Task-related factors in oral motor control: speech and oral diadochokinesis in dysarthria and apraxia of speech

This study was focused on the potential influence of task-related factors on oral motor performance in patients with speech disorders. Sentence production was compared with a nonspeech oral motor task, i.e., oral diadochokinesis. Perceptual and acoustic measures of speech impairment were used as dependent variables. Between-task comparisons were made for subsamples of a population of 140 patients with different motor speech syndromes, including apraxia of speech and cerebellar dysarthria. In a further analysis subgroups were matched for speaking rate. Overall, dysdiadochokinesis was correlated with the degree of speech impairment, but there was a strong interaction between task type and motor speech syndrome. In particular, cerebellar pathology affected DDK to a relatively greater extent than sentence production, while apraxic pathology spared the ability of repeating syllables at maximum speed.     

The topography of aggressive behavior of an attacking rat is determined by the behavior of the victim

Untreated rats were observed to either bite or box with Pentobarbital-treated opponents in a shockelicited aggression situation. Specific behaviors such as ataxia movements and submissive postures immediately preceded biting attacks, but rarely boxing whereas behaviors such as moving around the chamber and upright threat postures immediately preceded boxing attacks, but rarely biting. These data suggest that the topography of aggressive behavior of an attacking rat is determined by the behavior of the victim.     

Depressive symptoms in Friedreich ataxiaSíntomas depresivos en la ataxia de Friedreich

Background/Objective: Almost no attention has been paid to depression in Friedreich ataxia (FRDA), a highly disabling cerebellar degenerative disease. Our aim was to study the presence and the profile of depressive symptoms in FRDA and their relationship with demographic-disease variables and cognitive processing speed. Method: The study groups consisted of 57 patients with a diagnosis of FRDA. The Beck Depression Inventory-II was used to assess symptoms of depression. Speed of information processing was measured with a Choice Reaction time task. Results: The mean BDI score for patients was significantly higher than the mean score in the general population. Twenty one percent of participants scored in the moderate/severe range. A Cognitive-Affective score and a Somatic-Motivational score was calculated for each patient. Patients’ scores in both dimensions were significantly higher than the scores in the general population. Demographic and disease variables were not related with symptoms of depression, except for severity of ataxia. Depressive symptoms predict cognitive reaction times. The greater proportion of variance was explained by the Cognitive-Affective dimension. Conclusions: Our data show that both somatic-motivational and cognitive affective symptoms of depression are frequent in individuals with FRDA. In addition, depressive symptoms may influence cognition, especially, the cognitive and affective symptoms.     

Pure optic ataxia and visual hemiagnosia – extending the dual visual hypothesis

Goodale and Milner's two visual system hypothesis is an influential model for the understanding of the primate visual system. Lesions of either the ventral (occipito‐temporal) or the dorsal (occipito‐parietal) stream produce distinct and dissociated syndromes in humans: visual agnosia is typical for ventral damage, whereas optic ataxia (OA) for dorsal damage. We studied the case of a 59‐year‐old left‐handed woman with a circumscribed lesion around the left posterior occipital sulcus, extending to the underlying white matter. Initially, she presented with a central visual field OA, which regressed to an OA to the right visual hemifield during the 3 months observation period. In addition, tachistoscopic experiments showed visual hemiagnosia to the right visual hemifield. In line with the findings of the neuropsychological experiments, the analysis of the structural MR data by means of a trackwise hodologic probabilistic approach revealed damage to the left superior longitudinal fasciculus and to the left inferior longitudinal fasciculus, indicating an impairment of both the dorsal and the ventral stream. The combination of OA and visual hemiagnosia in the same patient has never been previously described. The present case study thus provides further insights for the understanding of visual processing.     

Decreased functional brain activation in Friedreich ataxia using the Simon effect task

The present study applied the Simon effect task to examine the pattern of functional brain reorganization in individuals with Friedreich ataxia (FRDA), using functional magnetic resonance imaging (fMRI). Thirteen individuals with FRDA and 14 age and sex matched controls participated, and were required to respond to either congruent or incongruent arrow stimuli, presented either to the left or right of a screen, via laterally-located button press responses. Although the Simon effect (incongruent minus congruent stimuli) showed common regions of activation in both groups, including the superior and middle prefrontal cortices, insulae, superior and inferior parietal lobules (LPs, LPi), occipital cortex and cerebellum, there was reduced functional activation across a range of brain regions (cortical, subcortical and cerebellar) in individuals with FRDA. The greater Simon effect behaviourally in individuals with FRDA, compared with controls, together with concomitant reductions in functional brain activation and reduced functional connectivity between cortical and sub-cortical regions, implies a likely disruption of cortico-cerebellar loops and ineffective engagement of cognitive/attention regions required for response suppression.     

Recommendations from Multi-disciplinary Focus Groups on Cascade Testing and Genetic Counseling for Fragile X-associated Disorders

The purpose of this paper is to report the outcome of a collaborative project between the Fragile X Research and Treatment Center at the Medical Investigation of Neurodevelopmental Disorders (M.I.N.D.) Institute at the University of California at Davis, the National Fragile X Foundation (NFXF), and the Centers for Disease Control and Prevention (CDC). The objective of this collaboration was to develop and disseminate protocols for genetic counseling and cascade testing for the multiple disorders associated with the fragile X mental retardation 1 (FMR1) mutation. Over the last several years, there has been increasing insight into the phenotypic range associated with both the premutation and the full mutation of the FMR1 gene. To help develop recommendations related to screening for fragile X-associated disorders, four, two day advisory focus group meetings were conducted, each with a different theme. The four themes were: (1) fragile X-associated tremor/ataxia syndrome (FXTAS); (2) premature ovarian failure (POF) and reproductive endocrinology; (3) psychiatric, behavioral and psychological issues; and (4) population screening and related ethical issues.     

Lifespan changes in working memory in fragile X premutation males

Fragile X syndrome is the world’s most common hereditary cause of developmental delay in males and is now well characterized at the biological, brain and cognitive levels. The disorder is caused by the silencing of a single gene on the X chromosome, the FMR1 gene. The premutation (carrier) status, however, is less well documented but has an emerging literature that highlights a more subtle profile of executive cognitive deficiencies that mirror those reported in fully affected males. Rarely, however, has the issue of age-related declines in cognitive performance in premutation males been addressed. In the present study, we focus specifically on the cognitive domain of working memory and its subcomponents (verbal, spatial and central executive memory) and explore performance across a broad sample of premutation males aged 18–69 years matched on age and IQ to unaffected comparison males. We further tease apart the premutation status into those males with symptoms of the newly identified neurodegenerative disorder, the fragile X-associated tremor/ataxia syndrome (FXTAS) and those males currently symptom-free. Our findings indicate a specific vulnerability in premutation males on tasks that require simultaneous manipulation and storage of new information, so-called executive control of memory. Furthermore, this vulnerability appears to exist regardless of the presence of FXTAS symptoms. Males with FXTAS symptoms demonstrated a more general impairment encompassing phonological working memory in addition to central executive working memory. Among asymptomatic premutation males, we observed the novel finding of a relationship between increased CGG repeat size and impairment to central executive working memory.     

Impaired inhibition of prepotent motor tendencies in Friedreich ataxia demonstrated by the Simon interference task

Friedreich ataxia (FRDA) is the most common of the genetically inherited ataxias. We recently demonstrated that people with FRDA have impairment in motor planning - most likely because of pathology affecting the cerebral cortex and/or cerebello-cortical projections. We used the Simon interference task to examine how effective 13 individuals with FRDA were at inhibiting inappropriate automatic responses associated with stimulus-response incompatibility in comparison with control participants. Participants had to respond to arrow targets according to two features which were either congruent or incongruent. We found that individuals with FRDA were differentially affected in reaction time to incongruent, compared with congruent stimuli, when compared with control participants. There was a significant negative correlation between age of onset and the incongruency effect, suggesting an impact of FRDA on the developmental unfolding of motor cognition, independent of the effect of disease duration. Future neuroimaging studies will be required to establish whether this dysfunction is due to cerebellar impairment disrupting cerebro-ponto-cerebello-thalamo-cerebral loops (and thus cortical function), direct primary cortical pathology, or a possible combination of the two.     

Speech in spinocerebellar ataxia

Spinocerebellar ataxias (SCAs) are a heterogeneous group of autosomal dominant cerebellar ataxias clinically characterized by progressive ataxia, dysarthria and a range of other concomitant neurological symptoms. Only a few studies include detailed characterization of speech symptoms in SCA. Speech symptoms in SCA resemble ataxic dysarthria but symptoms related to phonation may be more prominent. One study to date has shown an association between differences in speech and voice symptoms related to genotype. More studies of speech and voice phenotypes are motivated, to possibly aid in clinical diagnosis. In addition, instrumental speech analysis has been demonstrated to be a reliable measure that may be used to monitor disease progression or therapy outcomes in possible future pharmacological treatments.     

Psychological Follow-up of Presymptomatic Genetic Testing for Spinocerebellar Ataxia Type 2 (SCA2) in Cuba

Presymptomatic testing for spinocerebellar ataxia type 2 (SCA2) in Cuba started five years ago. We have now investigated the psychological impact of test results on 150 individuals at 50% risk for SCA2. In a prospective study, psychological instruments were used to evaluate depression, anxiety and family functioning (1) before testing and (2) one year after disclosure of the test result. One year after, anxiety and depression levels decreased both in carriers and non-carriers, but anxiety decreased significantly more in carriers. Pathological levels of anxiety were seen mostly in members of dysfunctional families, but decreased more in them than in other consultands. Presymptomatic testing thus seems to have been especially beneficial for these testees, possibly due to a greater gain from the psychosocial support received. It would be pertinent to evaluate now the impact of other psychosocial variables and perform longer-term longitudinal studies.