Direct cortical stimulation of inferior frontal cortex disrupts both speech and music production in highly trained musicians

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.

IDEAL monitoring of musical skills during awake craniotomy: From step 1 to step 2

The aim of awake brain surgery is to perform a maximum resection on the one hand, and to preserve cognitive functions, quality of life and personal autonomy on the other hand. Historically, language and sensorimotor functions were most frequently monitored. Over the years other cognitive functions, including music, have entered the operation theatre. Cases about monitoring musical abilities during awake brain surgery are emerging, and a systematic method how to monitor music would be the next step. According to the IDEAL framework for surgical innovations our study aims to present future recommendation based on a systematic literature search (PRISMA) in combination with lessons learned from three case reports from our own clinical practice with professional musicians (n = 3). We plead for structured procedures including individual tailored tasks. By embracing these recommendations, we can both improve clinical care and unravel music functions in the brain.

Intraoperative cortical localization of music and language reveals signatures of structural complexity in posterior temporal cortex

Language and music involve the productive combination of basic units into structures. It remains unclear whether brain regions sensitive to linguistic and musical structure are co-localized. We report an intraoperative awake craniotomy in which a left-hemispheric language-dominant professional musician underwent cortical stimulation mapping (CSM) and electrocorticography of music and language perception and production during repetition tasks. Musical sequences were melodic or amelodic, and differed in algorithmic compressibility (Lempel-Ziv complexity). Auditory recordings of sentences differed in syntactic complexity (single vs. multiple phrasal embeddings). CSM of posterior superior temporal gyrus (pSTG) disrupted music perception and production, along with speech production. pSTG and posterior middle temporal gyrus (pMTG) activated for language and music (broadband gamma; 70-150 Hz). pMTG activity was modulated by musical complexity, while pSTG activity was modulated by syntactic complexity. This points to shared resources for music and language comprehension, but distinct neural signatures for the processing of domain-specific structural features.

More Evidence That Ensemble Music Training Influences Children's Neurobehavioral Correlates of Auditory Executive Attention

We assessed the neurocognitive correlates of auditory executive attention in low socioeconomic status 9-12-year-old children-with and without training in a social music program (OrKidstra). Event-related potentials (ERPs) were recorded during an auditory Go/NoGo task utilizing 1100 Hz and 2000 Hz pure tones. We examined Go trials, which required attention, tone discrimination and executive response control. We measured Reaction Times (RTs), accuracy and amplitude of relevant ERP signatures: N100-N200 complex, P300, and Late Potentials (LP). Children also completed a screening test for auditory sensory sensitivity and the Peabody Picture Vocabulary Test (PPVT-IV) to assess verbal comprehension. OrKidstra children had faster RTs and larger ERP amplitudes to the Go tone. Specifically, compared to their comparison counterparts, they showed more negative-going polarities bilaterally for N1-N2 and LP signatures across the scalp and larger P300s in parietal and right temporal electrodes; some enhancements were lateralized (i.e., left frontal, and right central and parietal electrodes). Because auditory screening yielded no between-group differences, results suggest that music training did not enhance sensory processing but perceptual and attentional skills, possibly shifting from top-down to more bottom-up processes. Findings have implications for socially based music training interventions in school, specifically for socioeconomically disadvantaged children.

Awake Craniotomy and Intraoperative Musical Performance for Brain Tumor Surgery: Case Report and Literature Review

Music experience and creation is a complex phenomenon that involves multiple brain structures. Music mapping during awake brain surgery, in addition to standard speech and motor mapping, remains a controversial topic. Music function can be impaired selectively, despite overlap with other neural networks commonly tested during direct cortical stimulation. We describe the case of a 34-year-old male patient presenting with a glioma located within eloquent cortex, who is also a professional musician and actor. We performed an awake craniotomy (AC) that mapped the standard motor and speech areas, while the patient played guitar intraoperatively and sang. Outcomes were remarkable with preservation of function and noted improvements in his musical abilities in outpatient follow-up. In addition, we performed a review of the literature in which awake craniotomies were performed for the removal of brain tumors in patients with some background in music (e.g., score reading, humming/singing). To date, only 4 patients have played a musical instrument intraoperatively during an AC for brain tumor resection. Using awake cortical mapping techniques and paradigms for preserving speech function during an intraoperative musical performance with singing is feasible and can yield a great result for patients. The use of standard brain mapping over music processing mapping did not yield a negative outcome. More experience is needed to understand and standardize this procedure as the field of brain mapping continues to grow for tumor resections.

[Mapping the musician brain during awake craniotomy]

Direct cortical stimulation during awake craniotomy with speech testing became the «gold standard» in brain mapping and preserving speech zones during neurosurgical procedures. However, there are many other cerebral functions, and their loss can be very critical for certain patients. For example, such a function is production and perception of music for musicians. This review presents the latest data on functional anatomy of musician brain, as well as aspects of neurosurgical treatment with awake craniotomy and music testing under brain mapping.

A Neurosurgical Functional Dissection of the Middle Precentral Gyrus during Speech Production

Classical models have traditionally focused on the left posterior inferior frontal gyrus (Broca's area) as a key region for motor planning of speech production. However, converging evidence suggests that it is not critical for either speech motor planning or execution. Alternative cortical areas supporting high-level speech motor planning have yet to be defined. In this review, we focus on the precentral gyrus, whose role in speech production is often thought to be limited to lower-level articulatory muscle control. In particular, we highlight neurosurgical investigations that have shed light on a cortical region anatomically located near the midpoint of the precentral gyrus, hence called the middle precentral gyrus (midPrCG). The midPrCG is functionally located between dorsal hand and ventral orofacial cortical representations and exhibits unique sensorimotor and multisensory functions relevant for speech processing. This includes motor control of the larynx, auditory processing, as well as a role in reading and writing. Furthermore, direct electrical stimulation of midPrCG can evoke complex movements, such as vocalization, and selective injury can cause deficits in verbal fluency, such as pure apraxia of speech. Based on these findings, we propose that midPrCG is essential to phonological-motoric aspects of speech production, especially syllabic-level speech sequencing, a role traditionally ascribed to Broca's area. The midPrCG is a cortical brain area that should be included in contemporary models of speech production with a unique role in speech motor planning and execution.

Different Music Training Modulates Theta Brain Oscillations Associated with Executive Function

Different music training involves different hand coordination levels and may have a significant influence on brain oscillation for the executive function. However, few research has focused on the plasticity of executive function and the brain oscillation modulated by different musical instrument training modules. In this study, we recruited 18 string musicians, 20 pianists, and 19 non-musicians to perform a bimanual key pressing task during EEG recording. Behavioral results revealed that pianists have the highest accuracy and the shortest response time, followed by string musicians and non-musicians (p < 0.05). Time-frequency analyses of EEG revealed that pianists generated significantly greater theta power than the other groups from 500 ms to 800 ms post-stimulus in mid-central, frontal brain areas, and motor control areas. Functional connectivity analyses found that the pianists showed significantly greater connectivity in the frontal-parietal area in theta band based on phase-locking value analysis, which suggests that piano training improves executive function and enhances the connectivity between prefrontal and mid-central regions. These findings contribute to a better understanding of the effects of different music training on executive function.

Effects of traditional Cantonese opera songs on Cantonese-speaking, community-dwelling older adults' cognitive and psychological function, well-being, and health

Objectives: Experiencing multi-sensory cognitive stimulation through the enjoyment of Cantonese opera songs, with their lively rhythms, familiar folk tales, meaningful lyrics and pleasant scenarios, has the potential to increase neuroplasticity and prevent cognitive decline.Methods: This prospective pre- and post-test quasi-experimental randomised controlled trial design study aimed to explore the social benefits of older adults' active participation in practising Cantonese opera songs as compared with passive participation (as an audience) and a non-interventional control group on cognitive function psychological function, functional independence, well-being and health.Results: By recruiting a group of older adults who were receiving day activities social service in Hong Kong. Thirty participants were randomly allocated to active participation in Cantonese opera (ACO). They participated in practising Cantonese opera songs. Thirty-four participants were assigned to passive participation in Cantonese opera (PCO). They received passive intervention by listening to and appreciating the opera songs as a social event. Thirty-one participants were used as a control group and received no similar training. (Results) ACO caused a positive change in cognitive function as compared to PCO and to no intervention, which implies that active learning and practise of opera songs benefits global cognitive function. The psychological function of the participants in the PCO group showed an elevated positive affect and a reduced negative affect. A statistically significant difference was noted in the time effect among the physical domains of health status, functional independence and well-being of participants who underwent Cantonese opera intervention.

Efficacy of transcranial Direct Current Stimulation (tDCS) combined with intensive speech therapy for language production in monozygotic twins with corpus callosum dysgenesis (CCD): A sham-controlled single subject study

The purpose of this single subject study was to investigate whether transcranial direct current stimulation (tDCS) applied to both hemispheres combined with speech therapy can improve language learning in a pair of 5-year-old twins with corpus callosum dysgenesis (CCD). The treatment protocol included anodal tDCS with simultaneous speech therapy in one of the participants (T.D.), and sham-tDCS with the same montage, and stimulation regime concomitant with speech therapy for the other twin (A.D.). Our findings show that T.D. improved in language production when treated with speech therapy in combination with tDCS. A.D. showed evidence for a relatively minor behavioral benefit from speech therapy.

Musicality in human vocal communication: an evolutionary perspective

Studies show that specific vocal modulations, akin to those of infant-directed speech (IDS) and perhaps music, play a role in communicating intentions and mental states during human social interaction. Based on this, we propose a model for the evolution of musicality-the capacity to process musical information-in relation to human vocal communication. We suggest that a complex social environment, with strong social bonds, promoted the appearance of musicality-related abilities. These social bonds were not limited to those between offspring and mothers or other carers, although these may have been especially influential in view of altriciality of human infants. The model can be further tested in other species by comparing levels of sociality and complexity of vocal communication. By integrating several theories, our model presents a radically different view of musicality, not limited to specifically musical scenarios, but one in which this capacity originally evolved to aid parent-infant communication and bonding, and even today plays a role not only in music but also in IDS, as well as in some adult-directed speech contexts. This article is part of the theme issue 'Voice modulation: from origin and mechanism to social impact (Part II)'.

The feasibility and added value of mapping music during awake craniotomy: A systematic review

The value of mapping musical function during awake craniotomy is unclear. Hence, this systematic review was conducted to examine the feasibility and added value of music mapping in patients undergoing awake craniotomy. An extensive search, on 26 March 2021, in four electronic databases (Medline, Embase, Web of Science and Cochrane CENTRAL register of trials), using synonyms of the words "Awake Craniotomy" and "Music Performance," was conducted. Patients performing music while undergoing awake craniotomy were independently included by two reviewers. This search resulted in 10 studies and 14 patients. Intra-operative mapping of musical function was successful in 13 out of 14 patients. Isolated music disruption, defined as disruption during music tasks with intact language/speech and/or motor functions, was identified in two patients in the right superior temporal gyrus, one patient in the right and one patient in the left middle frontal gyrus and one patient in the left medial temporal gyrus. Pre-operative functional MRI confirmed these localizations in three patients. Assessment of post-operative musical function, only conducted in seven patients by means of standardized (57%) and non-standardized (43%) tools, report no loss of musical function. With these results, we conclude that mapping music is feasible during awake craniotomy. Moreover, we identified certain brain regions relevant for music production and detected no decline during follow-up, suggesting an added value of mapping musicality during awake craniotomy. A systematic approach to map musicality should be implemented, to improve current knowledge on the added value of mapping musicality during awake craniotomy.

Functional MRI of Native and Non-native Speech Sound Production in Sequential German-English Bilinguals

Bilingualism and multilingualism are highly prevalent. Non-invasive brain imaging has been used to study the neural correlates of native and non-native speech and language production, mainly on the lexical and syntactic level. Here, we acquired continuous fast event-related FMRI during visually cued overt production of exclusively German and English vowels and syllables. We analyzed data from 13 university students, native speakers of German and sequential English bilinguals. The production of non-native English sounds was associated with increased activity of the left primary sensorimotor cortex, bilateral cerebellar hemispheres (lobule VI), left inferior frontal gyrus, and left anterior insula compared to native German sounds. The contrast German > English sounds was not statistically significant. Our results emphasize that the production of non-native speech requires additional neural resources already on a basic phonological level in sequential bilinguals.

Two cortical representations of voice control are differentially involved in speech fluency

Recent studies have identified two distinct cortical representations of voice control in humans, the ventral and the dorsal laryngeal motor cortex. Strikingly, while persistent developmental stuttering has been linked to a white-matter deficit in the ventral laryngeal motor cortex, intensive fluency-shaping intervention modulated the functional connectivity of the dorsal laryngeal motor cortical network. Currently, it is unknown whether the underlying structural network organization of these two laryngeal representations is distinct or differently shaped by stuttering intervention. Using probabilistic diffusion tractography in 22 individuals who stutter and participated in a fluency shaping intervention, in 18 individuals who stutter and did not participate in the intervention and in 28 control participants, we here compare structural networks of the dorsal laryngeal motor cortex and the ventral laryngeal motor cortex and test intervention-related white-matter changes. We show (i) that all participants have weaker ventral laryngeal motor cortex connections compared to the dorsal laryngeal motor cortex network, regardless of speech fluency, (ii) connections of the ventral laryngeal motor cortex were stronger in fluent speakers, (iii) the connectivity profile of the ventral laryngeal motor cortex predicted stuttering severity (iv) but the ventral laryngeal motor cortex network is resistant to a fluency shaping intervention. Our findings substantiate a weaker structural organization of the ventral laryngeal motor cortical network in developmental stuttering and imply that assisted recovery supports neural compensation rather than normalization. Moreover, the resulting dissociation provides evidence for functionally segregated roles of the ventral laryngeal motor cortical and dorsal laryngeal motor cortical networks.

Awake intraoperative mapping to identify cortical regions related to music performance: Technical note

The aim of this manuscript is to present our intraoperative technique assessing the ability to perform music. Our protocol excludes cases where performance can be disrupted by motor deficits. The positive cortical sites (the posterior part of the superior temporal gyrus and supramarginal gyrus) related purely to music performance are also reported. We present the case of a patient, an amateur piano player who underwent surgery for a symptomatic supratentorial cavernoma while awake with intraoperative brain mapping. This case report shows that amateur and possibly professional musicians may benefit from awake procedures. This report confirms that stimulation of the specific area of the brain can disturb the function of a large network responsible for high-level cognitive task, like music performance.

Cortical Encoding of Manual Articulatory and Linguistic Features in American Sign Language

The fluent production of a signed language requires exquisite coordination of sensory, motor, and cognitive processes. Similar to speech production, language produced with the hands by fluent signers appears effortless but reflects the precise coordination of both large-scale and local cortical networks. The organization and representational structure of sensorimotor features underlying sign language phonology in these networks remains unknown. Here, we present a unique case study of high-density electrocorticography (ECoG) recordings from the cortical surface of profoundly deaf signer during awake craniotomy. While neural activity was recorded from sensorimotor cortex, the participant produced a large variety of movements in linguistic and transitional movement contexts. We found that at both single electrode and neural population levels, high-gamma activity reflected tuning for particular hand, arm, and face movements, which were organized along dimensions that are relevant for phonology in sign language. Decoding of manual articulatory features revealed a clear functional organization and population dynamics for these highly practiced movements. Furthermore, neural activity clearly differentiated linguistic and transitional movements, demonstrating encoding of language-relevant articulatory features. These results provide a novel and unique view of the fine-scale dynamics of complex and meaningful sensorimotor actions.

Direct electrical stimulation mapping of cognitive functions in the human brain

Direct electrical stimulation (DES) is a well-established clinical tool for mapping cognitive functions while patients are undergoing awake neurosurgery or invasive long-term monitoring to identify epileptogenic tissue. Despite the proliferation of a range of invasive and noninvasive methods for mapping sensory, motor and cognitive processes in the human brain, DES remains the clinical gold standard for establishing the margins of brain tissue that can be safely removed while avoiding long-term neurological deficits. In parallel, and principally over the last two decades, DES has emerged as a powerful scientific tool for testing hypotheses of brain organization and mechanistic hypotheses of cognitive function. DES can cause transient "lesions" and thus can support causal inferences about the necessity of stimulated brain regions for specific functions, as well as the separability of sensory, motor and cognitive processes. This Special Issue of Cognitive Neuropsychology emphasizes the use of DES as a research tool to advance understanding of normal brain organization and function.

Awake Mapping of the Auditory Cortex during Tumor Resection in an Aspiring Musical Performer: A Case Report

INTRODUCTION

Preoperative functional MRI (fMRI) and intraoperative awake cortical mapping are established strategies to identify and preserve critical language structures during neurosurgery. There is growing appreciation for the need to similarly identify and preserve eloquent tissue critical for music production.

CASE REPORT

A 19-year-old female musician, with a 3- to 4-year history of events concerning for musicogenic seizures, was found to have a right posterior temporal tumor, concerning for a low-grade glial neoplasm. Preoperative fMRI assessing passive and active musical tasks localized areas of activation directly adjacent to the tumor margin. Cortical stimulation during various musical tasks did not identify eloquent tissue near the surgical site. A gross total tumor resection was achieved without disruption of singing ability. At 9-month follow-up, the patient continued to have preserved musical ability with full resolution of seizures and without evidence of residual lesion or recurrence.

CONCLUSION

A novel strategy for performing an awake craniotomy, incorporating preoperative fMRI data for music processing with intraoperative cortical stimulation, interpreted with the assistance of a musician expert and facilitated gross total resection of the patient's tumor without comprising her musical abilities.

Attention/memory complaint is correlated with motor speech disorder in Parkinson's disease

BACKGROUND

The mechanisms underlying the online modulation of motor speech in Parkinson's disease (PD) have not been determined. Moreover, medical and rehabilitation interventions for PD-associated motor speech disorder (MSD) have a poor long-term prognosis.

METHODS

To compare risk factors in PD patients with MSD to those without MSD (non-MSD) and determine predictive independent risk factors correlated with the MSD phenotype, we enrolled 314 PD patients, including 250 with and 64 without MSD. We compared demographic, characteristic data, as well as PD-associated evaluations between the MSD group and non-MSD group.

RESULTS

Univariate analysis showed that demographic characteristics, including occupation, educational level, monthly income and speaking background; clinical characteristics, including lesions in the frontal and temporal lobes, and concurrent dysphagia; and PD-associated evaluations, including the activity of daily living (ADL) score, non-motor symptoms scale (NMSS) domain 4 score (perceptual problem), and NMSS domain 5 score (attention/memory) were all significantly different between the MSD and non-MSD group (all P < 0.05). Multivariate logistic regression analysis showed that educational level, frontal lesions, and NMSS domain 5 score (attention/memory) were independent risk factors for PD-associated MSD (all P < 0.005).

CONCLUSIONS

We determined an association between MSD phenotype and cognitive impairment, reflected by low-level education and related clinical profiles. Moreover, attention and memory dysfunction may play key roles in the progression of MSD in PD patients. Further studies are required to detail the mechanism underlying abnormal speech motor modulation in PD patients. Early cognitive intervention may enhance rehabilitation management and motor speech function in patients with PD-associated MSD.

How is electrical stimulation of the brain experienced, and how can we tell? Selected considerations on sensorimotor function and speech

Electrical stimulation of the nervous system is a powerful tool for localizing and examining the function of numerous brain regions. Delivered to certain regions of the cerebral cortex, electrical stimulation can evoke a variety of first-order effects, including observable movements or an urge to move, or somatosensory, visual, or auditory percepts. In still other regions the subject may be oblivious to the stimulation. Often overlooked, however, is whether the subject is aware of the stimulation, and if so, how the stimulation is experienced by the subject. In this review of how electrical stimulation has been used to study selected aspects of sensorimotor and language function, we raise questions that future studies might address concerning the subjects' second-order experiences of intention and agency regarding evoked movements, of the naturalness of evoked sensory percepts, and of other qualia that might be evoked in the absence of an overt first-order experience.

Direct electrical stimulation of the left frontal aslant tract disrupts sentence planning without affecting articulation

Sentence production involves mapping from deep structures that specify meaning and thematic roles to surface structures that specify the order and sequencing of production ready elements. We propose that the frontal aslant tract is a key pathway for sequencing complex actions with deep hierarchical structure. In the domain of language, and primarily with respect to the left FAT, we refer to this as the 'Syntagmatic Constraints On Positional Elements' (SCOPE) hypothesis. One prediction made by the SCOPE hypothesis is that disruption of the frontal aslant tract should disrupt sentence production at grammatical phrase boundaries, with no disruption of articulatory processes.  We test this prediction in a patient undergoing direct electrical stimulation mapping of the frontal aslant tract during an awake craniotomy to remove a left frontal brain tumor. We found that stimulation of the left FAT prolonged inter-word durations at the start of grammatical phrases, while inter-word durations internal to noun phrases were unaffected, and there was no effect on intra-word articulatory duration. These results provide initial support for the SCOPE hypothesis, and motivate novel directions for future research to explore the functions of this recently discovered component of the language system.

Inhibition of Manual Movements at Speech Arrest Sites in the Posterior Inferior Frontal Lobe

BACKGROUND

Intraoperative stimulation of the posterior inferior frontal lobe (IFL) induces speech arrest, which is often interpreted as demonstration of essential language function. However, prior reports have described “negative motor areas” in the IFL, sites where stimulation halts ongoing limb motor activity.

OBJECTIVE

To investigate the spatial and functional relationship between IFL speech arrest areas and negative motor areas (NMAs).

METHODS

In this retrospective cohort study, intraoperative stimulation mapping was performed to localize speech and motor function, as well as arrest of hand movement, hand posture, and guitar playing in a set of patients undergoing awake craniotomy for dominant hemisphere pathologies. The incidence and localization of speech arrest and motor inhibition was analyzed.

RESULTS

Eleven patients underwent intraoperative localization of speech arrest sites and inhibitory motor areas. A total of 17 speech arrest sites were identified in the dominant frontal lobe, and, of these, 5 sites (29.4%) were also identified as NMAs. Speech arrest and arrest of guitar playing was also evoked by a single IFL site in 1 subject.

CONCLUSION

Inferior frontal gyrus speech arrest sites do not function solely in speech production. These findings provide further evidence for the complexity of language organization, and suggest the need for refined mapping strategies that discern between language-specific sites and inhibitory motor areas.