndromes (Crutch et al, 2013;Slattery et al, 2019). Taken together, this evidence suggests that central auditory impairment may be more significant in PCA than generally recognized.…”

Music and emotion in Alzheimer’s disease

“…Besides, several studies have showed that recognition memory was better for the novel sung than spoken lyrics in AD patients [22, 24, 25]. Familiarity of music also is another aspect taken into account to explain the variability of music memory in AD patients [2, 18, 33, 41, 42]. In this sense, the recent study of Slaterry et al [42] found out that in AD patients, unfamiliar melodies depended more on episodic memory, involving disease-associated activation group differences in precuneus and posterior cingulate cortex, and familiar melodies depended more on semantic memory, involving activation differences in right inferior frontal cortex.…”

“…Familiarity of music also is another aspect taken into account to explain the variability of music memory in AD patients [2, 18, 33, 41, 42]. In this sense, the recent study of Slaterry et al [42] found out that in AD patients, unfamiliar melodies depended more on episodic memory, involving disease-associated activation group differences in precuneus and posterior cingulate cortex, and familiar melodies depended more on semantic memory, involving activation differences in right inferior frontal cortex. In addition, Baird and Samson [18] suggested that perhaps the implicit and procedural memories for musical stimuli remain preserved, but not musical episodic memory.…”

Links Between the Neurobiology of Oxytocin and Human Musicality

“…From an evolutionary perspective, it may clarify the extent to which evolving musical capabilities in modern humans took advantage of the ancient oxytocinergic network to facilitate prosocial interactions, promote trust and reciprocal affiliative behaviors, and help reduce levels of anxiety and individual insecurity throughout life. It will also contribute to a better understanding of the mechanisms that underlie the mental and general health benefits of music, its remarkable emotional and mnemonic power, it’s capacity to alter brain architecture, and its ability to revitalize episodic memories (Zhang et al, 2017 ; Särkämö and Sihvonen, 2018 ), especially vulnerable in early stages of Alzheimer’s disease (Groussard et al, 2019 ; Slattery et al, 2019 ).…”