Neural Regions Underlying Object and Action Naming: Complementary Evidence from Acute Stroke and Primary Progressive Aphasia

Background: Naming impairment is commonly noted in individuals with aphasia. However, object naming receives more attention than action naming. Furthermore, most studies include participants with aphasia due to only one aetiology, commonly stroke. We developed a new assessment, the Hopkins Action Naming Assessment (HANA), to evaluate action naming impairments. Methods \u3e& Procedures: Participants (N = 138 PPA, N = 37 acute stroke) completed the BNT and HANA. Behavioural performance was compared. A subset of participants (N = 31 PPA, N = 37 acute stroke) provided neuroimaging data. The whole brain was automatically segmented into regions of interest (ROIs). For participants with PPA, the image variables were the ROI volumes, normalised by brain volume. For participants with acute stroke, the image variables were the percentage of each ROI that was lesioned. The relationship between ROIs likely to be involved in naming performance was modelled with LASSO regression. Outcomes & Results: Behavioural results showed a double dissociation in performance: in each group, some participants displayed intact performance relative to healthy controls on actions but not objects and/or significantly better performance on actions than objects, while others showed the opposite pattern. These results support the need to assess both objects and actions when evaluating naming deficits. Neuroimaging results identified different regions associated with object vs. action naming, implicating overlapping but distinct networks of regions. Furthermore, results differed for participants with PPA vs. acute stroke, indicating that critical information may be missed when only one aetiology is considered. Conclusions: Overall, the study provides a more comprehensive picture of the neural bases of naming, underscoring the importance of assessing both objects and actions and considering different aetiologies of damage. It demonstrates the HANA\u27s utility

Cerebellar tDCS: A Novel Approach to Augment Language Treatment Post-stroke

People with post-stroke aphasia may have some degree of chronic deficit for which current rehabilitative treatments are variably effective. Accumulating evidence suggests that transcranial direct current stimulation (tDCS) may be useful for enhancing the effects of behavioral aphasia treatment. However, it remains unclear which brain regions should be stimulated to optimize effects on language recovery. Here, we report on the therapeutic potential of right cerebellar tDCS in augmenting language recovery in SMY, who sustained bilateral MCA infarct resulting in aphasia and anarthria. We investigated the effects of 15 sessions of anodal cerebellar tDCS coupled with spelling therapy using a randomized, double-blind, sham controlled within-subject crossover trial. We also investigated changes in functional connectivity using resting state functional magnetic resonance imaging before and 2 months post-treatment. Both anodal and sham treatments resulted in improved spelling to dictation for trained and untrained words immediately after and 2 months post-treatment. However, there was greater improvement with tDCS than with sham, especially for untrained words. Further, generalization to written picture naming was only noted during tDCS but not with sham. The resting state functional connectivity data indicate that improvement in spelling was accompanied by an increase in cerebro-cerebellar network connectivity. These results highlight the therapeutic potential of right cerebellar tDCS to augment spelling therapy in an individual with large bilateral chronic strokes

Developing, monitoring, and reporting of fidelity in aphasia trials: Core recommendations from the collaboration of aphasia trialists (CATs) trials for aphasia panel

Background: Developing, monitoring, and reporting of fidelity are essential and integral components to the design of randomised controlled trials (RCTs) in stroke and aphasia. Treatment fidelity refers to the degree to which an intervention is delivered as intended and is directly related to the quality of the evidence generated by RCTs. Clear documentation of treatment fidelity in trials assists in the evaluation of the clinical implications of potential benefits attributed to the intervention. Consideration of the implementation requirements of a research-based intervention as intended in a clinical context is necessary to achieve similar outcomes for a clinical population. Despite this, treatment fidelity is rarely reported in RCTs of aphasia intervention. Aim: To describe fidelity strategies and develop core recommendations for developing, monitoring, and reporting of fidelity in aphasia intervention RCTs. Scope: Relevant conceptual frameworks were considered. The Behaviour Change Consortium comprehensive framework of fidelity was adopted. It includes five areas: study design, training providers, delivery of treatment, treatment receipt, and treatment enactment. We explored fidelity in RCTs with a range of complex aphasia interventions (e.g., ASK, Big CACTUS, COMPARE, FCET2EC, POLAR, SUPERB, and VERSE) and described how different trial design factors (e.g., phase of trial, explanatory vs. pragmatic, number and location of sites, and number and type of treatment providers) influenced the fidelity strategies chosen. Strategies were mapped onto the five areas of the fidelity framework with a detailed exploration of how fidelity criteria were developed, measured, and monitored throughout each trial. This information was synthesised into a set of core recommendations to guide aphasia researchers towards the adequate measurement, capture, and reporting of fidelity within future aphasia intervention studies. Conclusions/Recommendations: Treatment fidelity should be a core consideration in planning an intervention trial, a concept that goes beyond treatment adherence alone. A range of strategies should be selected depending on the phase and design of the trial being undertaken and appropriate investment of time and costs should be considered

Online speech synthesis using a chronically implanted brain–computer interface in an individual with ALS

Brain–computer interfaces (BCIs) that reconstruct and synthesize speech using brain activity recorded with intracranial electrodes may pave the way toward novel communication interfaces for people who have lost their ability to speak, or who are at high risk of losing this ability, due to neurological disorders. Here, we report online synthesis of intelligible words using a chronically implanted brain-computer interface (BCI) in a man with impaired articulation due to ALS, participating in a clinical trial (ClinicalTrials.gov, NCT03567213) exploring different strategies for BCI communication. The 3-stage approach reported here relies on recurrent neural networks to identify, decode and synthesize speech from electrocorticographic (ECoG) signals acquired across motor, premotor and somatosensory cortices. We demonstrate a reliable BCI that synthesizes commands freely chosen and spoken by the participant from a vocabulary of 6 keywords previously used for decoding commands to control a communication board. Evaluation of the intelligibility of the synthesized speech indicates that 80% of the words can be correctly recognized by human listeners. Our results show that a speech-impaired individual with ALS can use a chronically implanted BCI to reliably produce synthesized words while preserving the participant’s voice profile, and provide further evidence for the stability of ECoG for speech-based BCIs

Stable Decoding from a Speech BCI Enables Control for an Individual with ALS without Recalibration for 3 Months

Brain-computer interfaces (BCIs) can be used to control assistive devices by patients with neurological disorders like amyotrophic lateral sclerosis (ALS) that limit speech and movement. For assistive control, it is desirable for BCI systems to be accurate and reliable, preferably with minimal setup time. In this study, a participant with severe dysarthria due to ALS operates computer applications with six intuitive speech commands via a chronic electrocorticographic (ECoG) implant over the ventral sensorimotor cortex. Speech commands are accurately detected and decoded (median accuracy: 90.59%) throughout a 3-month study period without model retraining or recalibration. Use of the BCI does not require exogenous timing cues, enabling the participant to issue self-paced commands at will. These results demonstrate that a chronically implanted ECoG-based speech BCI can reliably control assistive devices over long time periods with only initial model training and calibration, supporting the feasibility of unassisted home use

The Persistence of the Self over Time in Mild Cognitive Impairment and Alzheimer's Disease

Diachronic unity is the belief that, despite changes, we are the same person across the lifespan. We propose that diachronic unity is supported by the experience of remembering the self over time during episodic recall (i.e., phenomenological continuity). However, we also predict that diachronic unity is also possible when episodic memory is impaired, as long as the ability to construct life narratives from semantic memory (i.e., semantic continuity) is intact. To examine this prediction, we investigated diachronic unity in Alzheimer's Disease (AD) and amnestic mild cognitive impairment (aMCI), two conditions characterised by disrupted phenomenological continuity. If semantic continuity is also altered in these conditions, there should be an associated deterioration in diachronic unity. Participants with AD, aMCI, and healthy controls (HC) completed a self-persistence interview measuring diachronic unity (beliefs about self-persistence, explanations for stability/change). Semantic continuity was assessed with a life-story interview measuring autobiographical reasoning (self-event connections), and coherence (temporal/thematic/causal) of narratives. Our results highlight a complex relationship between semantic continuity and diachronic unity and revealed a divergence between two aspects of diachronic unity: AD/aMCI groups did not differ from HC in continuity beliefs, but AD explanations for self-persistence were less sophisticated. Semantic continuity was most impaired in AD: their narratives had fewer self-event connections (vs. HCs) and lower temporal/thematic coherence (vs. HC/aMCI), while both AD/aMCI groups had lower causal coherence. Paradoxically AD participants who scored higher on measures of beliefs in the persistence of the core self, provided less sophisticated explanations for their self-persistence and were less able to explore persistence in their life narratives. These findings support the importance of semantic continuity to diachronic unity, but suggest a more nuanced and multifaceted relationship than originally proposed in our model. In AD, diminished life narratives that retain features of cultural life scripts are sufficient for strong subjective beliefs of self-persistence, but not for sophisticated explanations about persistence. Better semantic continuity, with the ability to weave high-quality life narratives, may scaffold the capacity to understand and explain one's diachronic unity, but this produces less surety about self-persistence

Where are aphasia theory and management “headed”? [version 1; referees: 2 approved]

The sequelae of post-stroke aphasia are considerable, necessitating an understanding of the functional neuroanatomy of language, cognitive processes underlying various language tasks, and the mechanisms of recovery after stroke. This knowledge is vital in providing optimal care of individuals with aphasia and counseling to their families and caregivers. The standard of care in the rehabilitation of aphasia dictates that treatment be evidence-based and person-centered. Promising techniques, such as cortical stimulation as an adjunct to behavioral therapy, are just beginning to be explored. These topics are discussed in this review

Differentiating between subtypes of primary progressive aphasia and mild cognitive impairment on a modified version of the Frontal Behavioral Inventory.

Behavioral assessment has been investigated in frontotemporal lobar degeneration and Alzheimer's disease, but has not been explored extensively in subtypes of primary progressive aphasia (PPA). We explored the ability of a modified version of the Frontal Behavioral Inventory (FBI-mod) to discriminate between patients with distinct subtypes of PPA and patients with mild cognitive impairment (MCI). We hypothesized that individuals with nonfluent agrammatic PPA (nfaPPA) would have higher negative behavior scores than other groups and that individuals with semantic variant PPA (svPPA) would have higher disinhibition scores than other groups. Family members and/or caregivers of 120 individuals with PPA and MCI (mean age 69.54+8.75 years; 65 (54%) female; education 16.06±2.68 years; disease duration 46.47±34.26 months) completed the FBI-mod [logopenic PPA (lvPPA) n = 40. nfaPPA n = 29, svPPA n = 27, MCI n = 24]. The groups were not significantly different in age, gender, education, or disease duration. There were no significant differences between the groups for negative behaviors (p = 0.72) and disinhibition scores (p = 0.14). When comparing negative and disinhibition scores (in percent), negative scores were significantly higher in all groups (p < 0.001). When comparing subtest items, there was a pairwise difference between lvPPA and svPPA for restlessness (lvPPA < svPPA, p = 0.02, after adjusting for multiple between-group comparisons). There was a significant difference in the proportion of severe neglect between the groups with lvPPA having a lower proportion than the other two variants (p = 0.05), and there was a significant difference in the proportion of severe poor judgment between the groups with lvPPA also having a lower proportion than nfaPPA (p = 0.04). This study reveals the greater negative behavioral disturbance than disinhibition in the PPA and MCI groups of similar age and duration since onset and identifies different profiles for some specific behaviors for the PPA groups. These findings may have clinical and practical implications

The association of insular stroke with lesion volume

The insula has been implicated in many sequelae of stroke. It is the area most commonly infarcted in people with post-stroke arrhythmias, loss of thermal sensation, hospital acquired pneumonia, and apraxia of speech. We hypothesized that some of these results reflect the fact that: (1) ischemic strokes that involve the insula are larger than strokes that exclude the insula (and therefore are associated with more common and persistent deficits); and (2) insular involvement is a marker of middle cerebral artery (MCA) occlusion. We analyzed MRI scans of 861 patients with acute ischemic hemispheric strokes unselected for functional deficits, and compared infarcts involving the insula to infarcts not involving the insula using t-tests for continuous variables and chi square tests for dichotomous variables. Mean infarct volume was larger for infarcts including the insula (n = 232) versus excluding the insula (n = 629): 65.8 ± 78.8 versus 10.2 ± 15.9 cm3 (p < 0.00001). Even when we removed lacunar infarcts, mean volume of non-lacunar infarcts that included insula (n = 775) were larger than non-lacunar infarcts (n = 227) that excluded insula: 67.0 cm3 ± 79.2 versus 11.5 cm3 ± 16.7 (p < 0.00001). Of infarcts in the 90th percentile for volume, 87% included the insula (χ2 = 181.8; p < 0.00001). Furthermore, 79.0% infarcts due to MCA occlusion included the insula; 78.5% of infarcts without MCA occlusion excluded the insula (χ2 = 93.1; p < 0.0001). The association between insular damage and acute or chronic sequelae likely often reflects the fact that insular infarct is a marker of large infarcts caused by occlusion of the MCA more than a specific role of the insula in a range of functions. Particularly in acute stroke, some deficits may also be due to ischemia of the MCA or ICA territory caused by large vessel occlusion