Do People With Apraxia of Speech and Aphasia Improve or Worsen Across Repeated Sequential Word Trials?

PURPOSE: During motor speech examinations for suspected apraxia of speech (AOS), clients are routinely asked to repeat words several times sequentially. The purpose of this study was to understand the task in terms of the relationship among consecutive attempts. We asked to what extent phonemic accuracy changes across trials and whether the change is predicted by AOS diagnosis and sound production severity. METHOD: One hundred thirty-three participants were assigned to four diagnostic groups based on quantitative metrics (aphasia plus AOS, aphasia-only, and aphasia with two borderline speech profiles). Each participant produced four multisyllabic words 5 times consecutively. These productions were audio-recorded and transcribed phonetically and then summarized as the proportion of target phonemes that was produced accurately. Nonparametric statistics were used to analyze percent change in accuracy from the first to the last production based on diagnostic group and a broad measure of speech sound accuracy. RESULTS: Accuracy on the repeated words deteriorated across trials for all groups, showing reduced accuracy from the first to the last repetition for 62% of participants. Although diagnostic groups differed on the broad measure of speech sound accuracy, severity classification based on this measure did not determine degree of deterioration on the repeated words task. DISCUSSION: Responding to a request to say multisyllabic words 5 times sequentially is challenging for people with aphasia with and without AOS, and as such, performance is prone to errors even with mild impairment. For most, the task does not encourage self-correction. Instead, it promotes errors, regardless of diagnosis, and is, therefore, useful for screening purposes.

Articulation Rate, Pauses, and Disfluencies in Professional Fighters: Potential Speech Biomarkers for Repetitive Head Injury.

OBJECTIVE: As part of a larger study dedicated to identifying speech and language biomarkers of neurological decline associated with repetitive head injury (RHI) in professional boxers and mixed martial artists (MMAs), we examined articulation rate, pausing, and disfluency in passages read aloud by participants in the Professional Athletes Brain Health Study. SETTING: A large outpatient medical center specializing in neurological care. PARTICIPANTS, DESIGN, AND MAIN MEASURES: Passages read aloud by 60 boxers, 40 MMAs, and 55 controls were acoustically analyzed to determine articulation rate (the number of syllables produced per second), number and duration of pauses, and number and duration of disfluencies in this observational study. RESULTS: Both boxers and MMAs differed from controls in articulation rate, producing syllables at a slower rate than controls by nearly half a syllable per second on average. Boxers produced significantly more pauses and disfluencies in passages read aloud than MMAs and controls. CONCLUSIONS: Slower articulation rate in both boxers and MMA fighters compared with individuals with no history of RHI and the increased occurrence of pauses and disfluencies in the speech of boxers suggest changes in speech motor behavior that may relate to RHI. These speech characteristics can be measured in everyday speaking conditions and by automatic recognition systems, so they have the potential to serve as effective, noninvasive clinical indicators for RHI-associated neurological decline.

Transcranial direct current stimulation modulates working memory and prefrontal-insula connectivity after mild-moderate traumatic brain injury.

Background: Persistent posttraumatic symptoms (PPS) may manifest after a mild-moderate traumatic brain injury (mmTBI) even when standard brain imaging appears normal. Transcranial direct current stimulation (tDCS) represents a promising treatment that may ameliorate pathophysiological processes contributing to PPS. Objective/Hypothesis: We hypothesized that in a mmTBI population, active tDCS combined with training would result in greater improvement in executive functions and post-TBI cognitive symptoms and increased resting state connectivity of the stimulated region, i.e., left dorsolateral prefrontal cortex (DLPFC) compared to control tDCS. Methods: Thirty-four subjects with mmTBI underwent baseline assessments of demographics, symptoms, and cognitive function as well as resting state functional magnetic resonance imaging (rsfMRI) in a subset of patients (n = 24). Primary outcome measures included NIH EXAMINER composite scores, and the Neurobehavioral Symptom Inventory (NSI). All participants received 10 daily sessions of 30 min of executive function training coupled with active or control tDCS (2 mA, anode F3, cathode right deltoid). Imaging and assessments were re-obtained after the final training session, and assessments were repeated after 1 month. Mixed-models linear regression and repeated measures analyses of variance were calculated for main effects and interactions. Results: Both active and control groups demonstrated improvements in executive function (EXAMINER composite: p < 0.001) and posttraumatic symptoms (NSI cognitive: p = 0.01) from baseline to 1 month. Active anodal tDCS was associated with greater improvements in working memory reaction time compared to control (p = 0.007). Reaction time improvement correlated significantly with the degree of connectivity change between the right DLPFC and the left anterior insula (p = 0.02). Conclusion: Anodal tDCS improved reaction time on an online working memory task in a mmTBI population, and decreased connectivity between executive network and salience network nodes. These findings generate important hypotheses for the mechanism of recovery from PPS after mild-moderate TBI.

Assessment of language impairment and function.

This chapter is written for the qualified neurologist or related professional working with persons who have had a stroke or other sudden brain injury. It is critical that the presence of aphasia is detected, no matter how mild the presentation, and to support that assertion, this chapter highlights the plight of persons with latent aphasia. At the individual level, the impact of aphasia is devastating, with overwhelming evidence that aphasia negatively impacts psychosocial outcomes. At the global level, sensitive detection and accurate diagnosis of aphasia are critical for accurate characterization and quantification of the global burden of aphasia. The word "LANGUAGE" is leveraged as an acronym to create a useful and memorable checklist to guide navigation of aphasia screening and assessment: it begins with the definition of language (L), followed by the definition and diagnostic criteria for aphasia (A). Then language abilities and characteristics to be considered in assessment are presented: naming (N); grammar and syntax (G); unintelligible words, jargon, and paraphasias (U); auditory comprehension and repetition (A); graphemic abilities-reading and writing (G); and everyday communication and discourse (E). Recommendations for improving procedural adherence are provided, and a list of potential brief assessment measures are introduced.

Repeated word production is inconsistent in both aphasia and apraxia of speech.

PURPOSE: There is persistent uncertainty about whether sound error consistency is a valid criterion for differentiating between apraxia of speech (AOS) and aphasia with phonemic paraphasia. The purpose of this study was to determine whether speakers with a profile of aphasia and AOS differ in error consistency from speakers with aphasia who do not have AOS. By accounting for differences in overall severity and using a sample size well over three times that of the largest study on the topic to date, our ambition was to resolve the existing controversy. METHOD: We analyzed speech samples from 171 speakers with aphasia and completed error consistency analysis for 137 of them. The experimental task was to repeat four multisyllabic words five times successively. Phonetic transcriptions were coded for four consistency indices (two at the sound-level and two at the word-level). We then used quantitative metrics to assign participants to four diagnostic groups (one aphasia plus AOS group, one aphasia only group, and two groups with intermediate speech profiles). Potential consistency differences were examined with ANCOVA, with error frequency as a continuous covariate. RESULTS: Error frequency was a strong predictor for three of the four consistency metrics. The magnitude of consistency for participants with AOS was either similar or lower compared to that of participants with aphasia only. Despite excellent transcription reliability and moderate to excellent coding reliability, three of the four consistency indices showed limited measurement reliability. DISCUSSION: People with AOS and people with aphasia often produce inconsistent variants of errors when they are asked to repeat challenging words several times sequentially. The finding that error consistency is similar or lower in aphasia with AOS than in aphasia without AOS is incompatible with recommendations that high error consistency be used as a diagnostic criterion for AOS. At the same time, group differences in the opposite direction are not sufficiently systematic to warrant use for differential diagnosis between aphasia with AOS and aphasia with phonemic paraphasia. Greater attention should be given to error propagation when estimating reliability of derived measurements.

Upper and Lower Limb Motor Function Correlates with Ipsilesional Corticospinal Tract and Red Nucleus Structural Integrity in Chronic Stroke: A Cross-Sectional, ROI-Based MRI Study.

BACKGROUND: Structural integrity of the ipsilesional corticospinal tract (CST) is important for upper limb motor recovery after stroke. However, additional neuromechanisms associated with motor function poststroke are less well understood, especially regarding the lower limb. OBJECTIVE: To investigate the neural basis of upper/lower limb motor deficits poststroke by correlating measures of motor function with diffusion tensor imaging-derived indices of white matter integrity (fractional anisotropy (FA), mean diffusivity (MD)) in primary and secondary motor tracts/structures. METHODS: Forty-three individuals with chronic stroke (time poststroke, 64.4 ± 58.8 months) underwent a comprehensive motor assessment and MRI scanning. Correlation and multiple regression analyses were performed to examine relationships between FA/MD in a priori motor tracts/structures and motor function. RESULTS: FA in the ipsilesional CST and red nucleus (RN) was positively correlated with motor function of both the affected upper and lower limb (r = 0.36-0.55, p ≤ 0.01), while only ipsilesional RN FA was associated with gait speed (r = 0.50). Ipsilesional CST FA explained 37.3% of the variance in grip strength (p < 0.001) and 31.5% of the variance in Arm Motricity Index (p = 0.004). Measures of MD were not predictors of motor performance. CONCLUSIONS: Microstructural integrity of the ipsilesional CST is associated with both upper and lower limb motor function poststroke, but appears less important for gait speed. Integrity of the ipsilesional RN was also associated with motor performance, suggesting increased contributions from secondary motor areas may play a role in supporting chronic motor function and could become a target for interventions.

Spectral Resting-State EEG (rsEEG) in Chronic Aphasia Is Reliable, Sensitive, and Correlates With Functional Behavior.

We investigated spectral resting-state EEG in persons with chronic stroke-induced aphasia to determine its reliability, sensitivity, and relationship to functional behaviors. Resting-state EEG has not yet been characterized in this population and was selected given the demonstrated potential of resting-state investigations using other neuroimaging techniques to guide clinical decision-making. Controls and persons with chronic stroke-induced aphasia completed two EEG recording sessions, separated by approximately 1 month, as well as behavioral assessments of language, sensorimotor, and cognitive domains. Power in the classic frequency bands (delta, theta, alpha, and beta) was examined via spectral analysis of resting-state EEG data. Results suggest that power in the theta, alpha, and beta bands is reliable for use as a repeated measure. Significantly greater theta and lower beta power was observed in persons with aphasia (PWAs) than controls. Finally, in PWAs theta power negatively correlated with performance on a discourse informativeness measure, while alpha and beta power positively correlated with performance on the same measure. This indicates that spectral rsEEG slowing observed in PWAs in the chronic stage is pathological and suggests a possible avenue for directly altering brain activation to improve behavioral function. Taken together, these results suggest that spectral resting-state EEG holds promise for sensitive measurement of functioning and change in persons with chronic aphasia. Future studies investigating the utility of these measures as biomarkers of frank or latent aphasic deficits and treatment response in chronic stroke-induced aphasia are warranted.

Main Concept, Sequencing, and Story Grammar Analyses of Cinderella Narratives in a Large Sample of Persons with Aphasia.

Recently, a multilevel analytic approach called Main Concept, Sequencing, and Story Grammar (MSSG) was presented along with preliminary normative information. MSSG analyses leverage the strong psychometrics and rich procedural knowledge of both main concept analysis and story grammar component coding, complementing it with easy-to-obtain sequencing information for a rich understanding of discourse informativeness and macrostructure. This study is the next critical step for demonstrating the clinical usefulness of MSSG's six variables (main concept composite, sequencing, main concept+sequencing, essential story grammar components, total episodic components, and episodic complexity) for persons with aphasia (PWAs). We present descriptive statistical information for MSSG variables for a large sample of PWAs and compare their performance to a large sample of persons not brain injured (PNBIs). We observed significant differences between PWAs and PNBIs for all MSSG variables. These differences occurred at the omnibus group level and for each aphasia subtype, even for PWAs with very mild impairment that is not detected with standardized aphasia assessment. Differences between PWAs and PNBIs were also practically significant, with medium to large effect sizes observed for nearly all aphasia subtypes and MSSG variables. This work deepens our understanding of discourse informativeness and macrostructure in PWAs and further develops an efficient tool for research and clinical use. Future research should investigate ways to expand MSSG analyses and to improve sensitivity and specificity.

Cerebral Perfusion Effects of Cognitive Training and Transcranial Direct Current Stimulation in Mild-Moderate TBI.

Background: Persistent post-traumatic symptoms (PPS) after traumatic brain injury (TBI) can lead to significant chronic functional impairment. Pseudocontinuous arterial spin labeling (pCASL) has been used in multiple studies to explore changes in cerebral blood flow (CBF) that may result in acute and chronic TBI, and is a promising neuroimaging modality for assessing response to therapies. Methods: Twenty-four subjects with chronic mild-moderate TBI (mmTBI) were enrolled in a pilot study of 10 days of computerized executive function training combined with active or sham anodal transcranial direct current stimulation (tDCS) for treatment of cognitive PPS. Behavioral surveys, neuropsychological testing, and magnetic resonance imaging (MRI) with pCASL sequences to assess global and regional CBF were obtained before and after the training protocol. Results: Robust improvements in depression, anxiety, complex attention, and executive function were seen in both active and sham groups between the baseline and post-treatment visits. Global CBF decreased over time, with differences in regional CBF noted in the right inferior frontal gyrus (IFG). Active stimulation was associated with static or increased CBF in the right IFG, whereas sham was associated with reduced CBF. Neuropsychological performance and behavioral symptoms were not associated with changes in CBF. Discussion: The current study suggests a complex picture between mmTBI, cerebral perfusion, and recovery. Changes in CBF may result from physiologic effect of the intervention, compensatory neural mechanisms, or confounding factors. Limitations include a small sample size and heterogenous injury sample, but these findings suggest promising directions for future studies of cognitive training paradigms in mmTBI.

Macrostructural Analyses of Cinderella Narratives in a Large Nonclinical Sample.

Purpose Macrostructural narrative analyses are important clinical measures, revealing age-related declines and disorder-related impairments in the accuracy, completeness, logical sequencing, and organization of content. The current study aims to provide preliminary data on typical aging and psychometric evidence supporting multilevel Main Concept, Sequencing, and Story Grammar (MSSG) analyses that capture these aspects of narratives. Method Transcripts of Cinderella narratives for 92 healthy control participants stratified across four age brackets from the online database AphasiaBank were coded by Richardson and Dalton (2016) for main concept (MC) analysis. In the current study, MSSG analyses were completed for (a) logical sequencing, independently and in combination with MC accuracy and completeness (MC + sequencing), and (b) story grammar organization (i.e., inclusion of episodic components and complexity of episodes). Interrater agreement (99%-100%) revealed highly reliable scoring. Results Descriptive statistics for the typically aging sample are presented for sequencing, MC + sequencing, total episodic components, and episodic complexity. Scores for participants over 60 years of age were lower (poorer) than scores for those 20-59 years of age, supporting the construct validity of score use for identifying age-related declines in performance. Conclusions This study's novel MSSG analyses of narrative production efficiently assess the logical sequencing and story grammar organization of content in healthy controls. Preliminary reliability and validity evidence support the use of all scores to measure age-related changes in narrative macrostructure. Data from this typically aging sample provide a foundation for future research and clinical assessment aimed at quantifying narrative deficits in adults with communication disorders. Supplemental Material https://doi.org/10.23641/asha.12683495.

Main concepts for two picture description tasks: An addition to.

BACKGROUND: Proposition analysis of the discourse of persons with aphasia has a long history, yielding important advancements in our understanding of communication impairments in this population. Recently, discourse measures have been considered primary outcome measures, and multiple calls have been made for improved psychometric properties of discourse measures. AIMS: To advance the use of discourse analysis in persons with aphasia by providing Main Concept Analysis checklists and descriptive statistics for healthy control performance on the analysis for the Cat in the Tree and Refused Umbrella narrative tasks utilized in the AphasiaBank database protocol. METHODS & PROCEDURES: Ninety-two control transcripts, stratified into four age groups (20-39 years; 40-59; 60-79; 80+), were downloaded from the AphasiaBank database. Relevant concepts were identified, and those spoken by at least one-third of the control sample were considered to be a main concept. A multi-level coding system was used to determine the accuracy and completeness of the main concepts produced by control speakers. OUTCOMES & RESULTS: Main concept checklists for two discourse tasks are provided. Descriptive statistics are reported and examined to assist readers with evaluation of the normative data. CONCLUSIONS: These checklists provide clinicians and researchers with a tool to reliably assess the discourse of persons with aphasia. They also help address the gap in available psychometric data with which to compare persons with aphasia to healthy controls.

Developing, Implementing, and Improving Assessment and Treatment Fidelity in Clinical Aphasia Research.

Purpose The purpose of this study was to describe the development and implementation of a fidelity program for an ongoing, multifacility, aphasia intervention study and to explain how initial fidelity measures are being used to improve study integrity. Method A Clinical Core team developed and incorporated a fidelity plan in this study. The aims of the Clinical Core team were to (a) supervise data collection and data management at each clinical site, (b) optimize and monitor assessment fidelity, and (c) optimize and monitor treatment fidelity. Preliminary data are being used to guide ongoing efforts to preserve and improve the fidelity of this intervention study. Results Preliminary results show that specific recruitment strategies help to improve appropriate referrals and that accommodations to participants and their families help to maintain excellent retention. A streamlined and centralized training program assures the reliability of assessors and raters for the study's assessment and treatment protocols. Ongoing monitoring of both assessment and treatment tasks helps to maintain study integrity. Less-than-optimal interrater reliability data for the raters of some of the discourse measures guided the Clinical Core team to address the training and coding inconsistencies in a timely manner. Conclusions The creation of a Clinical Core team is instrumental in developing and implementing a fidelity plan for improved assessment and treatment fidelity. Intentional planning and assignment of study staff to implement and monitor ongoing fidelity measures assures that clinical data are reliable and valid. Ongoing review of the plan shows areas of strengths and weaknesses for continuing adjustments and improvement of study fidelity.

Moving Toward Non-transcription based Discourse Analysis in Stable and Progressive Aphasia.

Measurement of communication ability at the discourse level holds promise for predicting how well persons with stable (e.g., stroke-induced), or progressive aphasia navigate everyday communicative interactions. However, barriers to the clinical utilization of discourse measures have persisted. Recent advancements in the standardization of elicitation protocols and the existence of large databases for development of normative references have begun to address some of these barriers. Still, time remains a consistently reported barrier by clinicians. Non-transcription based discourse measurement would reduce the time required for discourse analysis, making clinical utilization a reality. The purpose of this article is to present evidence regarding discourse measures (main concept analysis, core lexicon, and derived efficiency scores) that are well suited to non-transcription based analysis. Combined with previous research, our results suggest that these measures are sensitive to changes following stroke or neurodegenerative disease. Given the evidence, further research specifically assessing the reliability of these measures in clinical implementation is warranted.

A Compendium of Core Lexicon Checklists.

Core Lexicon (CoreLex) is a relatively new approach assessing lexical use in discourse. CoreLex examines the specific lexical items used to tell a story, or how typical lexical items are compared with a normative sample. This method has great potential for clinical utilization because CoreLex measures are fast, easy to administer, and correlate with microlinguistic and macrolinguistic discourse measures. The purpose of this article is to provide clinicians with a centralized resource for currently available CoreLex checklists, including information regarding development, norms, and guidelines for use.

Can Script Training Improve Narrative and Conversation in Aphasia across Etiology?

Script training is an effective treatment of stable (e.g., stroke-induced) and progressive aphasia of varying severities and subtypes. The theoretical underpinnings of script training are discussed and include fluency-inducing conditions, speech shadowing, principles of neuroplasticity, and automatization. Script training outcomes are reviewed, with a focus on discourse in persons with stable aphasia (PWSAs) and in persons with primary progressive aphasia (PWPPAs). PWSAs and PWPPAs are able to acquire and maintain short scripted monologues or conversational dialogues, with some evidence of generalization to untrained topics and settings. Advances in both technology and access have enriched script training protocols, so they now range from no-tech written script approaches to high-tech audiovisual support and avatars. Advances in audio and/or visual support promote large amounts of practice of less errorful whole-message language processing during a fluent language inducing condition. With enough practice, users decrease reliance on supports and independently produce scripted content. Script training can be delivered in a variety of settings (individual, group, telepractice), lends itself well to homework programs, and is in accordance with the principles of neuroplasticity for neurorehabilitation. Incorporating script training into therapy programming is advantageous throughout aphasia recovery following brain injuries such as stroke. It is also beneficial for persons with progressive disease for prophylaxis, remediation, and compensation. Recommendations for implementing script training in clinical practice and future research directions are presented.

A Large-Scale Comparison of Main Concept Production Between Persons With Aphasia and Persons Without Brain Injury.

Purpose The purposes of this study are to provide clinicians and researchers with introductory psychometric data for the main concept analysis (MCA), a measure of discourse informativeness, and specifically, to provide descriptive and comparative statistical information about the performance of a large sample of persons not brain injured (PNBIs) and persons with aphasia (PWAs) on AphasiaBank discourse tasks. Method Transcripts of 5 semi-spontaneous discourse tasks were retrieved from the AphasiaBank database and scored according to detailed checklists and scoring procedures. Transcripts from 145 PNBIs and 238 PWAs were scored; descriptive statistics, median tests, and effect sizes are reported. Results PWAs demonstrated overall lower informativeness scores and more frequent production of statements that were inaccurate and/or incomplete. Differences between PNBIs and PWAs were observed for all main concept measures and stories. Comparisons of PNBIs and aphasia subtypes revealed significant differences for all groups, although the pattern of differences and strength of effect sizes varied by group and discourse task. Conclusions These results may improve the investigative and clinical utility of the MCA by providing descriptive and comparative information for PNBIs and PWAs for standardized discourse tasks that can be reliably scored. The results indicate that the MCA is sensitive to differences in discourse as a result of aphasia. Supplemental Material https://doi.org/10.23641/asha.7485647.

Describing Phonological Paraphasias in Three Variants of Primary Progressive Aphasia.

Purpose: The purpose of this study was to describe the linguistic environment of phonological paraphasias in 3 variants of primary progressive aphasia (semantic, logopenic, and nonfluent) and to describe the profiles of paraphasia production for each of these variants. Method: Discourse samples of 26 individuals diagnosed with primary progressive aphasia were investigated for phonological paraphasias using the criteria established for the Philadelphia Naming Test (Moss Rehabilitation Research Institute, 2013). Phonological paraphasias were coded for paraphasia type, part of speech of the target word, target word frequency, type of segment in error, word position of consonant errors, type of error, and degree of change in consonant errors. Results: Eighteen individuals across the 3 variants produced phonological paraphasias. Most paraphasias were nonword, followed by formal, and then mixed, with errors primarily occurring on nouns and verbs, with relatively few on function words. Most errors were substitutions, followed by addition and deletion errors, and few sequencing errors. Errors were evenly distributed across vowels, consonant singletons, and clusters, with more errors occurring in initial and medial positions of words than in the final position of words. Most consonant errors consisted of only a single-feature change, with few 2- or 3-feature changes. Importantly, paraphasia productions by variant differed from these aggregate results, with unique production patterns for each variant. Conclusions: These results suggest that a system where paraphasias are coded as present versus absent may be insufficient to adequately distinguish between the 3 subtypes of PPA. The 3 variants demonstrate patterns that may be used to improve phenotyping and diagnostic sensitivity. These results should be integrated with recent findings on phonological processing and speech rate. Future research should attempt to replicate these results in a larger sample of participants with longer speech samples and varied elicitation tasks. Supplemental Materials: https://doi.org/10.23641/asha.5558107.

The Relationship Between Confrontation Naming and Story Gist Production in Aphasia.

Purpose: The purpose of this study was to examine the relationship between picture naming performance and the ability to communicate the gist, or essential elements, of a story. We also sought to determine if this relationship varied according to Western Aphasia Battery-Revised (WAB-R; Kertesz, 2007) aphasia subtype. Method: Demographic information, test scores, and transcripts of 258 individuals with aphasia completing 3 narrative tasks were retrieved from the AphasiaBank database. Narratives were subjected to a main concept analysis to determine gist production. A correlation analysis was used to investigate the relationship between naming scores and main concept production for the whole group of persons with aphasia and for WAB-R subtypes separately. Results: We found strong correlations between naming test scores and narrative gist production for the large sample of persons with aphasia. However, the strength of the correlations varied by WAB-R subtype. Conclusions: Picture naming may accurately predict gist production for individuals with Broca's and Wernicke's aphasia, but not for other WAB-R subtypes. Given the current reprioritization of outcome measurement, picture naming may not be an appropriate surrogate measure for functional communication for all persons with aphasia. Supplemental Materials: https://doi.org/10.23641/asha.5851848.

Rigor and reproducibility in research with transcranial electrical stimulation: An NIMH-sponsored workshop.

BACKGROUND: Neuropsychiatric disorders are a leading source of disability and require novel treatments that target mechanisms of disease. As such disorders are thought to result from aberrant neuronal circuit activity, neuromodulation approaches are of increasing interest given their potential for manipulating circuits directly. Low intensity transcranial electrical stimulation (tES) with direct currents (transcranial direct current stimulation, tDCS) or alternating currents (transcranial alternating current stimulation, tACS) represent novel, safe, well-tolerated, and relatively inexpensive putative treatment modalities. OBJECTIVE: This report seeks to promote the science, technology and effective clinical applications of these modalities, identify research challenges, and suggest approaches for addressing these needs in order to achieve rigorous, reproducible findings that can advance clinical treatment. METHODS: The National Institute of Mental Health (NIMH) convened a workshop in September 2016 that brought together experts in basic and human neuroscience, electrical stimulation biophysics and devices, and clinical trial methods to examine the physiological mechanisms underlying tDCS/tACS, technologies and technical strategies for optimizing stimulation protocols, and the state of the science with respect to therapeutic applications and trial designs. RESULTS: Advances in understanding mechanisms, methodological and technological improvements (e.g., electronics, computational models to facilitate proper dosing), and improved clinical trial designs are poised to advance rigorous, reproducible therapeutic applications of these techniques. A number of challenges were identified and meeting participants made recommendations made to address them. CONCLUSIONS: These recommendations align with requirements in NIMH funding opportunity announcements to, among other needs, define dosimetry, demonstrate dose/response relationships, implement rigorous blinded trial designs, employ computational modeling, and demonstrate target engagement when testing stimulation-based interventions for the treatment of mental disorders.

Cortical disconnection of the ipsilesional primary motor cortex is associated with gait speed and upper extremity motor impairment in chronic left hemispheric stroke.

Advances in neuroimaging have enabled the mapping of white matter connections across the entire brain, allowing for a more thorough examination of the extent of white matter disconnection after stroke. To assess how cortical disconnection contributes to motor impairments, we examined the relationship between structural brain connectivity and upper and lower extremity motor function in individuals with chronic stroke. Forty-three participants [mean age: 59.7 (±11.2) years; time poststroke: 64.4 (±58.8) months] underwent clinical motor assessments and MRI scanning. Nonparametric correlation analyses were performed to examine the relationship between structural connectivity amid a subsection of the motor network and upper/lower extremity motor function. Standard multiple linear regression analyses were performed to examine the relationship between cortical necrosis and disconnection of three main cortical areas of motor control [primary motor cortex (M1), premotor cortex (PMC), and supplementary motor area (SMA)] and motor function. Anatomical connectivity between ipsilesional M1/SMA and the (1) cerebral peduncle, (2) thalamus, and (3) red nucleus were significantly correlated with upper and lower extremity motor performance (P ≤ 0.003). M1-M1 interhemispheric connectivity was also significantly correlated with gross manual dexterity of the affected upper extremity (P = 0.001). Regression models with M1 lesion load and M1 disconnection (adjusted for time poststroke) explained a significant amount of variance in upper extremity motor performance (R2  = 0.36-0.46) and gait speed (R2  = 0.46), with M1 disconnection an independent predictor of motor performance. Cortical disconnection, especially of ipsilesional M1, could significantly contribute to variability seen in locomotor and upper extremity motor function and recovery in chronic stroke. Hum Brain Mapp 39:120-132, 2018. © 2017 Wiley Periodicals, Inc.