Neuroanatomical correlates of speech and singing production in chronic post-stroke aphasia

Effects of repetitive transcranial magnetic stimulation combined with music therapy in non-fluent aphasia after stroke: A randomised controlled study

BACKGROUND

Although existing studies have shown that both repetitive transcranial magnetic stimulation (rTMS) and music therapy have advantages in the treatment of non-fluent aphasia, the efficacy of the combination of these two methods remains to be investigated.

AIMS

To investigate the clinical efficacy of low-frequency rTMS combined with music therapy on language function and depression in patients with non-fluent aphasia after stroke.

METHODS & PROCEDURES

A single-blind parallel randomised controlled trial was conducted. Sixty patients (mean duration = 93.78 days) with non-fluent aphasia after stroke were randomly divided into a traditional therapy group (n = 20), a music therapy group (n = 20) and a combined therapy group (n = 20, 1 Hz). The language function and depression were evaluated before and 3 weeks after treatment with the Chinese version of the Western Aphasia Battery scale, Boston Diagnostic Aphasia Examination scale and Stroke Aphasic Depression Questionnaire Hospital Version scale.

OUTCOMES & RESULTS

The combined therapy group was significantly better in all outcomes than the traditional therapy group and was significantly better in depression than the music therapy group. The music therapy group was significantly better in repetition and depression than the traditional therapy group. Language improvement was positively correlated with depression improvement. For adverse events, only two patients in the combined therapy group showed slight dizziness during rTMS treatment and their symptoms improved after rest.

CONCLUSIONS & IMPLICATIONS

Our preliminary randomised controlled study indicates that low-frequency rTMS combined with music therapy is feasible and safe in improving language function and depression in non-fluent aphasia patients after stroke.

WHAT THIS PAPER ADDS

What is already known on this subject Repetitive transcranial magnetic stimulation (rTMS) and music therapy respectively have advantages in the treatment of non-fluent aphasia after stroke, but whether the combination of the two methods is more effective is still unknown. What this paper adds to the existing knowledge This is one of the first randomised control trials to investigate whether the clinical efficacy of low-frequency rTMS combined music therapy for non-fluent aphasia is better. The findings show that low-frequency rTMS combined music therapy is superior to traditional therapy in spontaneous speech, auditory comprehension, repetition, naming, aphasia quotient, functional language level and depression, and superior to music therapy in depression, while music therapy is superior to traditional therapy in repetition and depression. What are the potential or actual clinical implications of this work? Low-frequency rTMS combined music therapy may be a better method for treatment of non-fluent aphasia.

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

Background

Understanding 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.

Methods

The 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).

Results

In 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.

Conclusion

The 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.

Hodological organization of spoken language production and singing in the human brain

Theories expounding the neural relationship between speech and singing range from sharing neural circuitry, to relying on opposite hemispheres. Yet, hodological studies exploring their shared and distinct neural networks remain scarce. In this study, we combine a white matter connectometry approach together with comprehensive and naturalistic appraisal of verbal expression during spoken language production and singing in a sample of individuals with post-stroke aphasia. Our results reveal that both spoken language production and singing are mainly supported by the left hemisphere language network and projection pathways. However, while spoken language production mostly engaged dorsal and ventral streams of speech processing, singing was associated primarily with the left ventral stream. These findings provide evidence that speech and singing share core neuronal circuitry within the left hemisphere, while distinct ventral stream contributions explain frequently observed dissociations in aphasia. Moreover, the results suggest prerequisite biomarkers for successful singing-based therapeutic interventions.

Segregated circuits for phonemic and semantic fluency: A novel patient-tailored disconnection study

Phonemic and semantic fluency are neuropsychological tests widely used to assess patients' language and executive abilities and are highly sensitive tests in detecting language deficits in glioma patients. However, the networks that are involved in these tasks could be distinct and suggesting either a frontal (phonemic) or temporal (semantic) involvement. 42 right-handed patients (26 male, mean age = 52.5 years, SD=±13.3) were included in this retrospective study. Patients underwent awake (54.8%) or asleep (45.2%) surgery for low-grade (16.7%) or high-grade-glioma (83.3%) in the frontal (64.3%) or temporal lobe (35.7%) of the left (50%) or right (50%) hemisphere. Pre-operative tractography was reconstructed for each patient, with segmentation of the inferior fronto-occipital fasciculus (IFOF), arcuate fasciculus (AF), uncinate fasciculus (UF), inferior longitudinal fasciculus (ILF), third branch of the superior longitudinal fasciculus (SLF-III), frontal aslant tract (FAT), and cortico-spinal tract (CST). Post-operative percentage of damage and disconnection of each tract, based on the patients' surgical cavities, were correlated with verbal fluencies scores at one week and one month after surgery. Analyses of differences between fluency scores at these timepoints (before surgery, one week and one month after surgery) were performed; lesion-symptom mapping was used to identify the correlation between cortical areas and post-operative scores. Immediately after surgery, a transient impairment of verbal fluency was observed, that improved within a month. Left hemisphere lesions were related to a worse verbal fluency performance, being a damage to the left superior frontal or temporal gyri associated with phonemic or semantic fluency deficit, respectively. At a subcortical level, disconnection analyses revealed that fluency scores were associated to the involvement of the left FAT and the left frontal part of the IFOF for phonemic fluency, and the association was still present one month after surgery. For semantic fluency, the correlation between post-surgery performance emerged for the left AF, UF, ILF and the temporal part of the IFOF, but disappeared at the follow-up. This approach based on the patients' pre-operative tractography, allowed to trace for the first time a dissociation between white matter pathways integrity and verbal fluency after surgery for glioma resection. Our results confirm the involvement of a frontal anterior pathway for phonemic fluency and a ventral temporal pathway for semantic fluency. Finally, our longitudinal results suggest that the frontal executive pathway requires a longer interval to recover compared to the semantic one.

Potential Benefits of Music Therapy on Stroke Rehabilitation

Stroke is associated with a high rate of disability and mortality, and survivors are usually accompanied with dysphagia, aphasia, motor dysfunction, cognitive impairment, depression, and other complications. In the past decades, many studies have been conducted to reveal the pathogenesis and pathological mechanisms of stroke. Furthermore, treatment methods have been developed that contribute to the elevated survival rate of stroke patients. Early rehabilitation poststroke is starting to be recognized as important and has been receiving increasing attention in order to further improve the quality of life of the patients. As an emerging method of poststroke rehabilitation, music therapy can help attenuate dysphagia and aphasia, improve cognition and motor function, alleviate negative moods, and accelerate neurological recovery in stroke patients. This review helps summarize the recent progress that has been made using music therapy in stroke rehabilitation and is aimed at providing clinical evidence for the treatment of stroke patients.