Effects of muscle fibre shortening on the characteristics of surface motor unit potentials.

Traditionally, studies dealing with muscle shortening have concentrated on assessing its impact on conduction velocity, and to this end, electrodes have been located between the end-plate and tendon regions. Possible morphologic changes in surface motor unit potentials (MUPs) as a result of muscle shortening have not, as yet, been evaluated or characterized. Using a convolutional MUP model, we investigated the effects of muscle shortening on the shape, amplitude, and duration characteristics of MUPs for different electrode positions relative to the fibre-tendon junction and for different depths of the MU in the muscle (MU-to-electrode distance). It was found that the effects of muscle shortening on MUP morphology depended not only on whether the electrodes were between the end-plate and the tendon junction or beyond the tendon junction, but also on the specific distance to this junction. When the electrodes lie between the end-plate and tendon junction, it was found that (1) the muscle shortening effect is not important for superficial MUs, (2) the sensitivity of MUP amplitude to muscle shortening increases with MU-to-electrode distance, and (3) the amplitude of the MUP negative phase is not affected by muscle shortening. This study provides a basis for the interpretation of the changes in MUP characteristics in experiments where both physiological and geometrical aspects of the muscle are varied.

Stimulus-response curve of human motor nerves: multicenter assessment of various indexes.

The value of various indexes to characterize the stimulus-response curve of human motor nerves was assessed in 40 healthy subjects recruited from four European centers of investigation (Créteil, Lausanne, Liège, Marseille). Stimulus-response curves were established by stimulating the right median and ulnar motor nerves at the wrist, with stimulus durations of 0.05 and 0.5 ms. The following parameters were studied: the threshold intensity of stimulation to obtain 10% (I 10), 50% (I 50), and 90% (I 90) of the maximal compound muscle action potential, the ratios I 10/I 50, I 90/I 50, (I 90 - I 10)/I 10, (I 90-I 50)/I 50, and (I 50 - I 10)/I 10, and the slopes of the stimulus-response curves with or without normalization to I 50. For each parameter, within-center variability and reproducibility (in a test-retest study) were assessed and between-center comparisons were made. For most of the parameters, the results varied significantly within and between the centers. Within the centers, only the ratios I 10/I 50 and I 90/I 50 were found constant and reproducible. Between the centers, the absolute intensity thresholds (I 10, I 50, I 90) and the ratio I 90/I 50 did not show significant differences at stimulus duration of 0.5 ms, whatever the stimulated nerve. The reduced variability and good reproducibility of the ratios I 10/I 50 and I 90/I 50 open perspectives in neurophysiological practice for the use of these indexes of the stimulus-response curve, a rapid and noninvasive test.

Maria-Mercè Marçal en el mirall : sobre l'imaginari femení i el llenguatge poètic

Per Maria-Mercè Marçal, la poeta no es pot trobar, no es pot veure, en el «mirall del bell», que sempre han fomentat els discursos dominants. El seu és una altra mena de mirall trencat que reflecteix un ésser complex, híbrid i contaminat que lluita «entre un jo que es vol fer i els múltiples personatges que, des del mirall, li retornen una imatge múltiple». En aquest article, per explorar el tema de l’imaginari femení i el llenguatge poètic, hem escollit dialogar amb Maria- Mercè Marçal i examinar tres dels múltiples bocins que conformen la seva imatge en el mirall. Conversem amb dues mares i un pare simbòlics de l’altre cantó del seu espill, tots tres proveïdors de material ideològic i eixos vertebradors dels assaigs marçalians. Es tracta d’intel·lectuals ben diversos: l’escriptora anglesa Virginia Woolf, el filòsof francès Jacques Derrida i la poeta catalana Maria-Antònia Salvà. En definitiva, dividim la investigació en tres apartats, que volen coincidir amb el diàleg que Marçal suposem que hi mantingué. De primer, amb Virginia Woolf, explorem la necessitat de la poeta de descobrir el sentiment de «fúria» que porta a dins per tal d’assumir la irracionalitat del seu llenguatge. Després, ens endinsem en les teories derridianes sobre la dona i l’escriptura, en un intent de demostrar que ambdues són espècies híbrides que viuen en el llindar, en un espai d’entremig. A l’últim, amb Maria-Antònia Salvà, revisem la imatge de la dona-monstre amb la certesa que «el salvatge» i «l’incert » són el motor del llenguatge poètic femení.

Issue review : Iowa State Patrol and the Office of Motor Vehicle Enforcement potential integration.

This issue review analyzes the duties and responsibilities of troopers in the Iowa State Patrol, or ISP, and Motor Vehicle Enforcement, MVE, officers in the Department of Transportation, or DOT, as well as the differences such as funding, pay and pension. In addition, this issue review discusses the proposal for a potential integration of the offices under one system.

The "handwriting brain": a meta-analysis of neuroimaging studies of motor versus orthographic processes.

INTRODUCTION: Handwriting is a modality of language production whose cerebral substrates remain poorly known although the existence of specific regions is postulated. The description of brain damaged patients with agraphia and, more recently, several neuroimaging studies suggest the involvement of different brain regions. However, results vary with the methodological choices made and may not always discriminate between "writing-specific" and motor or linguistic processes shared with other abilities. METHODS: We used the "Activation Likelihood Estimate" (ALE) meta-analytical method to identify the cerebral network of areas commonly activated during handwriting in 18 neuroimaging studies published in the literature. Included contrasts were also classified according to the control tasks used, whether non-specific motor/output-control or linguistic/input-control. These data were included in two secondary meta-analyses in order to reveal the functional role of the different areas of this network. RESULTS: An extensive, mainly left-hemisphere network of 12 cortical and sub-cortical areas was obtained; three of which were considered as primarily writing-specific (left superior frontal sulcus/middle frontal gyrus area, left intraparietal sulcus/superior parietal area, right cerebellum) while others related rather to non-specific motor (primary motor and sensorimotor cortex, supplementary motor area, thalamus and putamen) or linguistic processes (ventral premotor cortex, posterior/inferior temporal cortex). CONCLUSIONS: This meta-analysis provides a description of the cerebral network of handwriting as revealed by various types of neuroimaging experiments and confirms the crucial involvement of the left frontal and superior parietal regions. These findings provide new insights into cognitive processes involved in handwriting and their cerebral substrates.

Increased alpha activity and modulations of fronto-parietal balance during motor transitions in the elderly

A hallmark of aging is the sensorimotor deficit, characterized by an increased reaction time and a reduction of motor abilities. Some mechanisms such as motor inhibition deteriorate with aging because of neuronal density alterations and modifications of connections between brain regions. These deficits may be compensated throughout a recruitment of additional areas. Studies have shown that old adults have increased difficulty in performing bimanual coordination tasks compared with young adults. In contrast, motor switching is poorly documented and is expected to engage increasing resources in the elderly. The present study examines performances and electro-cortical correlates of motor switching in young and elderly adults.

Desenvolupament d'un motor 2D per videojocs de plataformes mòbils

L’objectiu del projecte és la creació d’un motor gràfic id’esdeveniments per a jocs RPG per a plataformes mòbils, en aquest casper a Nintendo DS. S’ha de remarcar que el que s’està proposant no és laprogramació d’un videojoc, sinó que el que es desenvoluparà és el motorde joc. Aquest motor comptarà no solament amb la funcionalitat bàsica devisualització i animació d’escenaris i personatges, detecció de col•lisionsentre personatges i elements de l’escenari, sinó que a més, comptarà ambles funcionalitats pròpies dels jocs més sofisticats (esdeveniments). Aquestmotor és compatible per a Nintendo DS i/o qualsevol emulador d’aquestaplataforma per a PC

RNA interference mitigates motor and neuropathological deficits in a cerebellar mouse model of machado-joseph disease.

Machado-Joseph disease or Spinocerebellar ataxia type 3 is a progressive fatal neurodegenerative disorder caused by the polyglutamine-expanded protein ataxin-3. Recent studies demonstrate that RNA interference is a promising approach for the treatment of Machado-Joseph disease. However, whether gene silencing at an early time-point is able to prevent the appearance of motor behavior deficits typical of the disease when initiated before onset of the disease had not been explored. Here, using a lentiviral-mediated allele-specific silencing of mutant ataxin-3 in an early pre-symptomatic cerebellar mouse model of Machado-Joseph disease we show that this strategy hampers the development of the motor and neuropathological phenotypic characteristics of the disease. At the histological level, the RNA-specific silencing of mutant ataxin-3 decreased formation of mutant ataxin-3 aggregates, preserved Purkinje cell morphology and expression of neuronal markers while reducing cell death. Importantly, gene silencing prevented the development of impairments in balance, motor coordination, gait and hyperactivity observed in control mice. These data support the therapeutic potential of RNA interference for Machado-Joseph disease and constitute a proof of principle of the beneficial effects of early allele-specific silencing for therapy of this disease.

A structural MRI study of motor conversion disorder: evidence of reduction in thalamic volume.

OBJECTIVE: To investigate potential abnormalities in subcortical brain structures in conversion disorder (CD) compared with controls using a region of interest (ROI) approach. METHODS: Fourteen patients with motor CD were compared with 31 healthy controls using high-resolution MRI scans with an ROI approach focusing on the basal ganglia, thalamus and amygdala. Brain volumes were measured using Freesurfer, a validated segmentation algorithm. RESULTS: Significantly smaller left thalamic volumes were found in patients compared with controls when corrected for intracranial volume. These reductions did not vary with handedness, laterality, duration or severity of symptoms. CONCLUSIONS: These differences may reflect a primary disease process in this area or be secondary effects of the disorder, for example, resulting from limb disuse. Larger, longitudinal structural imaging studies will be required to confirm the findings and explore whether they are primary or secondary to CD.

Recent skin injuries in children with motor disabilities.

OBJECTIVE: To determine the frequency of recent skin injuries in children with neuromotor disabilities and its association with disability. DESIGN: Cross-sectional study of 168 children with neuromotor disabilities aged 2-16 years. SETTING: Two outpatient child rehabilitation centres. MAIN OUTCOME MEASURES: Children were classified as unrestricted walkers, restricted walkers or wheelchair dependent. Each participant's body surface was systematically examined for recent skin injuries with the exception of the anal-genital area. RESULTS: The mean age of our sample was 7.8 (SD 3.7) years with a 3:2 male/female ratio. Overall, 64% had cerebral palsy, 17% a neuromuscular disease and 19% other motor disabilities. Participants had on average 5.3 (SD 4.5) recent skin injuries (max 19), of which 2.5 were bruises (SD 3.3, max 16), 2.4 were abrasions, scratches or cuts (SD 3.0, max 16) and 0.4 were pressure lesions (SD 0.8, max 4). There was a significant decrease in the frequency of recent skin injuries and of bruises with increasing severity of motor disability. Most of this variation was accounted for by injuries to the lower limbs. There were no significant effects of gender, learning disabilities or other comorbidities. CONCLUSIONS: Children with neuromotor disabilities present a progressive reduction in the number of skin injuries with decreasing mobility. Therefore, recent skin injuries in this population which are unusual by their number, appearance or distribution, should raise at least the same level of suspicion for physical abuse as in children without disabilities.

Improvement in gross motor performance between 3 and 5 years of age.

This study examined gross motor performance of 101 typically developing children between 3 and 5 years of age (48 boys, 53 girls, M age = 3.9 yr., SD = 0.5). All children performed 7 different gross motor tasks which were rated on a 5-point scale. Age and sex were assessed by an ordinal-logistic model, and odds ratios were calculated for each task using age and sex as covariates. For standing on one leg, walking on a beam, hopping on one leg, running, and taking stairs, statistically significant age differences were found, while for rising and jumping down, none were apparent. Mean motor performance did not differ between boys and girls on the tasks. The older the children were, the better they performed on the tasks.

Evaluation of Iowa's Driver Improvement Program, 2009

This study examines the effectiveness of Iowa’s Driver Improvement Program (DIP), measured as the reduction in the number of driver convictions subsequent to the DIP. The analysis involved a random sample of 9,055 drivers who had been instructed to attend DIP and corresponding data on driver convictions, crashes, and driver education training history that were provided by the Iowa Motor Vehicle Division. The sample was divided into two groups based on DIP outcome: satisfactory or unsatisfactory completion. Two evaluation periods were considered: one year after the DIP date (probation period) and the period from the 13th to 18th month after the DIP date. The evaluation of Iowa’s DIP showed that there is evidence of effectiveness in terms of reducing driver convictions subsequent to attending the DIP. Among the 6,790 (75%) drivers who completed the course satisfactorily, 73% of drivers had no actions and 93% were not involved in a crash during the probation period. Statistical tests confirmed these numbers. However, the positive effect of satisfactory completion of DIP on survival time (that is, the time until the first conviction) was not statistically significant 13 months after the DIP date. Econometric model estimation results showed that, regardless of the DIP outcome, the likelihood of conviction occurrence and frequency of subsequent convictions depends on other factors, such as age, driver history, and DIP location, and interaction effects among these factors. Low-cost, early intervention measures are suggested to enhance the effectiveness of Iowa’s DIP. These measures can include advisory and warning letters (customized based on the driver’s age) sent within the first year after the DIP date and soon after the end of the probation period, as well as a closer examination of DIP instruction across the 17 community colleges that host the program. Given the large number of suspended drivers who continued to drive, consideration should also be given to measures to reduce driving while suspended offenses.

Spatial Scale of Clustering of Motor Vehicle Crash Types and Appropriate Countermeasures, 2009

This project analyzes the characteristics and spatial distributions of motor vehicle crash types in order to evaluate the degree and scale of their spatial clustering. Crashes occur as the result of a variety of vehicle, roadway, and human factors and thus vary in their clustering behavior. Clustering can occur at a variety of scales, from the intersection level, to the corridor level, to the area level. Conversely, other crash types are less linked to geographic factors and are more spatially “random.” The degree and scale of clustering have implications for the use of strategies to promote transportation safety. In this project, Iowa's crash database, geographic information systems, and recent advances in spatial statistics methodologies and software tools were used to analyze the degree and spatial scale of clustering for several crash types within the counties of the Iowa Northland Regional Council of Governments. A statistical measure called the K function was used to analyze the clustering behavior of crashes. Several methodological issues, related to the application of this spatial statistical technique in the context of motor vehicle crashes on a road network, were identified and addressed. These methods facilitated the identification of crash clusters at appropriate scales of analysis for each crash type. This clustering information is useful for improving transportation safety through focused countermeasures directly linked to crash causes and the spatial extent of identified problem locations, as well as through the identification of less location-based crash types better suited to non-spatial countermeasures. The results of the K function analysis point to the usefulness of the procedure in identifying the degree and scale at which crashes cluster, or do not cluster, relative to each other. Moreover, for many individual crash types, different patterns and processes and potentially different countermeasures appeared at different scales of analysis. This finding highlights the importance of scale considerations in problem identification and countermeasure formulation.