Caroline H. S. Barwood

Consensus Paper: Language and the Cerebellum: an Ongoing Enigma

In less than three decades, the concept “cerebellar neurocognition” has evolved from a mere afterthought to an entirely new and multifaceted area of neuroscientific research. A close interplay between three main strands of contemporary neuroscience induced a substantial modification of the traditional view of the cerebellum as a mere coordinator of autonomic and somatic motor functions. Indeed, the wealth of current evidence derived from detailed neuroanatomical investigations, functional neuroimaging studies with healthy subjects and patients and in-depth neuropsychological assessment of patients with cerebellar disorders shows that the cerebellum has a cardinal role to play in affective regulation, cognitive processing, and linguistic function. Although considerable progress has been made in models of cerebellar function, controversy remains regarding the exact role of the “linguistic cerebellum” in a broad variety of nonmotor language processes. This consensus paper brings together a range of different viewpoints and opinions regarding the contribution of the cerebellum to language function. Recent developments and insights in the nonmotor modulatory role of the cerebellum in language and some related disorders will be discussed. The role of the cerebellum in speech and language perception, in motor speech planning including apraxia of speech, in verbal working memory, in phonological and semantic verbal fluency, in syntax processing, in the dynamics of language production, in reading and in writing will be addressed. In addition, the functional topography of the linguistic cerebellum and the contribution of the deep nuclei to linguistic function will be briefly discussed. As such, a framework for debate and discussion will be offered in this consensus paper.

Improved language performance subsequent to low-frequency rTMS in patients with chronic non-fluent aphasia post-stroke

Background:  Low‐frequency repetitive transcranial magnetic stimulation (rTMS) has emerged as a potential tool for neurorehabilitation and remediation of language in chronic non‐fluent aphasia post‐stroke. Inhibitory (1 Hz) rTMS has been applied to homologous language sites to facilitate behavioural language changes. Improvements in picture‐naming performance and speech output over time have been reported.

Improved receptive and expressive language abilities in nonfluent aphasic stroke patients after application of rTMS: An open protocol case series

BACKGROUND Repetitive transcranial magnetic stimulation (rTMS) has been identified as a potentially valuable tool for the rehabilitation of language impairment after left hemisphere (LH) stroke, in populations of persons with chronic aphasia. Applied to a homologue to Brocas area, rTMS is posited to modulate bilateral language networks, promoting measurable behavioral language change, in accordance with theories of transcallosal disinhibition arising from the damaged LH. OBJECTIVE/HYPOTHESIS The current investigation is an open-label study, presenting detailed case and group presentations on a population of seven nonfluent aphasic participants. Behavioral language performance is presented on expressive and receptive language measures up to 8 months after a 10-day protocol of 1 Hz stimulation. This research aims to provide longitudinal behavioral language outcomes for persons with aphasia, subsequent to rTMS and supplement previous studies to inform the clinical efficacy of rTMS. RESULTS In accordance with previous investigations, significant improvements in picture naming, spontaneous elicited speech and auditory comprehension were found. Time of testing was identified as a significant main effect. Significant improvements in picture naming accuracy and decreases in picture naming latency were also identified. The results demonstrate sustained language improvements up to 8 months subsequent to TMS application. CONCLUSIONS The results of this investigation are consistent with the findings of previous research studies, reporting behavioral language changes after rTMS in nonfluent aphasia. Additional evidence is provided to demonstrate that rTMS may facilitate retrieval mechanisms involved in picture naming.

Modulation of N400 in chronic non-fluent aphasia using low frequency Repetitive Transcranial Magnetic Stimulation (rTMS)

Low frequency Repetitive Transcranial Magnetic Stimulation (rTMS) has previously been applied to language homologues in non-fluent populations of persons with aphasia yielding significant improvements in behavioral language function up to 43 months post stimulation. The present study aimed to investigate the electrophysiological correlates associated with the application of rTMS through measurement of the semantic based N400 Event-related brain potentials (ERP) component. Low frequency (1 Hz) rTMS was applied to the anterior portion of the homologue to Brocas area (pars triangularis), for 20 min per day for 10 days, using a stereotactic neuronavigational system. Twelve non-fluent persons with aphasia, 2-6 years post stroke were stimulated. Six participants were randomly assigned to receive real stimulation and six participants were randomly assigned to receive a blind sham control condition. ERP measures were recorded at baseline, 1 week and 2 months subsequent to stimulation. The findings demonstrate treatment related changes observed in the stimulation group when compared to the placebo control group at 2 months post stimulation indicating neuromodulation of N400 as a result of rTMS. No treatment related changes were identified in the stimulation group, when compared to the sham group from baseline to 1 week post stimulation. The electrophysiological results represent the capacity of rTMS to modulate neural language networks and measures of lexical-semantic function in participants with non-fluent aphasia and suggest that time may be an important factor in brain reorganization subsequent to rTMS.

Long term language recovery subsequent to low frequency rTMS in chronic non-fluent aphasia

BACKGROUND Repetitive transcranial magnetic stimulation (rTMS) has emerged as a potential therapeutic tool for the rehabilitation of language in chronic non-fluent aphasia post-stroke. Previous studies report that low frequency (1 Hz) rTMS applied to homologous language sites can facilitate behavioural language changes. Improvements in picture naming performance and speech output are frequently reported. OBJECTIVES This study aims to assess the efficacy of inhibitory rTMS to modulate language performance in non-fluent aphasia. METHODS Low-frequency (1 Hz) rTMS was applied to six active stimulation and six placebo patients for 20 min per day over 10 days, as outlined in a previous published investigation. Behavioural language outcome measures were taken at baseline (pre-stimulation) and 1 week, 2 months, 8 months and 12 months post-stimulation. RESULTS The findings demonstrate treatment-related changes observed in the stimulation group, up to 12 months post-stimulation, when compared to the placebo control group over time for naming performance, expressive language and auditory comprehension. CONCLUSION These outcomes provide considerable evidence to support the theory of rTMS modulating mechanisms of transcallosal disinhibition in the aphasic brain, and highlight the potential clinical application of rTMS for language rehabilitation in chronic aphasia.

Treatment of articulatory dysfunction in Parkinson's disease using repetitive transcranial magnetic stimulation.

Background and purpose:  Neuroimaging has demonstrated that improved speech outcomes in Parkinson’s Disease (PD) subsequent to behavioural treatment approaches are associated with increased activity in the motor and pre‐motor cortex. High‐frequency repetitive transcranial magnetic stimulation (rTMS) is capable of modulating cortical activity and has been reported to have significant benefit to general motor function in PD. It is possible that high‐frequency rTMS may also have beneficial outcomes on speech production in PD.

Communicatively accessible public transport for people with aphasia: A pilot study

Background: There has been little research as to how society accommodates the communicative needs of people with aphasia. The accessibility of public transport becomes important post stroke and good communication skills are vital for successful travel. Aims: This pilot study aims to identify the communicative barriers and facilitators that exist when people with aphasia use public transport. Methods & Procedures: The qualitative study used in‐depth, semi‐structured interviews and observations with seven participants who presented with mild‐moderate aphasia. Interviews were conducted pre‐ and post‐journey. Observations were conducted throughout the journey chain, from planning the trip to arrival at destination. Outcomes & Results: The most significant barriers to a public transport journey were within the category of Public Transport Services and Systems, most notably during transactions requiring verbal expression and where time constraints were at a premium. The most common facilitators were in the categories of Products and Technology for Communication (e.g., written materials) and Support from Other People. Conclusion: These findings suggest that the majority of communicative barriers for commuters with aphasia occur in circumstances when verbal communication is mandatory, or when rapid information processing is required. Additionally, people with aphasia employ many communicative facilitators. These have enabled them to travel successfully and need to be promoted to new users of public transport systems. This study highlights the need to address communicative aspects of accessibility within public transport systems.

Non-invasive brain stimulation: A new frontier in the treatment of neurogenic speech-language disorders

Abstract There is a growing body of evidence to support the use of non-invasive brain stimulation techniques such as transcranial magnetic stimulation (TMS) and transcranial direct current stimulation (tDCS) for the treatment of acquired speech and language disorders. The aim of the present paper is to review evidence to support the use of these procedures in the treatment of aphasia and dysarthria. Both TMS and tDCS are described in terms of their underlying principles and biophysics and their relative advantages and disadvantages for rehabilitation of acquired neurogenic communication disorders. Several studies have documented positive effects of inhibitory repetitive TMS (rTMS) to right Brocas area homologue on language recovery in non-fluent aphasia post-stroke. Improved language outcomes subsequent to high frequency rTMS applied to the lesioned hemisphere have also been documented. Similarly, therapeutic benefits have also been reported following tDCS, although the findings are less consistent than is the case with rTMS. Improved articulatory function and speech intelligibility has been noted in response to stimulation with excitatory rTMS in Parkinsons disease. It is suggested that the use of brain stimulation techniques in combination with more traditional therapies may represent the most innovative future approach to the treatment of acquired communication disorders.

rTMS as a treatment for neurogenic communication and swallowing disorders

Recent years have seen the introduction of non‐invasive brain stimulation techniques (e.g. transcranial direct current stimulation and transcranial magnetic stimulation) utilized to target neural‐based pathologies, for therapeutic gain. The direct manipulation of cortical brain activity by repetitive transcranial magnetic stimulation (rTMS) could potentially serve as an efficacious complimentary rehabilitatory treatment for speech, language and swallowing disorders of a neurological origin. The high prevalence of positive reports on communication and swallowing outcomes support these premises. Nonetheless, experimental evidence to date in some areas is considered rudimentary and is deficient in providing placebo‐controlled substantiation of longitudinal neuroplastic change subsequent to stimulation. The most affirmative therapeutic responses have arisen from small placebo‐controlled trials using low‐frequency rTMS for patients with non‐fluent aphasia and high‐frequency rTMS applied to individuals with Parkinsons disease to improve motor speech performance and outcomes. Preliminary studies applying rTMS to ameliorate dysphagic symptoms post‐stroke provide positive swallowing outcomes for patients. Further research into the optimization of rTMS protocols, including dosage, stimulation targets for maximal efficacy and placebo techniques, is critically needed to provide a fundamental basis for clinical interventions using this technique. rTMS represents a highly promising and clinically relevant technique, warranting the future development of clinical trials across a spectrum of communication and swallowing pathologies, to substantiate and expand on the methods outlined in published reports.

Longitudinal modulation of N400 in chronic non-fluent aphasia using low-frequency rTMS: A randomised placebo controlled trial

Background: Measurements of the lexical-semantic ERP component N400 have been used to monitor neurophysiological change associated with repetitive transcranial magnetic simulation (rTMS) in persons with chronic non-fluent aphasia. Combined with reported favourable behavioural language changes, research evidence has informed the potential of rTMS to assist brain reorganisation patterns in persons with chronic language impairment. Aims: The present study aimed to provide evidence regarding the longitudinal effects of rTMS on N400, an ERP measure of lexical-semantic performance in persons with non-fluent aphasia. Further, it aimed to provide a comparison of N400 responses between the active and placebo group across semantically congruent and incongruent ERP conditions. Methods & Procedures: A total of 12 persons with aphasia were randomly assigned to receive active stimulation (n = 6) or placebo stimulation (n = 6). ERP measures from four centro-parietal electrodes were taken at baseline, 1 week, 2 months, 8 months, and 12 months post stimulation. Outcomes & Results: Significant interactions of group × time were identified for task performance between the active and placebo groups, where active performance was higher. Significant interaction effects of group × time × condition, for some electrodes across ERP measures of mean amplitude, peak amplitude, and area were found. Active group N400 responses improved (increased negativity) over 12 months, compared to the placebo group responses. Conclusions: The results demonstrated that modulation of N400 measures up to 12 months post rTMS for the active stimulation group was present. Electrophysiological changes were accompanied by improvements in anomaly detection over time. Overall, these findings highlight that low-frequency rTMS has the capacity to modulate lexical-semantic processing over time as evidenced via ERP measures.