Motor preparation of spatially and temporally defined movements: Evidence from startle

This article is available open access through the publisher’s website at the link below. Copyright © 2011 the American Physiological Society.Previous research has shown that the preparation of a spatially targeted movement performed at maximal speed is different from that of a temporally constrained movement (Gottlieb et al. 1989b). In the current study, we directly examined preparation differences in temporally vs. spatially defined movements through the use of a startling stimulus and manipulation of the task goals. Participants performed arm extension movements to one of three spatial targets (20°, 40°, 60°) and an arm extension movement of 20° at three movement speeds (slow, moderate, fast). All movements were performed in a blocked, simple reaction time paradigm, with trials involving a startling stimulus (124 dB) interspersed randomly with control trials. As predicted, spatial movements were modulated by agonist duration and timed movements were modulated by agonist rise time. The startling stimulus triggered all movements at short latencies with a compression of the kinematic and electromyogram (EMG) profile such that they were performed faster than control trials. However, temporally constrained movements showed a differential effect of movement compression on startle trials such that the slowest movement showed the greatest temporal compression. The startling stimulus also decreased the relative timing between EMG bursts more for the 20° movement when it was defined by a temporal rather than spatial goal, which we attributed to the disruption of an internal timekeeper for the timed movements. These results confirm that temporally defined movements were prepared in a different manner from spatially defined movements and provide new information pertaining to these preparation differences

Manipulations to the Timing and Type of Instructions to Examine Motor Skill Performance Under Pressure

There is evidence that prescriptive versus discovery methods of learning can lead to breakdowns under pressure due to “reinvestment” of knowledge and a more conscious, controlled mode of control. There is some speculation that this breakdown is mediated by the attentional focus of the instructions. We expected these effects to also be moderated by when in practice these instructions are given. Across two experiments, five groups practiced a forehand disk throwing task and we manipulated the timing and attentional focus of instructions. Internally directed instructions provided to participants early in practice resulted in a slower rate of acquisition (outcome error) and detrimental effects under stress, in comparison to the same instructions provided later in practice or not at all. Externally directed, technical instructions positively impacted rate of acquisition and regardless of when in practice they were provided, there were no adverse effects associated with instructions under pressure. These results show that the direction of attention encouraged by instructions moderates performance under stress as does the timing of presentation of these instructions

Manipulating target size influences perceptions of success when learning a dart-throwing skill but does not impact retention

Positive feedback or experiences of success during skill acquisition have been shown to benefit motor skill learning. In this study, our aim was to manipulate learners’ success perceptions through a minor adjustment to goal criterion (target size) in a dart-throwing task. Two groups of novice participants practiced throwing at a large (easy) or a small (difficult) target from the same distance. In reference to the origin/centre of the target, the practice targets were alike in objective difficulty and indeed participants in both groups were not different in their objective practice performance (i.e. radial error from the centre). Although the groups experienced markedly different success rates, with the large target group experiencing more hits and reporting greater confidence (or self-efficacy) than the small target group, these practice effects were not carried into longer-term retention, which was assessed after a one-week delay. For success perceptions to moderate or benefit motor learning, we argue that unambiguous indicators of positive performance are necessary, especially for tasks where intrinsic feedback about objective error is salient

A scoping review on developmental activities of girls' and women's sports

We provide a scoping review of research on athlete development in girls' and women's sports. Our emphasis is on pathways to expertise in the context of deliberate practice theory and associated models, such as the Developmental Model of Sport Participation (DMSP). Despite rationale for sex and gender differences in sport development, there are relatively few studies where the developmental pathways of female elite athletes have been evaluated. We sought to map the scope of the literature on this population over the last 30 years, focusing on measures of practice types and amounts. Following an extensive search of the literature, 32 studies were identified that included all female participants or presented sex/gender disaggregated data. Retrospective methods were commonly used to quantify practice, play and specialization. National-level athletes were the most represented, although there was considerable heterogeneity in sport and expertise-level, making general or comparative judgements challenging. We identified some groups that had accumulated high volumes of practice at a young age, particularly in soccer and gymnastics. Across sports and studies, early majority hours of engagement in the primary sport was the norm. Athletes deviated from predictions in the specialization pathway detailed in the DMSP, by continuing to participate in other sports throughout childhood and adolescence. In addition to highlighting the relative paucity of data pertaining to athlete development pathways in female athletes, we show that the data from these groups deviate from predictions detailed in current models of athlete development

The relationship between pitch discrimination and acoustic voice measures in a cohort of female speakers

Background. Evidence across a range of musically trained, hearing disordered and voice disordered populations present conflicting results regarding the relationship between pitch discrimination (PD) and voice quality. PD characteristics of female speakers with and without a musical training background and no selfreported voice disorder, and the relationship between PD and voice quality in this particular population, have not been investigated. Aims. To evaluate PD characteristics in a cohort of female participants without a self-reported voice disorder and the relationship between PD and acoustic voice measures. Method. One hundred fourteen female participants were studied, all of whom self-reported as being non-voice disordered. All completed the Newcastle Assessment of Pitch Discrimination which involved a two-tone PD task. Their voices were recorded producing standardized vocal tasks. Voice samples were acoustically analyzed for frequency-domain measures (fundamental frequency and its standard deviation, and harmonics-to-noise ratio) and spectral-domain measures (cepstral peak prominence and the Cepstral/Spectral Index of Dysphonia). Data were analyzed for the whole cohort and for musical and non-musical training backgrounds. Results. In the whole cohort, there were no significant correlations between PD and acoustic voice measures. PD accuracy in musically trained speakers was better than in non-trained speakers and correlated with fundamental frequency standard deviation in prolonged vowel tasks. Vocalists demonstrated superior PD accuracy and fundamental frequency standard deviation in prolonged vowels compared to instrumentalists but did not show significant correlations between PD and acoustic measures. The Newcastle Assessment of Pitch Discrimination was a reliable tool, showing moderate-good prediction value in differentiating musical background. Conclusions. There was little evidence of a relationship between PD and acoustic measures of voice quality, regardless of musical training background and superior PD accuracy among the musically trained. These data do not support ideas concerning the co-development of perception and action among individuals identified as having voice quality measures within normal ranges. Numerous measures of voice quality, including measures sensitive to pitch, did not distinguish across musically and non-musically trained individuals, despite individual differences in pitch discrimination

Tailoring iridium luminescence and gold nanoparticle size for imaging of microvascular blood flow

Aim: Imaging of blood flow in narrow channels and close to vessel walls is important in cardiovascular research for understanding pathogenesis. Our aim was to provide novel nanoprobes with visible emission and long lifetimes as trackers of flow. Materials & methods: Gold nanoparticles coated with an iridium complex were prepared. Luminescence imaging was used to monitor their flows in different hematocrit blood and in murine tissues. Results: The velocities are independent of hematocrit level and the nanoparticles entering blood circulation can be clearly detected in vessels in lungs, mesentery and the skeletal muscle. Conclusion: The work introduces for the first time iridium-based yellow-green luminescence with nanoparticle size of 100 nm for visualizing and monitoring flows with much higher resolution than conventional alternatives

Synthesis, characterisation and photochemistry of PtIV pyridyl azido acetato complexes

PtII azido complexes [Pt(bpy)(N3)2] (1), [Pt(phen)(N3)2] (2) and trans-[Pt(N3)2(py)2] (3) incorporating the bidentate diimine ligands 2,2′-bipyridine (bpy), 1,10-phenanthroline (phen) or the monodentate pyridine (py) respectively, have been synthesised from their chlorido precursors and characterised by X-ray crystallography; complex 3 shows significant deviation from square-planar geometry (N3–Pt–N3 angle 146.7°) as a result of steric congestion at the Pt centre. The novel PtIV complexes trans, cis-[Pt(bpy)(OAc)2(N3)2] (4), trans, cis-[Pt(phen)(OAc)2(N3)2] (5), trans, trans, trans-[Pt(OAc)2(N3)2(py)2] (6), were obtained from 1–3via oxidation with H2O2 in acetic acid followed by reaction of the intermediate with acetic anhydride. Complexes 4–6 exhibit interesting structural and photochemical properties that were studied by X-ray, NMR and UV-vis spectroscopy and TD-DFT (time-dependent density functional theory). These PtIV complexes exhibit greater absorption at longer wavelengths (ε = 9756 M−1 cm−1 at 315 nm for 4; ε = 796 M−1 cm−1 at 352 nm for 5; ε = 16900 M−1 cm−1 at 307 nm for 6, in aqueous solution) than previously reported PtIV azide complexes, due to the presence of aromatic amines, and 4–6 undergo photoactivation with both UVA (365 nm) and visible green light (514 nm). The UV-vis spectra of complexes 4–6 were calculated using TD-DFT; the nature of the transitions contributing to the UV-vis bands provide insight into the mechanism of production of the observed photoproducts. The UV-vis spectra of 1–3 were also simulated by computational methods and comparison between PtII and PtIV electronic and structural properties allowed further elucidation of the photochemistry of 4–6

Ampullary cancers harbor ELF3 tumor suppressor gene mutations and exhibit frequent WNT dysregulation

The ampulla of Vater is a complex cellular environment from which adenocarcinomas arise to form a group of histopathologically heterogenous tumors. To evaluate the molecular features of these tumors, 98 ampullary adenocarcinomas were evaluated and compared to 44 distal bile duct and 18 duodenal adenocarcinomas. Genomic analyses revealed mutations in the WNT signaling pathway among half of the patients and in all three adenocarcinomas irrespective of their origin and histological morphology. These tumors were characterized by a high frequency of inactivating mutations of ELF3, a high rate of microsatellite instability, and common focal deletions and amplifications, suggesting common attributes in the molecular pathogenesis are at play in these tumors. The high frequency of WNT pathway activating mutation, coupled with small-molecule inhibitors of β-catenin in clinical trials, suggests future treatment decisions for these patients may be guided by genomic analysis

Investigating the influence of music tempo on arousal and behaviour in laboratory virtual roulette

A number of studies indicate that fast music influences performance in everyday activities including shopping and gambling, but the mechanisms through which this effect is realised are not well understood. This study investigates whether fast tempo music influences gambling via an effect on arousal using a laboratory virtual roulette task. One hundred and forty-four participants played virtual roulette whilst listening to fast tempo, slow tempo or no music. Music tempo alone did not influence betting speed, expenditure or risk-taking. Furthermore tempo did not influence participants’ physiological or subjective arousal levels, nor participants’ opinions of the musical stimuli in terms of liking, familiarity, fit or its ability to aid concentration. Our findings suggest that there are some circumstances under which the effect of music tempo does not operate and therefore provides an insight into the limits of music tempo as an explanation for music effects on behaviour. This study has implications for the way that musical characteristics are operationalised in future research into music’s effects on behaviour

Watch and Learn: Seeing Is Better than Doing when Acquiring Consecutive Motor Tasks

During motor adaptation learning, consecutive physical practice of two different tasks compromises the retention of the first. However, there is evidence that observational practice, while still effectively aiding acquisition, will not lead to interference and hence prove to be a better practice method. Observers and Actors practised in a clockwise (Task A) followed by a counterclockwise (Task B) visually rotated environment, and retention was immediately assessed. An Observe-all and Act-all group were compared to two groups who both physically practised Task A, but then only observed (ObsB) or did not see or practice Task B (NoB). The two observer groups and the NoB control group better retained Task A than Actors, although importantly only the observer groups learnt Task B. RT data and explicit awareness of the rotation suggested that the observers had acquired their respective tasks in a more strategic manner than Actor and Control groups. We conclude that observational practice benefits learning of multiple tasks more than physical practice due to the lack of updating of implicit, internal models for aiming in the former