The influence of stress and muscle fatigue on implicitly and explicitly learned motor skills

According to Beek (2000), disturbing causes at the upper level of action (i.e. stress) and at the lower level of control (i.e. muscular fatigue) might result in different effects on performance when comparing implicit and explicit learning. In the present experiment an errorless/errorfull learning paradigm was used to enable the implicit/explicit acquisition of a dart throwing skill. After a pretest, the errorfull group (N=23) throwed from a progressively decreasing distance (from 317 to 257 cm), while the inverse procedure was used for the errorless group (N=21) (from 157 to 217 cm). One week after the four-day learning period (400 trials) both groups performed a transfer test, a fatigue test and a stress test (all from 237 cm). The fatigue test was preceded by a double Wingate protocol on an arm crank ergometer. At the beginning of the stress test participants were told they could win a significant financial reward in case of a good performance. Retrospective self-report of nervousness was administered under stressed and unstressed conditions. Hitting accuracy of the errorfull group improved from M=5.29 (maximum=15) in the first learning block to M=7.81 in the final learning block, while the errorless group evolved from M=9.67 to M=8.74, which is typical for an errorless/errorfull learning paradigm. In comparison to the scores at the pre-test both groups performed equally (performance increase of 22%) at the transfer test. Performance of both groups decreased at the fatigue test, but this decrease was much less in the explicit group (5%, ns) as compared to the implicit group (18%, p<.005). Stress manipulation resulted in an increase of self-reported nervousness; however stress did not have a differential impact on performance in both groups. Our results of the fatigue test confirmed the hypothesis of robustness of explicit motor learning to physiological fatigue, meaning that success depends on the person’s ability to circumvent the (temporary) impairment induced by muscular fatigue, and thus develop alternative strategies based upon explicit knowledge. The contradiction with the findings of Poolton et al. (2006) may be due to task specificity and the sort of fatigue induced (local vs. global), which calls for further research on this topic. Our results of the stress test do not show the superiority of implicit or explicit learning when performing under stress

Learning curve assessment of rule use provides evidence for spared implicit sequence learning in a mouse model of mental retardation

Humans with Fragile X Syndrome (FXS) have a mental retardation of which a notable characteristic is a weakness in recalling sequences of information. A mouse model of the disorder exists which exhibits behavioral and neurologic changes, but cognitive testing has not revealed learning deficits seemingly comparable in magnitude to that seen in the human condition. A working memory task for olfactory sequences was employed to test learning set acquisition in mice, half of which had a disruption of the gene responsible for FXS in humans. The task protected against reward detection artifact and demonstrated stringency-dependent task acquisition. A comparable image-based sequence learning set task was used to test humans. The performances of human subjects who did and did not report consciously acquiring the task rules were used as positive and negative controls to assess the mouse learning curves. Learning curve plateau error fluctuation for individual mice was comparable to that of human subjects who never acquired an explicit rule to perform the task, but different from those of human subjects who could state a rule to solve the problem. Sliding window error plots and nonparametric statistical analysis discriminated between the consciously rule-based human performances and that of the mice and humans who did not explicitly obtain the rule. Based on comparison to the human results, wild-type and FX mouse learning curves with a continuingly variable terminal plateau error rate in sliding epochs were classified as “implicit”. Although a moderately large difference in performance of the olfactory task was observed among mouse strains, there was no significant effect of FX genotype. The wild-type performance of the FX mice in this sequence task suggests that implicit learning may be relatively spared in FXS

Memory Rehabilitation Strategies in Nonsurgical Temporal Lobe Epilepsy: A Review

open8siPeople with temporal lobe epilepsy (TLE) who have not undergone epilepsy surgery often complain of memory deficits. Cognitive re- habilitation is employed as a remedial intervention in clinical settings, but research is limited and findings concerning efficacy and the criteria for choosing different approaches have been inconsistent. We aimed to appraise existing evidence on memory rehabilitation in nonsurgical individuals with temporal lobe epilepsy and to ascertain the effectiveness of specific strategies. A scoping review was preferred given the het- erogeneous nature of the interventions. A comprehensive literature search using MEDLINE, EMBASE, CINAHL, AMED, Scholars Portal/ PSYCHinfo, Proceedings First, and ProQuest Dissertations and Theses identified articles published in English before February 2016. The search retrieved 372 abstracts. Of 25 eligible studies, six were included in the final review. None included pediatric populations. Strategies included cognitive training, external memory aids, brain training, and noninvasive brain stimulation. Selection criteria tended to be general. Overall, there was insufficient evidence to make definitive conclusions regarding the efficacy of traditional memory rehabilitation strategies, brain training, and noninvasive brain stimulation. The review suggests that cognitive rehabilitation in nonsurgical TLE is underresearched and that there is a need for a systematic evaluation in this population.embargoed_20180216DEL FELICE, Alessandra; Alderighi, Marzia; Martinato, Matteo; Grisafi, Davide; Bosco, Anna; Thompson, Pamela J.; Sander, Josemir W.; Masiero, StefanoDEL FELICE, Alessandra; Alderighi, Marzia; Martinato, Matteo; Grisafi, Davide; Bosco, Anna; Thompson, Pamela J.; Sander, Josemir W.; Masiero, Stefan

Exploring evidence-based practice by occupational therapists when working with people with apraxia

Short Report Evidence in the literature supports a number of interventions that occupational therapists may utilise when working with people with apraxia, although there is no gold standard approach. A large-scale survey (n = 304, 36% response rate) was conducted with the membership of the College of Occupational Therapists Specialist Section – Neurological Practice to explore therapists’ understanding of apraxia and to provide a benchmark of current practice. Consensus was found in the majority of belief statements regarding the condition, although the respondents were unclear about the relationship between cognition and apraxia. When the therapists were asked to indicate their choice and use of interventions for apraxia, the results showed that the main consideration was the context in which a person performs activities, with moderate use of specific techniques including errorless learning and chaining. The results are related to the evidence base and the implications for occupational therapy practice and education are discussed

A comparison of errorless and errorful therapies for dysgraphia after stroke.

Despite the increasing significance of written communication, there is limited research into spelling therapy for adults with acquired dysgraphia. Existing studies have typically measured spelling accuracy as an outcome, although speed may also be important for functional writing. As spelling is relatively slow, effortful and prone to errors in people with dysgraphia, minimising errors within therapy could be a factor in therapy success. This within-participant case-series study investigated whether errorless and errorful therapies would differ in their effects on spelling speed and accuracy for four participants with acquired dysgraphia. Matched sets of words were treated with errorless or errorful therapy or left untreated. Results were collated one week and five weeks after therapy. Both therapy approaches were successful in improving spelling accuracy. For three participants, equivalent gains were demonstrated following errorless and errorful therapy. One participant made significantly greater improvements in spelling accuracy following errorless therapy. The effects were maintained five weeks later. There was no significant difference in post-therapy spelling speed between the two therapy conditions. The results of this study suggest that both errorful and errorless therapies can be effective methods with which to treat spelling in adults with acquired dysgraphia

Capacity of Complexity-Constrained Noise-Free CDMA

An interference-limited noise-free CDMA downlink channel operating under a complexity constraint on the receiver is introduced. According to this paradigm, detected bits, obtained by performing hard decisions directly on the channel's matched filter output, must be the same as the transmitted binary inputs. This channel setting, allowing the use of the simplest receiver scheme, seems to be worthless, making reliable communication at any rate impossible. We prove, by adopting statistical mechanics notion, that in the large-system limit such a complexity-constrained CDMA channel gives rise to a non-trivial Shannon-theoretic capacity, rigorously analyzed and corroborated using finite-size channel simulations.Comment: To appear in IEEE Communications Letter

Acquisition, Maintenance and Generalization of Script Training: A Comparison of Errorful and Error-Reducing Conditions

Relatively few studies have investigated errorless versus errorful learning in aphasia, and most have focused on the single word level. In a review of a series of anomia studies, Fillingham et al. (2003) found that rate of success was equivalent for errorless and errorful conditions; the number of therapies using errorful techniques outweighed those based on errorless learning; errorless approaches were likely to achieve positive immediate effects, but many of the errorless studies did not report long term effects and generalization; and there was a lack of studies reporting a direct comparison of errorful and errorless learning. More recent work has continued to support the findings that there is no essential difference between error-free and errorless learning approaches (Middleton & Schwartz, 2012). However, none have investigated and contrasted the errorless/errorful learning paradigm in the production of phrases and sentences. This pilot study directly measures and compare the acquisition, maintenance and generalization of script-training under both error-reducing and errorful conditions. We hypothesized that error-reducing training would improve acquisition of a trained script while errorful learning would improve maintenance of the trained script and generalization to untrained scripts

A method for static and dynamic load analysis of standard and modified spur gears

The mesh stiffness and dynamic load characteristics for several cases of the Normal Contract Ratio and High Contact ratio gearing. The considered contact ratios were grouped in the general range of 1.7,2.0, and 2.3. The HCR gearing is defined by contact ratios equal to or greater than 2.0. The HCR gearing is represented by a group of small pressure angle, fine pitch, and long addendum gearing