A domain-general perspective on the role of the basal ganglia in language and music: Benefits of music therapy for the treatment of aphasia

A modified neural circuit framework for semantic memory retrieval with implications for circuit modulation to treat verbal retrieval deficits

Word finding difficulty is a frequent complaint in older age and disease states, but treatment options are lacking for such verbal retrieval deficits. Better understanding of the neurophysiological and neuroanatomical basis of verbal retrieval function may inform effective interventions. In this article, we review the current evidence of a neural retrieval circuit central to verbal production, including words and semantic memory, that involves the pre-supplementary motor area (pre-SMA), striatum (particularly caudate nucleus), and thalamus. We aim to offer a modified neural circuit framework expanded upon a memory retrieval model proposed in 2013 by Hart et al., as evidence from electrophysiological, functional brain imaging, and noninvasive electrical brain stimulation studies have provided additional pieces of information that converge on a shared neural circuit for retrieval of memory and words. We propose that both the left inferior frontal gyrus and fronto-polar regions should be included in the expanded circuit. All these regions have their respective functional roles during verbal retrieval, such as selection and inhibition during search, initiation and termination of search, maintenance of co-activation across cortical regions, as well as final activation of the retrieved information. We will also highlight the structural connectivity from and to the pre-SMA (e.g., frontal aslant tract and fronto-striatal tract) that facilitates communication between the regions within this circuit. Finally, we will discuss how this circuit and its correlated activity may be affected by disease states and how this circuit may serve as a novel target engagement for neuromodulatory treatment of verbal retrieval deficits.

Treatment of Subcortical Aphasia Due to Putaminal Hemorrhage With the Japanese Version of Melodic Intonation Therapy (MIT-J)

Melodic intonation therapy (MIT) is one of the rehabilitation methods for patients with non-fluent or dysfluent aphasia, mainly caused by stroke or brain injury. Although MIT is conducted in various languages, reports on the Japanese version of MIT (MIT-J) are limited. In this report, we describe a case about the efficacy of MIT-J in the subacute phase after stroke on subcortical aphasia. Our case was a 60-year-old right-handed woman who suffered from left putaminal hemorrhage. She was treated with acute therapy, including medications and rehabilitation, but non-fluent aphasia was preserved. Regardless of general speech therapies, her aphasia was not improved. In the subacute phase, we started MIT-J (protocol: 20 minutes per day, five days per week for two weeks). The effect of MIT-J was remarkable and in particular, speech intelligibility was improved. It is required to accumulate more cases to reveal the effect of MIT-J.

Music Therapy in Global Aphasia: A Case Report

Patients affected by global aphasia are no longer able to understand, produce, name objects, write and read. It occurs as a result of functional damage of ischemic or hemorrhagic origin affecting the entire peri-silvan region and frontal operculum. Rehabilitation training aims to promote an early intervention in the acute phase. We described a case of a 57-year-old female patient with left intraparenchymal fronto-temporo-parietal cerebral hemorrhage and right hemiplegia. After admission to clinical rehabilitative center, the patient was not able to perform simple orders and she presented a severe impairment of auditory and written comprehension. Eloquence was characterized by stereotypical emission of monosyllabic sounds and showed compromised praxis-constructive abilities. Rehabilitation included a program of Neurologic Music Therapy (NMT), specifically Symbolic Communication Training Through Music (SYCOM) and Musical Speech Stimulation (MUSTIM). Rehabilitative treatment was measured by improved cognitive and language performance of the patient from T0 to T1. Music rehabilitative interventions and continuous speech therapy improve visual attention and communicative intentionality. In order to confirm the effectiveness of data presented, further extensive studies of the sample would be necessary, to assess the real role of music therapy in post-stroke global aphasia.

The contribution of white matter pathology, hypoperfusion, lesion load, and stroke recurrence to language deficits following acute subcortical left hemisphere stroke

Aphasia, the loss of language ability following damage to the brain, is among the most disabling and common consequences of stroke. Subcortical stroke, occurring in the basal ganglia, thalamus, and/or deep white matter can result in aphasia, often characterized by word fluency, motor speech output, or sentence generation impairments. The link between greater lesion volume and acute aphasia is well documented, but the independent contributions of lesion location, cortical hypoperfusion, prior stroke, and white matter degeneration (leukoaraiosis) remain unclear, particularly in subcortical aphasia. Thus, we aimed to disentangle the contributions of each factor on language impairments in left hemisphere acute subcortical stroke survivors. Eighty patients with acute ischemic left hemisphere subcortical stroke (less than 10 days post-onset) participated. We manually traced acute lesions on diffusion-weighted scans and prior lesions on T2-weighted scans. Leukoaraiosis was rated on T2-weighted scans using the Fazekas et al. (1987) scale. Fluid-attenuated inversion recovery (FLAIR) scans were evaluated for hyperintense vessels in each vascular territory, providing an indirect measure of hypoperfusion in lieu of perfusion-weighted imaging. We found that language performance was negatively correlated with acute/total lesion volumes and greater damage to substructures of the deep white matter and basal ganglia. We conducted a LASSO regression that included all variables for which we found significant univariate relationships to language performance, plus nuisance regressors. Only total lesion volume was a significant predictor of global language impairment severity. Further examination of three participants with severe language impairments suggests that their deficits result from impairment in domain-general, rather than linguistic, processes. Given the variability in language deficits and imaging markers associated with such deficits, it seems likely that subcortical aphasia is a heterogeneous clinical syndrome with distinct causes across individuals.

The longitudinal neural dynamics changes of whole brain connectome during natural recovery from poststroke aphasia

Poststroke aphasia is one of the most dramatic functional deficits that results from direct damage of focal brain regions and dysfunction of large-scale brain networks. The reconstruction of language function depends on the hierarchical whole-brain dynamic reorganization. However, investigations into the longitudinal neural changes of large-scale brain networks for poststroke aphasia remain scarce. Here we characterize large-scale brain dynamics in left-frontal-stroke aphasia through energy landscape analysis. Using fMRI during an auditory comprehension task, we find that aphasia patients suffer serious whole-brain dynamics perturbation in the acute and subacute stages after stroke, in which the brains were restricted into two major activity patterns. Following spontaneous recovery process, the brain flexibility improved in the chronic stage. Critically, we demonstrated that the abnormal neural dynamics are correlated with the aberrant brain network coordination. Taken together, the energy landscape analysis exhibited that the acute poststroke aphasia has a constrained, low dimensional brain dynamics, which were replaced by less constrained and high dimensional dynamics at chronic aphasia. Our study provides a new perspective to profoundly understand the pathological mechanisms of poststroke aphasia.

Long Short-Term Memory-Based Music Analysis System for Music Therapy

Music can express people's thoughts and emotions. Music therapy is to stimulate and hypnotize the human brain by using various forms of music activities, such as listening, singing, playing and rhythm. With the empowerment of artificial intelligence, music therapy technology has made innovative development in the whole process of "diagnosis, treatment and evaluation." It is necessary to make use of the advantages of artificial intelligence technology to innovate music therapy methods, ensure the accuracy of treatment schemes, and provide more paths for the development of the medical field. This paper proposes an long short-term memory (LSTM)-based generation and classification algorithm for multi-voice music data. A Multi-Voice Music Generation system called MVMG based on the algorithm is developed. MVMG contains two main steps. At first, the music data are modeled to the MDPI and text sequence data by using an autoencoder model, including music features extraction and music clip representation. And then an LSTM-based music generation and classification model is developed for generating and analyzing music in specific treatment scenario. MVMG is evaluated based on the datasets collected by us: the single-melody MIDI files and the Chinese classical music dataset. The experiment shows that the highest accuracy of the autoencoder-based feature extractor can achieve 95.3%. And the average F1-score of LSTM is 95.68%, which is much higher than the DNN-based classification model.

fNIRS-Based Dynamic Functional Connectivity Reveals the Innate Musical Sensing Brain Networks in Preterm Infants

Humans have the ability to appreciate and create music. However, why and how humans have this distinctive ability to perceive music remains unclear. Additionally, the investigation of the innate perceiving skill in humans is compounded by the fact that we have been actively and passively exposed to auditory stimuli or have systematically learnt music after birth. Therefore, to explore the innate musical perceiving ability, infants with preterm birth may be the most suitable population. In this study, the auditory brain networks were explored using dynamic functional connectivity-based reliable component analysis (RCA) in preterm infants during music listening. The brain activation was captured by portable functional near-infrared spectroscopy (fNIRS) to simulate a natural environment for preterm infants. The components with the maximum inter-subject correlation were extracted. The generated spatial filters identified the shared spatial structural features of functional brain connectivity across subjects during listening to the common music, exhibiting a functional synchronization between the right temporal region and the frontal and motor cortex, and synchronization between the bilateral temporal regions. The specific pattern is responsible for the functions involving music comprehension, emotion generation, language processing, memory, and sensory. The fluctuation of the extracted components and the phase variation demonstrates the interactions between the extracted brain networks to encode musical information. These results are critically important for our understanding of the underlying mechanisms of the innate perceiving skills at early ages of human during naturalistic music listening.

The effect of music therapy on language recovery in patients with aphasia after stroke: a systematic review and meta-analysis

OBJECTIVE

The aim of this meta-analysis was to evaluate the evidence on the effectiveness of music therapy in the recovery of language function in post-stroke aphasia, compared with conventional therapy or no therapy.

METHODS

We searched studies that explored the effect of music therapy on language function in post-stroke aphasia and published in PubMed, Embase, the Cochrane Library, Web of Science, CINAHL, ProQuest Digital Dissertations, and ClinicalTrials.gov from inception to March 2021. Six reviewers independently screened out eligible studies, extracted data, and evaluated the methodological quality. Results were pooled using mean difference (MD) with 95% confidence interval (CI). Heterogeneity was assessed by the chi-square test and I² statistic.

RESULTS

Six studies were included in this meta-analysis involving 115 patients. The methodological quality of these studies ranged from poor to excellent. There was significant mean difference in functional communication for post-stroke aphasia by 1.45 (95% CI: 0.24, 2.65; P = 0.02, from poor to excellent evidence), in repetition by 6.49 (95% CI: 0.97, 12.00; P = 0.02, from acceptable to excellent evidence), and in naming by 11.44 (95% CI: 1.63, 21.26; P = 0.02, from acceptable to excellent evidence). But there was no significant difference in comprehension for post-stroke aphasia by 7.21 (95% CI: - 10.88, 25.29; P = 0.43, from acceptable to excellent evidence).

CONCLUSIONS

Music therapy can improve functional communication, repetition, and naming in patients with post-stroke aphasia, but did not significantly improve comprehension.

TRIAL REGISTRATION

CRD42021251526.

Subcortical Aphasia

PURPOSE OF REVIEW

Subcortical structures have long been thought to play a role in language processing. Increasingly spirited debates on language studies, arising from as early as the nineteenth century, grew remarkably sophisticated as the years pass. In the context of non-thalamic aphasia, a few theoretical frameworks have been laid out. The disconnection hypothesis postulates that basal ganglia insults result in aphasia due to a rupture of connectivity between Broca and Wernicke's areas. A second viewpoint conjectures that the basal ganglia would more directly partake in language processing, and a third stream proclaims that aphasia would stem from cortical deafferentation. On the other hand, thalamic aphasia is more predominantly deemed as a resultant of diaschisis. This article reviews the above topics with recent findings on deep brain stimulation, neurophysiology, and aphasiology.

RECENT FINDINGS

The more recent approach conceptualizes non-thalamic aphasias as the offspring of unpredictable cortical hypoperfusion. Regarding the thalamus, there is mounting evidence now pointing to leading contributions of the pulvinar/lateral posterior nucleus and the anterior/ventral anterior thalamus to language disturbances. While the former appears to relate to lexical-semantic indiscrimination, the latter seems to bring about a severe breakdown in word selection and/or spontaneous top-down lexical-semantic operations. The characterization of subcortical aphasias and the role of the basal ganglia and thalamus in language processing continues to pose a challenge. Neuroimaging studies have pointed a path forward, and we believe that more recent methods such as tractography and connectivity studies will significantly expand our knowledge in this particular area of aphasiology.

In Time with the Beat: Entrainment in Patients with Phonological Impairment, Apraxia of Speech, and Parkinson's Disease

In the present study, we investigated if individuals with neurogenic speech sound impairments of three types, Parkinson’s dysarthria, apraxia of speech, and aphasic phonological impairment, accommodate their speech to the natural speech rhythm of an auditory model, and if so, whether the effect is more significant after hearing metrically regular sentences as compared to those with an irregular pattern. This question builds on theories of rhythmic entrainment, assuming that sensorimotor predictions of upcoming events allow humans to synchronize their actions with an external rhythm. To investigate entrainment effects, we conducted a sentence completion task relating participants’ response latencies to the spoken rhythm of the prime heard immediately before. A further research question was if the perceived rhythm interacts with the rhythm of the participants’ own productions, i.e., the trochaic or iambic stress pattern of disyllabic target words. For a control group of healthy speakers, our study revealed evidence for entrainment when trochaic target words were preceded by regularly stressed prime sentences. Persons with Parkinson’s dysarthria showed a pattern similar to that of the healthy individuals. For the patient groups with apraxia of speech and with phonological impairment, considerably longer response latencies with differing patterns were observed. Trochaic target words were initiated with significantly shorter latencies, whereas the metrical regularity of prime sentences had no consistent impact on response latencies and did not interact with the stress pattern of the target words to be produced. The absence of an entrainment in these patients may be explained by the more severe difficulties in initiating speech at all. We discuss the results in terms of clinical implications for diagnostics and therapy in neurogenic speech disorders.

Why language survives as the dominant communication tool: A neurocognitive perspective

By focusing on the contributions of subcortical structures, our commentary suggests that the functions of the hippocampus underlying "displacement," a feature enabling humans to communicate things and situations that are remote in space and time, make language more effective at social bonding. Based on the functions of the basal ganglia and hippocampus, evolutionary trajectory of the subcomponents of music and language in different species will also be discussed.

Hierarchical control as a shared neurocognitive mechanism for language and music

Although comparative research has made substantial progress in clarifying the relationship between language and music as neurocognitive systems from both a theoretical and empirical perspective, there is still no consensus about which mechanisms, if any, are shared and how they bring about different neurocognitive systems. In this paper, we tackle these two questions by focusing on hierarchical control as a neurocognitive mechanism underlying syntax in language and music. We put forward the Coordinated Hierarchical Control (CHC) hypothesis: linguistic and musical syntax rely on hierarchical control, but engage this shared mechanism differently depending on the current control demand. While linguistic syntax preferably engages the abstract rule-based control circuit, musical syntax rather employs the coordination of the abstract rule-based and the more concrete motor-based control circuits. We provide evidence for our hypothesis by reviewing neuroimaging as well as neuropsychological studies on linguistic and musical syntax. The CHC hypothesis makes a set of novel testable predictions to guide future work on the relationship between language and music.