Quantitative assessment based on kinematic measures of functional impairments during upper extremity movements: a review

Quantitative measures of human movement quality are important for discriminating healthy and pathological conditions and for expressing the outcomes and clinically important changes in subjects' functional state. However the most frequently used instruments for the upper extremity functional assessment are clinical scales, that previously have been standardized and validated, but have a high subjective component depending on the observer who scores the test. But they are not enough to assess motor strategies used during movements, and their use in combination with other more objective measures is necessary. The objective of the present review is to provide an overview on objective metrics found in literature with the aim of quantifying the upper extremity performance during functional tasks, regardless of the equipment or system used for registering kinematic data.

Insertion of impairments in test video sequences for quality assessment based on psychovisual characteristics

Assessing video quality is a complex task. While most pixel-based metrics do not present enough correlation between objective and subjective results, algorithms need to correspond to human perception when analyzing quality in a video sequence. For analyzing the perceived quality derived from concrete video artifacts in determined region of interest we present a novel methodology for generating test sequences which allow the analysis of impact of each individual distortion. Through results obtained after subjective assessment it is possible to create psychovisual models based on weighting pixels belonging to different regions of interest distributed by color, position, motion or content. Interesting results are obtained in subjective assessment which demonstrates the necessity of new metrics adapted to human visual system.

Lack of tissue glucocorticoid reactivation in 11β-hydroxysteroid dehydrogenase type 1 knockout mice ameliorates age-related learning impairments

11β-hydroxysteroid dehydrogenase type 1 (11β-HSD-1) intracellularly regenerates active corticosterone from circulating inert 11-dehydrocorticosterone (11-DHC) in specific tissues. The hippocampus is a brain structure particularly vulnerable to glucocorticoid neurotoxicity with aging. In intact hippocampal cells in culture, 11β-HSD-1 acts as a functional 11β-reductase reactivating inert 11-DHC to corticosterone, thereby potentiating kainate neurotoxicity. We examined the functional significance of 11β-HSD-1 in the central nervous system by using knockout mice. Aged wild-type mice developed elevated plasma corticosterone levels that correlated with learning deficits in the watermaze. In contrast, despite elevated plasma corticosterone levels throughout life, this glucocorticoid-associated learning deficit was ameliorated in aged 11β-HSD-1 knockout mice, implicating lower intraneuronal corticosterone levels through lack of 11-DHC reactivation. Indeed, aged knockout mice showed significantly lower hippocampal tissue corticosterone levels than wild-type controls. These findings demonstrate that tissue corticosterone levels do not merely reflect plasma levels and appear to play a more important role in hippocampal functions than circulating blood levels. The data emphasize the crucial importance of local enzymes in determining intracellular glucocorticoid activity. Selective 11β-HSD-1 inhibitors may protect against hippocampal function decline with age.

Long-term functional recovery from age-induced spatial memory impairments by nerve growth factor gene transfer to the rat basal forebrain.

Nerve growth factor (NGF) stimulates functional recovery from cognitive impairments associated with aging, either when administered as a purified protein or by means of gene transfer to the basal forebrain. Because gene transfer procedures need to be tested in long-term experimental paradigms to assess their in vivo efficiency, we have used ex vivo experimental gene therapy to provide local delivery of NGF to the aged rat brain over a period of 2.5 months by transplanting immortalized central nervous system-derived neural stem cells genetically engineered to secrete NGF. By grafting them at two independent locations in the basal forebrain, medial septum and nucleus basalis magnocellularis, we show that functional recovery as assessed in the Morris water maze can be achieved by neurotrophic stimulation of any of these cholinergic cell groups. Moreover, the cholinergic neurons in the grafted regions showed a hypertrophic response resulting in a reversal of the age-associated atrophy seen in the learning-impaired aged control rats. Long-term expression of the transgene lead to an increased NGF tissue content (as determined by NGF-ELISA) in the transplanted regions up to at least 10 weeks after grafting. We conclude that the gene transfer procedure used here is efficient to provide the brain with a long-lasting local supply of exogenous NGF, induces long-term functional recovery of cognitive functions, and that independent trophic stimulation of the medial septum or nucleus basalis magnocellularis has similar consequences at the behavioral level.

7-Chloro-3-methyl-3,4-dihydro-2H-1,2,4-benzothiadiazine S,S-dioxide (IDRA 21), a congener of aniracetam, potently abates pharmacologically induced cognitive impairments in patas monkeys.

We report here on the ability of IDRA 21 and aniracetam, two negative allosteric modulators of glutamate-induced DL-alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor desensitization, to attenuate alprazolam-induced learning deficit in patas monkeys working in a complex behavioral task. In one component of a multiple schedule (repeated acquisition or "learning"), patas monkeys acquired a different four-response chain each session by responding sequentially on three keys in the presence of four discriminative stimuli (geometric forms or numerals). In the other component (performance) the four-response chain was the same each session. The response chain in each component was maintained by food presentation under a fixed-ratio schedule. When alprazolam (0.1 or 0.32 mg/kg p.o.) was administered alone, this full allosteric modulator of gamma-aminobutyric acid type A (GABAA) receptors produced large decreases in the response rate and accuracy in the learning component of the task. IDRA 21 (3 or 5.6 mg/kg p.o.) and aniracetam (30 mg/kg p.o.) administered 60 min before alprazolam, having no effect when given alone, antagonized the large disruptive effects of alprazolam on learning. From dose-response studies, it can be estimated that IDRA 21 is approximately 10-fold more potent than aniracetam in antagonizing alprazolam-induced learning deficit. We conclude that IDRA 21, a chemically unrelated pharmacological congener of aniracetam, improves learning deficit induced in patas monkeys by the increase of GABAergic tone elicited by alprazolam. Very likely IDRA 21 exerts its behavioral effects by antagonizing AMPA receptor desensitization.

Sighted volunteers’ motivations to assist people with visual impairments in freetime sport activities

Since the changing of the political and economic system in 1989-1990 in Hungary, volunteer movements have appeared all over the country. Volunteers of different ages and socioeconomic backgrounds are engaged in a wide range of activities, wishing to add values to the lives of others in need, hoping to improve their micro or/and macro environment. Volunteering has also appeared in the field of sport, and the work of a large number of nongovernmental sport organisations is strongly dependent on volunteers’ participation. In the socialist era disability sports were neglected by the state. The new democratic state has been paying increasing attention to disability sports and volunteers have been a great asset in improving the accessibility of spare time sport activities. The present empirical research investigates which factors motivate sighted volunteers to join Hungarian Sports and Leisure Association for the Visually Impaired (Látássérültek Szabadidős Sportegyesülete, LÁSS). Results confirm that joining LÁSS was in few cases (N=3) attributed to having parental or other family relations with blind or partially sighted people. Respondents unanimously admit to have a wish to share the joy of physical activity with their visually impaired peers.

Mitochondrial impairments contribute to Spinocerebellar ataxia type 1 progression and can be ameliorated by the mitochondria-targeted antioxidant MitoQ

Spinocerebellar ataxia type 1 (SCA1), due to an unstable polyglutamine expansion within the ubiquitously expressed Ataxin-1 protein, leads to the premature degeneration of Purkinje cells (PCs), decreasing motor coordination and causing death within 10-15 years of diagnosis. Currently, there are no therapies available to slow down disease progression. As secondary cellular impairments contributing to SCA1 progression are poorly understood, here, we focused on identifying those processes by performing a PC specific proteome profiling of Sca1154Q/2Q mice at a symptomatic stage. Mass spectrometry analysis revealed prominent alterations in mitochondrial proteins. Immunohistochemical and serial block-face scanning electron microscopy analyses confirmed that PCs underwent age-dependent alterations in mitochondrial morphology. Moreover, colorimetric assays demonstrated impairment of the electron transport chain complexes (ETC) and decrease in ATPase activity. Subsequently, we examined whether the mitochondria-targeted antioxidant MitoQ could restore mitochondrial dysfunction and prevent SCA1-associated pathology in Sca1154Q/2Q mice. MitoQ treatment both presymptomatically and when symptoms were evident ameliorated mitochondrial morphology and restored the activities of the ETC complexes. Notably, MitoQ slowed down the appearance of SCA1-linked neuropathology such as lack of motor coordination as well as preventing oxidative stress-induced DNA / RNA damage and PC loss. Our work identifies a central role for mitochondria in PC degeneration in SCA1 and provides evidence for the supportive use of mitochondria-targeted therapeutics in slowing down disease progression.

Detectable warnings: detectability by individuals with visual impairments, and safety and negotiability on slopes for persons with physical impairments. Final report.

Federal Transit Administration, Washington, D.C.

Lexical and nonlexical processing in developmental dyslexia: a case for different resources and different impairments

In a group of adult dyslexics word reading and, especially, word spelling are predicted more by what we have called lexical learning (tapped by a paired-associate task with pictures and written nonwords) than by phonological skills. Nonword reading and spelling, instead, are not associated with this task but they are predicted by phonological tasks. Consistently, surface and phonological dyslexics show opposite profiles on lexical learning and phonological tasks. The phonological dyslexics are more impaired on the phonological tasks, while the surface dyslexics are equally or more impaired on the lexical learning tasks. Finally, orthographic lexical learning explains more variation in spelling than in reading, and subtyping based on spelling returns more interpretable results than that based on reading. These results suggest that the quality of lexical representations is crucial to adult literacy skills. This is best measured by spelling and best predicted by a task of lexical learning. We hypothesize that lexical learning taps a uniquely human capacity to form new representations by recombining the units of a restricted set.

Compensation of intra-channel nonlinear fibre impairments using simplified digital back-propagation algorithm

We investigate a digital back-propagation simplification method to enable computationally-efficient digital nonlinearity compensation for a coherently-detected 112 Gb/s polarization multiplexed quadrature phase shifted keying transmission over a 1,600 km link (20x80km) with no inline compensation. Through numerical simulation, we report up to 80% reduction in required back-propagation steps to perform nonlinear compensation, in comparison to the standard back-propagation algorithm. This method takes into account the correlation between adjacent symbols at a given instant using a weighted-average approach, and optimization of the position of nonlinear compensator stage to enable practical digital back-propagation.

Compensation of nonlinear fibre impairments in coherent systems employing spectrally efficient modulation formats

We investigate electronic mitigation of linear and non-linear fibre impairments and compare various digital signal processing techniques, including electronic dispersion compensation (EDC), single-channel back-propagation (SC-BP) and back-propagation with multiple channel processing (MC-BP) in a nine-channel 112 Gb/s PM-mQAM (m=4,16) WDM system, for reaches up to 6,320 km. We show that, for a sufficiently high local dispersion, SC-BP is sufficient to provide a significant performance enhancement when compared to EDC, and is adequate to achieve BER below FEC threshold. For these conditions we report that a sampling rate of two samples per symbol is sufficient for practical SC-BP, without significant penalties.