Mapping spoken language and cognitive deficits in post-stroke aphasia

Aphasia is an acquired disorder caused by damage, most commonly due to stroke, to brain regions involved in speech and language. While language impairment is the defining symptom of aphasia, the co-occurrence of non-language cognitive deficits and their importance in predicting rehabilitation and recovery outcomes is well documented. However, people with aphasia (PWA) are rarely tested on higher-order cognitive functions, making it difficult for studies to associate these functions with a consistent lesion correlate. Broca's area is a particular brain region of interest that has long been implicated in speech and language production. Contrary to classic models of speech and language, cumulative evidence shows that Broca's area and surrounding regions in the left inferior frontal cortex (LIFC) are involved in, but not specific to, speech production. In this study we aimed to explore the brain-behaviour relationships between tests of cognitive skill and language abilities in thirty-six adults with long-term speech production deficits caused by post-stroke aphasia. Our findings suggest that non-linguistic cognitive functions, namely executive functions and verbal working memory, explain more of the behavioural variance in PWA than classical language models imply. Additionally, lesions to the LIFC, including Broca's area, were associated with non-linguistic executive (dys)function, suggesting that lesions to this area are associated with non-language-specific higher-order cognitive deficits in aphasia. Whether executive (dys)function - and its neural correlate in Broca's area - contributes directly to PWA's language production deficits or simply co-occurs with it, adding to communication difficulties, remains unclear. These findings support contemporary models of speech production that place language processing within the context of domain-general perception, action and conceptual knowledge. An understanding of the covariance between language and non-language deficits and their underlying neural correlates will inform better targeted aphasia treatment and outcomes

Mapping spoken language and cognitive deficits in post-stroke aphasia

Aphasia is an acquired disorder caused by damage, most commonly due to stroke, to brain regions involved in speech and language. While language impairment is the defining symptom of aphasia, the co-occurrence of non-language cognitive deficits and their importance in predicting rehabilitation and recovery outcomes is well documented. However, people with aphasia (PWA) are rarely tested on higher-order cognitive functions, making it difficult for studies to associate these functions with a consistent lesion correlate. Broca's area is a particular brain region of interest that has long been implicated in speech and language production. Contrary to classic models of speech and language, cumulative evidence shows that Broca's area and surrounding regions in the left inferior frontal cortex (LIFC) are involved in, but not specific to, speech production. In this study we aimed to explore the brain-behaviour relationships between tests of cognitive skill and language abilities in thirty-six adults with long-term speech production deficits caused by post-stroke aphasia. Our findings suggest that non-linguistic cognitive functions, namely executive functions and verbal working memory, explain more of the behavioural variance in PWA than classical language models imply. Additionally, lesions to the LIFC, including Broca's area, were associated with non-linguistic executive (dys)function, suggesting that lesions to this area are associated with non-language-specific higher-order cognitive deficits in aphasia. Whether executive (dys)function – and its neural correlate in Broca's area – contributes directly to PWA's language production deficits or simply co-occurs with it, adding to communication difficulties, remains unclear. These findings support contemporary models of speech production that place language processing within the context of domain-general perception, action and conceptual knowledge. An understanding of the covariance between language and non-language deficits and their underlying neural correlates will inform better targeted aphasia treatment and outcomes

Predicting online behavioural responses to transcranial direct current stimulation in stroke patients with anomia

Anomia, or difficulty naming common objects, is the most common, acquired impairment of language. Effective therapeutic interventions for anomia typically involve massed practice at high doses. This requires significant investment from patients and therapists. Aphasia researchers have increasingly looked to neurostimulation to accelerate these treatment effects, but the evidence behind this intervention is sparse and inconsistent. Here, we hypothesised that group-level neurostimulation effects might belie a more systematic structure at the individual level. We sought to test the hypothesis by attempting to predict the immediate (online), individual-level behavioural effects of anodal and sham neurostimulation in 36 chronic patients with anomia, performing naming and size judgement tasks. Using clinical, (pre-stimulation) behavioural and MRI data, as well as Partial Least Squares regression, we attempted to predict neurostimulation effects on accuracies and reaction times of both tasks. Model performance was assessed via cross-validation. Predictive performances were compared to that of a null model, which predicted the mean neurostimulation effects for all patients. Models derived from pre-stimulation data consistently outperformed the null model when predicting neurostimulation effects on both tasks’ performance. Notably, we could predict behavioural declines just as well as improvements. In conclusion, inter-patient variation in online responses to neurostimulation is, to some extent, systematic and predictable. Since declines in performance were just as predictable as improvements, the behavioural effects of neurostimulation in patients with anomia are unlikely to be driven by placebo effects. However, the online effect of the intervention appears to be as likely to interfere with task performance as to improve it

Predicting online behavioural responses to transcranial direct current stimulation in stroke patients with anomia

BACKGROUND: Anomia, or difficulty naming common objects, is the most common, acquired impairment of language. Effective therapeutic interventions for anomia typically involve massed practice at high doses, requiring significant investment from patients and therapists. Aphasia researchers have increasingly looked to neurostimulation to accelerate these treatment effects, but the evidence behind this intervention is sparse and inconsistent. AIM: Here, we hypothesised that group-level neurostimulation effects might belie more systematic structure at the individual level. We sought to test the hypothesis by attempting to predict the immediate (online), individual-level behavioural effect of neurostimulation in patients with anomia. METHODS: 36 stroke patients, each with anomia at least 6 months post-onset, were asked to perform naming and judgement tasks both with concurrent neurostimulation and with sham stimulation. Using clinical, (pre-stimulation) behavioural and MRI data, and Partial Least Squares regression, we attempted to predict the effect of neurostimulation on accuracies and reaction times in both tasks. Model performance was assessed via cross-validation, and performances compared to that of a null model, which predicted the mean neurostimulation effects for all patients. RESULTS: Models derived from pre-stimulation data consistently out-performed the null model when predicting neurostimulation effects on accuracies and reaction times in both judgement and naming. Notably, we could predict declines in performance just as well as improvements. CONCLUSIONS: Inter-patient variation in online responses to neurostimulation is to some extent systematic and predictable. That declines in performance were just as predictable as improvements, implies that the effect of neurostimulation on performance in patients with anomia is unlikely to be a placebo. However, the online effect of the intervention appears to be just as likely to interfere with task performance, as it is to improve performance

Motor training reduces surround inhibition in the motor cortex

OBJECTIVE: Surround inhibition (SI) is thought to facilitate focal contraction of a hand muscle by keeping nearby muscles silent. Unexpectedly, SI is reduced in skilled pianists. We tested whether repeated practice of focal contraction in non-pianists could reduce SI. METHODS: Motor-evoked potentials were elicited by transcranial magnetic stimulation in the relaxed abductor digiti minimi randomly at the onset and 5s after offset of a 2s focal contraction (10% maximum) of the first dorsal interosseous (FDI). Over 5 blocks of 40 trials participants obtained points for increasing contraction speed and stability in FDI. In a final block, the interval between contractions was varied randomly to increase attention to the task. RESULTS: Over the first 5 blocks, SI declined as performance (points scored) improved. In the final "attention" block SI increased towards baseline without affecting performance. CONCLUSIONS: Although SI may be useful during the early stages of learning, skilled focal finger movement does not require SI to prevent activity in non-involved muscles. This could be due to better targeting of the excitatory command to move. Results from the final block suggest that increased attention can re-engage SI when task parameters change. SIGNIFICANCE: SI is not necessary for successful focal contraction, but may contribute during learning and during attention to task

Understanding the burden of mental and physical health disorders on families: findings from the Saudi National Mental Health Survey

Objective To assess prevalence and correlation of factors of family burden associated with mental and physical disorders in the general population of Saudi Arabia.Setting and participants A secondary analysis of data from the Saudi National Mental Health Survey (SNMHS).Outcome measures Mental and physical health disorders of first-degree relatives and objective (time, financial) and subjective (distress, embarrassment) family burden.Results We found significant caregiver burden for family members with mental health disorders. Around one-third of the sample was providing care for a family member with a health issue. Within this group, 40% had a mental health diagnosis. 73% of the study population reported experiencing some form of burden as a result of the care they are obligated to provide for their family members. We found the highest burden on male caregivers, in providing care for family members with serious memory disorders, mental retardation, schizophrenia or psychosis, followed by, alcohol and drug disorders, anxiety, depression or manic depression.Conclusion Our findings for family burden were statistically significant, indicating potential negative impact on caregiver coping ability with the demands of caring for family members with health issues. A comprehensive review of national mental health policies is required to integrate aspects of community mental health promotion, scale-up prevention, screening interventions and social support to protect against the difficulties of mental illness and reduce the burden on caregivers, the family, society, health system and the economy