Neural basis of acquired amusia and its recovery

In acquired amusia, the healthy music processing system in the brain is disrupted due to focal brain damage. This creates an exceptional opportunity to investigate the critical neural architectures of music processing. Yet, the neural basis of acquired amusia has remained largely unexplored. In this multimodal magnetic resonance imaging (MRI) study of stroke patients with a 6-month follow-up, we systematically explored the neural basis of music processing by determining the lesions patterns, structural grey and white matter changes, and brain activation and functional network connectivity changes associated with acquired amusia and its recovery. We found that damage to the right temporal areas, insula, and putamen forms the crucial neural substrate for acquired amusia after stroke. Longitudinally, persistent amusia was associated with further atrophy in the right superior temporal regions, located more anteriorly for rhythm-amusia and more posteriorly for pitchamusia. In addition, persistent amusia was associated with structural damage and later degeneration in multiple right frontotemporal and frontal pathways as well as interhemispheric connections. Interestingly, rhythm-amusia was associated with additional deficits in left frontal connectivity. During listening to instrumental music, acquired amusics exhibited dysfunction of multiple frontal and temporal brain regions included in the large-scale music network. Interestingly, amusics showed less activation deficits during listening to vocal music, as compared to instrumental music, suggesting less defective processing of singing. Recovery from acquired amusia was related to increased activation in the right frontal and parietal areas as well as increased functional connectivity in the right and left frontoparietal networks. Overall, the results provide a comprehensive neuroanatomical and functional picture of acquired amusia and highlight the neural structures crucial for normal music perception.Aivoinfarktin ja -verenvuodon jälkeinen musiikin käsittelyn häiriö ja siitä kuntoutuminen Hankinnaisessa amusiassa aivojen musiikinkäsittelyjärjestelmän normaali toiminta häiriintyy aivojen paikallisen vaurioitumisen takia. Tämä luo poikkeuksellisen mahdollisuuden tutkia musiikin käsittelylle tärkeitä aivorakenteita. Hankinnaisen amusian aivoperusta on kuitenkin suurelta osin vielä täysin tuntematonta. Tässä aivoverenkiertohäiriön (AVH) sairastaneiden potilaiden 6 kuukauden seurantatutkimuksessa selvitimme magneettikuvantamisen avulla musiikin käsittelyn aivoperustaa tutkimalla, minkä aivoalueiden vauriot, mitkä harmaan ja valkean aineen rakenteelliset muutokset ja millaiset aivojen toiminnalliset muutokset liittyvät hankinnaiseen amusiaan ja siitä kuntoutumiseen. Tuloksemme osoittivat, että AVH:n jälkeinen amusia syntyy oikean ohimolohkon yläosan, aivosaaren ja tyvitumakealueen vauriosta. Pysyvään amusiaan liittyi lisäksi harmaan aineen atrofiaa oikeassa ohimolohkossa. Rytmin havaitsemiseen liittyvässä amusiassa atrofia painottui ohimolohkon etuosaan ja äänenkorkeuden havaitsemiseen liittyvässä amusiassa ohimolohkon takaosaan. Lisäksi, pysyvään amusiaan liittyi laaja oikean aivopuoliskon ja aivopuoliskon välisten radastojen vaurio ja atrofia. Amusia aiheutti myös laajamittaisia aivojen toimintahäiriöitä musiikin kuuntelun aikana. Mielenkiintoista on, että toimintahäiriöt olivat suurempia kuunneltaessa instrumentaalimusiikkia kuin laulettua musiikkia. Amusiasta kuntoutuminen oli yhteydessä toiminnallisten yhteyksien vahvistumiseen oikean sekä vasemman aivopuoliskon otsa- ja päälakilohkojen välillä. Tulokset antavat kattavan kuvan amusiaan johtavista aivovaurioista sekä siihen liittyvistä rakenteellisista ja toiminnallisista muutoksista. Lisäksi tulokset valottavat musiikin käsittelylle keskeisen tärkeitä aivorakenteita

Golden oldies and silver brains : Deficits, preservation, learning, and rehabilitation effects of music in ageing-related neurological disorders

During the last decades, there have been major advances in mapping the brain regions that underlie our ability to perceive, experience, and produce music and how musical training can shape the structure and function of the brain. This progress has fueled and renewed clinical interest towards uncovering the neural basis for the impaired or preserved processing of music in different neurological disorders and how music-based interventions can be used in their rehabilitation and care. This article reviews our contribution to and the state-of-the-art of this field. We will provide a short overview outlining the key brain networks that participate in the processing of music and singing in the healthy brain and then present recent findings on the following key music-related research topics in neurological disorders: (i) the neural architecture underlying deficient processing of music (amusia), (ii) the preservation of singing in aphasia and music-evoked emotions and memories in Alzheimer's disease, (iii) the mnemonic impact of songs as a verbal learning tool, and (iv) the cognitive, emotional, and neural efficacy of music-based interventions and activities in the rehabilitation and care of major ageing-related neurological illnesses (stroke, Alzheimer's disease, and Parkinson's disease). (C) 2018 Elsevier Ltd. All rights reserved.Peer reviewe

Clinical and Neural Predictors of Treatment Response to Music Listening Intervention after Stroke

Patients with post-stroke impairments present often significant variation in response to therapeutic interventions. Recent studies have shown that daily music listening can aid post-stroke recovery of language and memory, but reliable predictors of treatment response are unknown. Utilizing data from the music intervention arms of a single-blind randomized controlled trial (RCT) on stroke patients (N = 31), we built regression models to predict the treatment response of a two-month music listening intervention on language skills and verbal memory with baseline demographic, clinical and musical data as well as fMRI data from a music listening task. Clinically, greater improvement in verbal memory and language skills after the music listening intervention were predicted by the severity of the initial deficit and educational level. Neurally, greater baseline fMRI activation during vocal music listening in the left parietal cortical and medial frontal areas predicted greater treatment-induced improvement in language skills and greater baseline engagement of the auditory network during instrumental music listening predicted improvement in both verbal memory and language skills. Our results suggest that clinical, demographic, and neuroimaging data predicts music listening treatment response. This data could be used clinically to target music-based treatments.Peer reviewe

Post-stroke enriched auditory environment induces structural connectome plasticity : secondary analysis from a randomized controlled trial

Post-stroke neuroplasticity and cognitive recovery can be enhanced by multimodal stimulation via environmental enrichment. In this vein, recent studies have shown that enriched sound environment (i.e., listening to music) during the subacute post-stroke stage improves cognitive outcomes compared to standard care. The beneficial effects of post-stroke music listening are further pronounced when listening to music containing singing, which enhances language recovery coupled with structural and functional connectivity changes within the language network. However, outside the language network, virtually nothing is known about the effects of enriched sound environment on the structural connectome of the recovering post-stroke brain. Here, we report secondary outcomes from a single-blind randomized controlled trial (NCT01749709) in patients with ischaemic or haemorrhagic stroke (N = 38) who were randomly assigned to listen to vocal music, instrumental music, or audiobooks during the first 3 post-stroke months. Utilizing the longitudinal diffusion-weighted MRI data of the trial, the present study aimed to determine whether the music listening interventions induce changes on structural white matter connectome compared to the control audiobook intervention. Both vocal and instrumental music groups increased quantitative anisotropy longitudinally in multiple left dorsal and ventral tracts as well as in the corpus callosum, and also in the right hemisphere compared to the audiobook group. Audiobook group did not show increased structural connectivity changes compared to both vocal and instrumental music groups. This study shows that listening to music, either vocal or instrumental promotes wide-spread structural connectivity changes in the post-stroke brain, providing a fertile ground for functional restoration.Peer reviewe

Differential effects of ageing on the neural processing of speech and singing production

BackgroundUnderstanding healthy brain ageing has become vital as populations are ageing rapidly and age-related brain diseases are becoming more common. In normal brain ageing, speech processing undergoes functional reorganisation involving reductions of hemispheric asymmetry and overactivation in the prefrontal regions. However, little is known about how these changes generalise to other vocal production, such as singing, and how they are affected by associated cognitive demands.MethodsThe present cross-sectional fMRI study systematically maps the neural correlates of vocal production across adulthood (N=100, age 21–88 years) using a balanced 2x3 design where tasks varied in modality (speech: proverbs / singing: song phrases) and cognitive demand (repetition / completion from memory / improvisation).ResultsIn speech production, ageing was associated with decreased left pre- and postcentral activation across tasks and increased bilateral angular and right inferior temporal and fusiform activation in the improvisation task. In singing production, ageing was associated with increased activation in medial and bilateral prefrontal and parietal regions in the completion task, whereas other tasks showed no ageing effects. Direct comparisons between the modalities showed larger age-related activation changes in speech than singing across tasks, including a larger left-to-right shift in lateral prefrontal regions in the improvisation task.ConclusionThe present results suggest that the brains’ singing network undergoes differential functional reorganisation in normal ageing compared to the speech network, particularly during a task with high executive demand. These findings are relevant for understanding the effects of ageing on vocal production as well as how singing can support communication in healthy ageing and neurological rehabilitation

Structural white matter connectometry of reading and dyslexia

Current views on the neural network subserving reading and its deficits in dyslexia rely largely on evidence derived from functional neuroimaging studies. However, understanding the structural organization of reading and its aberrations in dyslexia requires a hodological approach, studies of which have not provided consistent findings. Here, we adopted a whole brain hodological approach and investigated relationships between structural white matter connectivity and reading skills and phonological processing in a cross-sectional study of 44 adults using individual local connectome matrix from diffusion MRI data. Moreover, we performed quantitative anisotropy aided differential tractography to uncover structural white matter anomalies in dyslexia (23 dyslexics and 21 matched controls) and their correlation to reading-related skills. The connectometry analyses indicated that reading skills and phonological processing were both associated with corpus callosum (tapetum), forceps major and minor, as well as cerebellum bilaterally. Furthermore, the left dorsal and right thalamic pathways were associated with phonological processing. Differential tractography analyses revealed structural white matter anomalies in dyslexics in the left ventral route and bilaterally in the dorsal route compared to the controls. Connectivity deficits were also observed in the corpus callosum, forceps major, vertical occipital fasciculus and corticostriatal and thalamic pathways. Altered structural connectivity in the observed differential tractography results correlated with poor reading skills and phonological processing. Using a hodological approach, the current study provides novel evidence for the extent of the reading-related connectome and its aberrations in dyslexia. The results conform current functional neuroanatomical models of reading and developmental dyslexia but provide novel network-level and tract-level evidence on structural connectivity anomalies in dyslexia, including the vertical occipital fasciculus.Peer reviewe

Beyond volume : A surface-based approach to bilingualism-induced grey matter changes

Bilingualism is a sustained experience associated with structural changes in cortical grey matter (GM) morphology. Apart from a few studies, a dominant method used to assess bilingualism-induced GM changes has been the voxel-based morphometry (VBM) analysis. While VBM is sensitive to GM volume/density differences in general, it cannot be used to identify whether the observed difference is due to relative changes in, e.g., cortical thickness, area or folding, as it uses a single combined measure of them all. Here, we used surface-based analysis (SBA) approach to investigate whether early acquisition of a second language (L2) affects the cortical GM morphology relative to late L2 acquisition. More specifically, our aim was to test a hypothesis that early acquisition of two languages induces GM changes that are predominantly surface area-driven, while late acquisition is supposedly characterised with primarily thickness-driven changes. To this end, several surface-based measures were concurrently compared between the groups. In line with the hypothesis, the results revealed that early bilingual experience is associated with significantly extended cortical surface area over the left pars opercularis and the right superior temporal gyrus. Contrary to our expectations, however, we found no evidence supporting the postulated association between late L2 acquisition and increased cortical thickness. Nevertheless, our study highlights the importance of including cortical surface measures when investigating bilingualism related GM modulations.Peer reviewe

Resting-state language network neuroplasticity in post-stroke music listening: A randomized controlled trial

Recent evidence suggests that post-stroke vocal music listening can aid language recovery, but the network-level functional neuroplasticity mechanisms of this effect are unknown. Here, we sought to determine if improved language recovery observed after post-stroke listening to vocal music is driven by changes in longitudinal resting-state functional connectivity within the language network. Using data from a single-blind randomized controlled trial on stroke patients (N = 38), we compared the effects of daily listening to self-selected vocal music, instrumental music and audio books on changes of the resting-state functional connectivity within the language network and their correlation to improved language skills and verbal memory during the first 3 months post-stroke. From acute to 3-month stage, the vocal music and instrumental music groups increased functional connectivity between a cluster comprising the left inferior parietal areas and the language network more than the audio book group. However, the functional connectivity increase correlated with improved verbal memory only in the vocal music group cluster. This study shows that listening to vocal music post-stroke promotes recovery of verbal memory by inducing changes in longitudinal functional connectivity in the language network. Our results conform to the variable neurodisplacement theory underpinning aphasia recovery.Peer reviewe

Musiikillinen häiriö aivovaurion jälkeen - yleinen mutta harvoin tunnistettu oire?

Musiikin havaitsemisen ja tuottamisen häiriö (amusia) ei ole tavanomaisessa kliinisessä työssä arvioitu oire, vaikka sitä esiintyy jopa puolella akuutin aivoverenkiertohäiriön sairastaneista potilaista. Amusiaa esiintyy yleisimmin oikean ohimo- ja otsalohkon sekä aivosaaren (insula) vaurioiden jälkeen, mutta sitä tavataan myös vasemman aivopuoliskon vaurion yhteydessä, joskin usein lievempänä ja ohimenevänä. Amusiaan liittyvät oikean aivopuoliskon valkean aineen ratojen, etenkin ventraalisen radaston, vaurio sekä ohimo- ja otsalohkon harmaan aineen atrofia ja toiminnalliset muutokset. Amusiassa myös puheen prosodisten piirteiden käsittely häiriintyy, mikä heikentää potilaiden arkipäivän kommunikointia ja sosiaalista kanssakäymistä. Laulaminen vaikuttaa lupaavalta amusian kuntoutusmuodolta, mutta aivovauriopotilaita käsitteleviä interventiotutkimuksia ei ole vielä julkaistu

Musiikillinen häiriö aivovaurion jälkeen - yleinen mutta harvoin tunnistettu oire?

Vertaisarvioitu.Musiikin havaitsemisen ja tuottamisen häiriö (amusia) ei ole tavanomaisessa kliinisessä työssä arvioitu oire, vaikka sitä esiintyy jopa puolella akuutin aivoverenkiertohäiriön sairastaneista potilaista. Amusiaa esiintyy yleisimmin oikean ohimo- ja otsalohkon sekä aivosaaren (insula) vaurioiden jälkeen, mutta sitä tavataan myös vasemman aivopuoliskon vaurion yhteydessä, joskin usein lievempänä ja ohimenevänä. Amusiaan liittyvät oikean aivopuoliskon valkean aineen ratojen, etenkin ventraalisen radaston, vaurio sekä ohimo- ja otsalohkon harmaan aineen atrofia ja toiminnalliset muutokset. Amusiassa myös puheen prosodisten piirteiden käsittely häiriintyy, mikä heikentää potilaiden arkipäivän kommunikointia ja sosiaalista kanssakäymistä. Laulaminen vaikuttaa lupaavalta amusian kuntoutusmuodolta, mutta aivovauriopotilaita käsitteleviä interventiotutkimuksia ei ole vielä julkaistu.Peer reviewe