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.

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.

Unravelling the influence of mild traumatic brain injury (MTBI) on cognitive-linguistic processing: a comparative group analysis.

BACKGROUND: Cognitive-linguistic deficits often accompany traumatic brain injury (TBI) and can negatively impact communicative competency. The linguistic sequelae underpinning mild TBI (MTBI) remain largely unexplored in contemporary literature. OBJECTIVES: The present research methods aim to provide group evidence pertaining to the influence of MTBI on linguistic and higher-level language processing. Extrapolating on the findings of recent case reports, it is hypothesized that performance of the MTBI patients will be significantly reduced compared to normal controls performance on the employed high-level linguistic tasks. METHODS: Sixteen patients with MTBI and 16 age- and education-matched normal control participants were assessed using a comprehensive battery of cognitive-linguistic assessments. RESULTS: The results demonstrated statistically significant differences between MTBI and normal control group performance across a number of higher-level linguistic, general cognitive and general language tasks. MTBI group performance was significantly lower than the normal control group on tasks requiring complex lexical semantic operations and memory demands, including: Recall, organization, making inferences, naming and perception/discrimination. CONCLUSIONS: These outcomes confer that post-MTBI, cognitive, high-level language and isolated general language performance (e.g. naming) is significantly reduced in MTBI patients, compared to normal controls. Furthermore, the detailed cognitive-linguistic profile offered provides a necessary direction for the identification of areas of linguistic decline in MTBI and targets for therapeutic intervention of impaired cognitive-linguistic processes to ultimately improve communicative outcomes in MTBI.

The effect of rTMS on auditory processing in adults with chronic, bilateral tinnitus: a placebo-controlled pilot study.

BACKGROUND: On the basis that tinnitus may result from neural hyperactivity in the auditory cortex, researchers have investigated the use of low frequency (1 Hz) repetitive transcranial magnetic stimulation (rTMS) as a potential modulator of this hyperactivity. While these investigations show promise, investigations to date have neglected to consider the possible effect of 1 Hz rTMS on other functions of the auditory cortex of these individuals, such as auditory processing. OBJECTIVE/HYPOTHESIS: This placebo-controlled pilot study aimed to determine whether 1 Hz rTMS applied to the primary auditory cortex (PAC), specifically Brodmann Area 41 (BA41), of adults with chronic, bilateral tinnitus would influence their auditory processing abilities. METHODS: Eight participants with bilateral, chronic tinnitus were randomized to receive a 10-day course of neuronavigationally guided active rTMS (n = 4) or placebo rTMS (n = 4) treatment applied to a focal region of the left PAC (BA41). Participants' auditory processing was measured using Time Compressed Reverberant Speech and three-pair Dichotic Digits (DD). Their tinnitus was measured using the Tinnitus Handicap Inventory (THI) and a psychoacoustic measure of tinnitus perception. All outcome measures were administered at baseline (1 week prior to rTMS), 1 week, 1, 2 and 3 months post-rTMS. RESULTS: All four participants in the active rTMS (A) group, and none of the participants in the sham (placebo) rTMS (S) group, showed improved auditory processing scores at multiple assessment points post-stimulation, with the group differences in median normalized gain scores reaching significance at the 5% level from 1 week or 1 month post-stimulation onwards. Three of the four participants in the active rTMS (A) group, and none of the participants in the sham rTMS (S) group, showed improved tinnitus scores at multiple assessment points post-stimulation, with some of the group differences in median normalized gain scores reaching significance at the 5% level. CONCLUSIONS: The results of this preliminary study suggest that 1 Hz rTMS applied to the PAC (BA41) has the capacity to improve both auditory processing and tinnitus perception in some adults with chronic, bilateral tinnitus.

Language abilities of patients with primary progressive multiple sclerosis: A preliminary group and case investigation.

Language impairments are reported in multiple sclerosis (MS). To date, the majority of studies have evaluated language differences between relapsing-remitting (RR) and chronic progressive (CP) clinical courses. Neurologists have distinguished two progressive courses of MS: primary progressive (PP) MS and secondary progressive (SP) MS. Recent evidence suggests that cognitive performance profiles may provide a means of differentiating between the clinical courses of RR, SP, and PPMS. With this in mind, a deviation of language profiles between sub-types is predicted. The purpose of this study is to profile the language abilities of five participants with PPMS. Five participants with PPMS participated in this investigation. The participants were assessed using the Neurosensory Center Comprehensive Examination for Aphasia (NCCEA), the Boston Naming Test (BNT), and the Test of Language Competence-Expanded (TLC-E). Data analysis consisted of (a) comparison of the total scores achieved by the PPMS participants and a group of 26 age-matched controls on the NCCEA, BNT, and TLC-E, and (b) case studies to individually profile the language abilities of the five participants with PPMS. Comparison of the NCCEA, BNT, and TLC-E total scores of the participants with PPMS and the control group did not indicate significant differences between the two groups. Case-by-case analysis revealed deficits in meta-linguistic abilities in two participants. The results provide preliminary evidence to suggest that, although patients with PPMS may have preserved general language abilities, some individuals may present with mild impairments in high-level linguistic abilities.

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

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 Broca's 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 Parkinson's 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.

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 Broca's 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.

The effects of low frequency Repetitive Transcranial Magnetic Stimulation (rTMS) and sham condition rTMS on behavioural language in chronic non-fluent aphasia: Short term outcomes.

INTRODUCTION: The application of low frequency (1 Hz) Repetitive Transcranial Magnetic Stimulation (rTMS) to right hemisphere (RH) language homologues in non-fluent aphasic populations has yielded improvements in behavioural language function, up to 43 months post stimulation. Functional imaging studies have demonstrated RH language homologue "overactivation" post left inferior frontal gyrus (IFG) damage, in chronic non-fluent aphasia. The effects of low frequency (inhibitory) rTMS are postulated to be as a result of a reduction of overactivation in RH language homologues, facilitating the reorganisation of neural language networks. METHODS: Low frequency (1 Hz) rTMS was applied to the anterior portion of a Broca's area homologue (pars triangularis), for 20 minutes per day for 10 days, using a stereotactic neuronavigational system. Twelve non-fluent aphasic patients (six real stimulation and six sham), 2-10 years post stroke were stimulated. Behavioural language outcome measures were taken at baseline and 1 week post rTMS. RESULTS: Comparisons between the real stimulation and sham conditions indicated significant main effects between the stimulation and sham groups to 1 week post stimulation for naming accuracy, latency and repetition. CONCLUSIONS: This study indicates that rTMS has the capacity to modulate neural language networks, to facilitate improvements in behavioural language function, 1 week post TMS.

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 Broca's 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.