Microstructural MRI basis of the cognitive functions in patients with Spinocerebellar ataxia type 2

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disease involving the cerebellum. The particular atrophy pattern results in some typical clinical features mainly including motor deficits. In addition, the presence of cognitive impairments, involving language, visuospatial and executive functions, has been also shown in SCA2 patients and it is now widely accepted as a feature of the disease. The aim of the study is to investigate the microstructural patterns and the anatomo-functional substrate that could account for the cognitive symptomatology observed in SCA2 patients. In the present study, diffusion tensor imaging (DTI) based-tractography was performed to map the main cerebellar white matter (WM) bundles, such as Middle and Superior Cerebellar Peduncles, connecting cerebellum with higher order cerebral regions. Damage-related diffusivity measures were used to determine the pattern of pathological changes of cerebellar WM microstructure in patients affected by SCA2 and correlated with the patients' cognitive scores. Our results provide the first evidence that WM diffusivity is altered in the presence of the cerebellar cortical degeneration associated with SCA2 thus resulting in a cerebello-cerebral dysregulation that may account for the specificity of cognitive symptomatology observed in patients

Neural substrates of motor and cognitive dysfunctions in SCA2 patients: a network based statistics analysis

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disease characterized by a progressive cerebellar syndrome, which can be isolated or associated with extracerebellar signs. It has been shown that patients affected by SCA2 present also cognitive impairments and psychiatric symptoms. The cerebellum is known to modulate cortical activity and to contribute to distinct functional networks related to higher-level functions beyond motor control. It is therefore conceivable that one or more networks, rather than isolated regions, may be dysfunctional in cerebellar degenerative diseases and that an abnormal connectivity within specific cerebello-cortical regions might explain the widespread deficits typically observed in patients. In the present study, the network-based statistics (NBS) approach was used to assess differences in functional connectivity between specific cerebellar and erebral “nodes” in SCA2 patients. Altered inter-nodal connectivity was found between more posterior regions in the cerebellum and regions in the cerebral cortex clearly related to cognition and emotion. Furthermore, more anterior cerebellar lobules showed altered inter-nodal connectivity with motor and somatosensory cerebral regions. The present data suggest that in SCA2 a cerebellar dysfunction affects long-distance cerebral regions and that the clinical symptoms may be specifically related with connectivity changes between motor and non-motor cerebello-cortical nodes

Structural cerebellar correlates of cognitive functions in spinocerebellar ataxia type 2

Spinocerebellar ataxia type 2 (SCA2) is an autosomal dominant neurodegenerative disease involving the cerebellum and characterized by a typical motor syndrome. In addition, the presence of cognitive impairment is now widely acknowledged as a feature of SCA2. Given the extensive connections between the cerebellum and associative cerebral areas, it is reasonable to hypothesize that cerebellar neurodegeneration associated with SCA2 may impact on the cerebellar modulation of the cerebral cortex, thus resulting in functional impairment. The aim of the present study was to investigate and quantitatively map the pattern of cerebellar gray matter (GM) atrophy due to SCA2 neurodegeneration and to correlate that with patients' cognitive performances. Cerebellar GM maps were extracted and compared between SCA2 patients (n = 9) and controls (n = 33) by using voxel-based morphometry. Furthermore, the relationship between cerebellar GM atrophy and neuropsychological scores of the patients was assessed. Specific cerebellar GM regions were found to be affected in patients. Additionally, GM loss in cognitive posterior lobules (VI, Crus I, Crus II, VIIB, IX) correlated with visuospatial, verbal memory and executive tasks, while additional correlations with motor anterior (V) and posterior (VIIIA, VIIIB) lobules were found for the tasks engaging motor and planning components. Our results provide evidence that the SCA2 neurodegenerative process affects the cerebellar cortex and that MRI indices of atrophy in different cerebellar subregions may account for the specificity of cognitive symptomatology observed in patients, as result of a cerebello-cerebral dysregulation

An Accurate and Rapidly Calibrating Speech Neuroprosthesis

BackgroundBrain-computer interfaces can enable communication for people with paralysis by transforming cortical activity associated with attempted speech into text on a computer screen. Communication with brain-computer interfaces has been restricted by extensive training requirements and limited accuracy.MethodsA 45-year-old man with amyotrophic lateral sclerosis (ALS) with tetraparesis and severe dysarthria underwent surgical implantation of four microelectrode arrays into his left ventral precentral gyrus 5 years after the onset of the illness; these arrays recorded neural activity from 256 intracortical electrodes. We report the results of decoding his cortical neural activity as he attempted to speak in both prompted and unstructured conversational contexts. Decoded words were displayed on a screen and then vocalized with the use of text-to-speech software designed to sound like his pre-ALS voice.ResultsOn the first day of use (25 days after surgery), the neuroprosthesis achieved 99.6% accuracy with a 50-word vocabulary. Calibration of the neuroprosthesis required 30 minutes of cortical recordings while the participant attempted to speak, followed by subsequent processing. On the second day, after 1.4 additional hours of system training, the neuroprosthesis achieved 90.2% accuracy using a 125,000-word vocabulary. With further training data, the neuroprosthesis sustained 97.5% accuracy over a period of 8.4 months after surgical implantation, and the participant used it to communicate in self-paced conversations at a rate of approximately 32 words per minute for more than 248 cumulative hours.ConclusionsIn a person with ALS and severe dysarthria, an intracortical speech neuroprosthesis reached a level of performance suitable to restore conversational communication after brief training. (Funded by the Office of the Assistant Secretary of Defense for Health Affairs and others; BrainGate2 ClinicalTrials.gov number, NCT00912041.)

Basic income and the right to work: a Keynesian approach

Among the proposals for radical reform of social policy are basic income, which would pay an unconditional cash benefit to all individuals, and the right to work, which would offer guaranteed employment arranged by the state if necessary. This paper examines the macroeconomic consequences of such reform proposals. It sets up a simple Keynesian income-expenditure model that includes basic income and the right to work as alternative methods of providing social assistance, along with the more traditional approach of paying unemployment benefits. The various schemes are compared and contrasted with regard to their implications for employment, stability, distribution, efficiency and the government budget. Potential benefits of basic income or the right to work are emphasised, despite the political obstacles to implementing them

A labour turnover cost model of market segmentation and statistical discrimination

SIGLEAvailable from British Library Document Supply Centre- DSC:7755.0054(CU-FEP-RP--45) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The Development of Shyness from Late Childhood to Adolescence: A Longitudinal Study of Mexican-origin Youth

Shyness, or the tendency to be inhibited and uncomfortable in novel social situations, is a consequential personality trait, especially during adolescence. The present study examined the development of shyness from late childhood (age 10) through adolescence (age 16) using data from a large, longitudinal study of Mexican-origin youth (N = 674). Using both self- and mother-reports of shyness assessed via the Early Adolescent Temperament Questionnaire-Revised, we found moderate to high rank-order stabilities across two-year intervals and a mean-level decrease in shyness from age 10 to 16. Anxiety and depression were associated with higher initial levels of shyness, and anxiety was associated with greater decreases in shyness from age 10 to 16. Contrary to predictions, neither nativity (country of birth) nor language proficiency (English, Spanish) was associated with the development of shyness across adolescence. Thus, youth generally decline in shyness during adolescence, although there is substantial individual variability in shyness trajectories

Segmented labour market theory Definitional issues from a choice-theoretic perspective

SIGLEAvailable from British Library Document Supply Centre- DSC:7755.054(CU-FEP-RP--41) / BLDSC - British Library Document Supply CentreGBUnited Kingdo

The Development of Shyness from Late Childhood to Adolescence: A Longitudinal Study of Mexican-origin Youth

Shyness, or the tendency to be inhibited and uncomfortable in novel social situations, is a consequential personality trait, especially during adolescence. The present study examined the development of shyness from late childhood (age 10) through adolescence (age 16) using data from a large, longitudinal study of Mexican-origin youth (N = 674). Using both self- and mother-reports of shyness assessed via the Early Adolescent Temperament Questionnaire-Revised, we found moderate to high rank-order stabilities across two-year intervals and a mean-level decrease in shyness from age 10 to 16. Anxiety and depression were associated with higher initial levels of shyness, and anxiety was associated with greater decreases in shyness from age 10 to 16. Contrary to predictions, neither nativity (country of birth) nor language proficiency (English, Spanish) was associated with the development of shyness across adolescence. Thus, youth generally decline in shyness during adolescence, although there is substantial individual variability in shyness trajectories

Intra-Aortic Balloon Counterpulsation for the Treatment of Ischemic Stroke

Colloid volume expansion has been shown to increase cerebral blood flow to ischemic brain in an animal stroke model and improve recovery in patients. It is, however, potentially hazardous to use in older patients because of frequently associated cardiovascular disease. Intra-Aortic Balloon Counterpulsation might reduce the risks of using volume expansion therapy in the elderly patient. This study was designed to see if Intra-Aortic Balloon Counterpulsation (without volume expansion), in an animal with a normal heart, would increase cerebral blood flow and EEG activity in the ischemic brain. Unilateral cerebral ischemia was produced in baboons (n = 9) after right middle cerebral artery occlusion. A 12 ml intra-aortic balloon catheter was introduced into the descending aorta via the femoral artery prior to middle cerebral artery occlusion. The balloon was positioned distal to the origin of the left subclavian artery and following middle cerebral artery occlusion was inflated with each R wave on the ECG. Cardiac output, cerebral blood flow (by Hydrogen wash-out), computer-mapped EEG, and hemodynamic data were collected prior to middle cerebral artery occlusion and following occlusion both before and during counterpulsation. Intra-Aortic Balloon Counterpulsation produced a significant increase in pulse pressure from 54.7 ± 21 to 70.6 ± 33 mmHg (p = .043). No significant change was seen in cardiac output, mean arterial pressure, or cerebral blood flow. Although the computer- mapped EEG improved and the right (ischemic) hemisphere cerebral blood flow did increase slightly from 16.9 ± 6.5 to 18.3 ± 8.3 ml/100 gm/min, the cerebral blood flow changes were not significant (p=.295). It is possible that the desired increase in cerebral blood flow was not achieved partly because the animals were only 3-4 years old and were difficult to stroke. We believe that there is merit to a follow-up study in older primates with colloid volume expansion where Intra-Aortic Balloon Counterpulsation is used to protect the heart from the deleterious effects of volume expansion and where the cardiac effects of volume expansion and counterpulsation are quantified. Perhaps volume expansion with Intra-Aortic Balloon Counterpulsation will be safer and more effective than either treatment modality alone. (All data reported as mean ± standard deviation