Delayed inhibition of an anticipatory action during motion extrapolation

Background: Continuous visual information is important for movement initiation in a variety of motor tasks. However, even in the absence of visual information people are able to initiate their responses by using motion extrapolation processes. Initiation of actions based on these cognitive processes, however, can demand more attentional resources than that required in situations in which visual information is uninterrupted. In the experiment reported we sought to determine whether the absence of visual information would affect the latency to inhibit an anticipatory action. Methods: The participants performed an anticipatory timing task where they were instructed to move in synchrony with the arrival of a moving object at a determined contact point. On 50% of the trials, a stop sign appeared on the screen and it served as a signal for the participants to halt their movements. They performed the anticipatory task under two different viewing conditions: Full-View (uninterrupted) and Occluded-View (occlusion of the last 500 ms prior to the arrival at the contact point). Results: The results indicated that the absence of visual information prolonged the latency to suppress the anticipatory movement. Conclusion: We suggest that the absence of visual information requires additional cortical processing that creates competing demand for neural resources. Reduced neural resources potentially causes increased reaction time to the inhibitory input or increased time estimation variability, which in combination would account for prolonged latency

Variable practice: is this the best option for motor skill acquisition?

O objetivo desta pesquisa foi verificar o efeito do tipo de prática na aquisição do saque do tênis de mesa. Quinze sujeitos com idades entre 11 e 15 anos foram designados, através de sorteio, para três grupos de prática: constante (GC), variado (GV) e misto (GM). A tarefa consistiu em acertar o centro de um alvo com uma bola, utilizando-se do saque de “forehand” do tênis de mesa. Os sujeitos realizaram 240 tentativas na fase de aquisição e 24 tentativas na fase de transferência. Na fase de aquisição, o GC realizou todas as tentativas em um único alvo (P3), o GV realizou as tentativas nos três alvos (PI, P2 e P3), seqüenciados aleatoriamente, e o GM realizou a primeira metade das tentativas na mesma condição do GC e a outra metade na mesma condição de prática de GV. Na fase de transferência, todos os sujeitos realizaram as tentativas em dois novos alvos (TI e T2). O teste de Friedman, com nível de significância de 0,05, revelou diferenças intragrupos na fase de aquisição, mas o teste de Kruskal-Wallis não revelou diferenças intergrupos na fase de transferência. Os resultados, portanto, não mostram um efeito claro do tipo de prática, entretanto foi verificada uma tendência favorável à prática constanteThe purpose of the present study was to verify the effect of practice schedule in the acquisition C* of the table tennis service. Fifteen subjects aged between 11 and 15 years were assigned, at random, to three practice groups: constant (CG), varied (VG) and mixed (MG). The task consisted in hitting the center of one target with a ball, using a forehand table tennis service. The subjects performed 240 trials in the acquisition phase and 24 trials in the transfer phase. In the acquisition phase, the CG performed all trials on one target (P3), the VG performed trials on three targets (PI, P2 and P3), in a random sequence, and the MG performed the first half of the trials in the same condition of CG and the other half in the same practice condition of the VG. In the transfer phase, all subjects performed the trials on two new targets (T1 and T2). The Friedman test with significance level of 0.05 revealed within groups differences in the acquisition phase, but the KruskalWallis test did not reveal any difference between groups in the transfer phase. Therefore, the results did not show a clear effect of practice schedule, however, a positive tendency towards constant practice was verifie

Electric and acoustic stimulation during movement preparation can facilitate movement execution in healthy participants and stroke survivors

There has been increasing interest in the use of loud acoustic stimulation (LAS) to gain insight into the preparation and initiation of motor actions. Typically, LAS presented during movement preparation in healthy participants culminates in the earlier than normal initiation of the prepared movement and an increase in the magnitude of the response. Recent reports have shown LAS can also facilitate movement in chronic stroke survivors. This suggests that current therapies for motor recovery after stroke might benefit from employing such alternate methods of triggering movement. In this study we sought to test a new way to facilitate motor actions that could be of relevance in clinical settings. Five individuals with chronic motor impairments due to stroke and eight healthy young adults performed a functional reaching task in response to a visual go-signal. On 30% of the trials, LAS or electric stimuli (collectively, sensory stimuli) were unexpectedly presented in synchrony with the go-signal. Both healthy and stroke participants reacted with shorter latencies and executed faster responses when sensory stimulation was synchronized with the go-signal. We have replicated previous findings showing acoustic stimuli can aid movement execution in chronic stroke survivors and demonstrated the same type of effect can be achieved using electric stimulation. Thus, these two types of sensory stimuli can be easily integrated with current devices available to assist people with stroke to engage in rehabilitation efforts

Do We Know What We Need? Preference for Feedback About Accurate Performances Does Not Benefit Sensorimotor Learning

Previous research on skill acquisition has shown that learners seem to prefer receiving knowledge of results (KR) about those trials in which they have performed more accurately. In the present study, we assessed whether this preference leads to an advantage in terms of skill acquisition, transfer, and retention of their capacity to extrapolate the motion of decelerating objects during periods of visual occlusion. Instead of questionnaires, we adopted a more direct approach to investigate learners' preferences for KR. Participants performed 90 trials of a motion extrapolation task (acquisition phase) in which, every three trials, they could decide between receiving KR about their best or worst performance. Retention and transfer tests were carried out 24 hr after the acquisition phase, without KR, to examine the effects of the self-selected KR on sensorimotor learning. Consistent with the current literature, a preference for receiving KR about the most accurate performance was observed. However, participants' preferences were not consistent throughout the experiment as less than 10% (N = 40) selected the same type of KR in all their choices. Importantly, although preferred by most participants, KR about accurate performances had detrimental effects on skill acquisition, suggesting that learners may not always choose the KR that will maximize their learning experiences and skill retention

Preliminary evaluation of the friends for life program on students' and teachers' emotional states for a school in a low socio-economic status area

The purpose of this study was to examine the impact of the FRIENDS for Life program on students' and teachers' emotional outcomes in a school serving a high-poverty population. The focus of the intervention was to train/coach teachers with strategies to develop social and emotional skills for students. A single group, pre/post-test design was used to conduct a preliminary investigation of the intervention to improve participants' social and emotional outcomes. At the end of the intervention, students who were at risk showed significant decrease in their anxiety levels and teacher's demonstrated significant improvements on their emotional resilience

Triggering Mechanisms for Motor Actions: The Effects of Expectation on Reaction Times to Intense Acoustic Stimuli

Motor actions can be released much sooner than normal when the go-signal is of very high intensity (>100 dBa). Although statistical evidence from individual studies has been mixed, it has been assumed that sternocleidomastoid (SCM) muscle activity could be used to distinguish between two neural circuits involved in movement triggering. We summarized meta-analytically the available evidence for this hypothesis, comparing the difference in premotor reaction time (RT) of actions where SCM activity was elicited (SCM+ trials) by loud acoustic stimuli against trials in which it was absent (SCM- trials). We found ten studies, all reporting comparisons between SCM+ and SCM- trials. Our mini meta-analysis showed that premotor RTs are faster in SCM+ than in SCM- trials, but the effect can be confounded by the variability of the foreperiods employed. We present experimental data showing that foreperiod predictability can induce differences in RT that would be of similar size to those attributed to the activation of different neurophysiological pathways to trigger prepared actions. We discuss plausible physiological mechanisms that would explain differences in premotor RTs between SCM+ and SCM- trials

It Pays to Prepare: Human Motor Preparation Depends on the Relative Value of Potential Response Options

Alternative motor responses can be prepared in parallel. Here, we used electroencephalography (EEG) to test whether the parallel preparation of alternative response options is modulated by their relative value. Participants performed a choice response task with three potential actions: isometric contraction of the left, the right, or both wrists. An imperative stimulus (IS) appeared after a warning cue, such that the initiation time of a required action was predictable, but the specific action was not. To encourage advanced preparation, the target was presented 200 ms prior to the IS, and only correct responses initiated within ±100 ms of the IS were rewarded. At baseline, all targets were equally rewarded and probable. Then, responses with one hand were made more valuable, either by increasing the probability that the left or right target would be required (Exp. 1; n = 31) or by increasing the reward magnitude of one target (Exp. 2, n = 36). We measured reaction times, movement vigor, and an EEG correlate of action preparation (value-based lateralized readiness potential) prior to target presentation. Participants responded earlier to more frequent and more highly rewarded targets, and movements to highly rewarded targets were more vigorous. The EEG was more negative over the hemisphere contralateral to the more repeated/rewarded hand, implying an increased neural preparation of more valuable actions. Thus, changing the value of alternative response options can lead to greater preparation of actions associated with more valuable outcomes. This preparation asymmetry likely contributes to behavioral biases that are typically observed toward repeated or rewarded targets

Visual attention affects temporal estimation in anticipatory motor actions

The production of accurate motor actions requires successful extraction of relevant information about the target of that action. By the same token, it also requires the successful exclusion of potentially distracting, irrelevant information. This study sought to determine the impact of transient visual distractions on performance in an anticipatory timing task, in particular the temporal and spatial relationship between distractor and target at which maximal distraction occurs. The results support the notion of a critical temporal and spatial window of distraction which provides insight into the visuomotor processes underlying distraction