Online corrections can occur within movement imagery: An investigation of the motor-cognitive model.

The motor-cognitive model proposes that movement imagery additionally requires conscious monitoring owing to an absence of veridical online sensory feedback. Therefore, it is predicted that there would be a comparatively limited ability for individuals to update or correct movement imagery as they could within execution. To investigate, participants executed and imagined target-directed aiming movements featuring either an unexpected target perturbation (Exp. 1) or removal of visual sensory feedback (Exp. 2). The results of both experiments indicated that the time-course of executed and imagined movements was equally influenced by each of these online visual manipulations. Thus, contrary to some of the tenets of the motor-cognitive model, movement imagery holds the capacity to interpolate online corrections despite the absence of veridical sensory feedback. The further theoretical implications of these findings are discussed.

Theoretical explanations and the availability of information for learning via combined action observation and motor imagery: a commentary on Eaves et al. (2022).

The recent review by Eaves et al. (Psychological Research/Psychologische Forschung, 2022) outlines the research conducted to-date on combined action-observation and motor imagery (AOMI), and more specifically, its added benefit to learning. Of interest, these findings have been primarily attributed to the dual action simulation hypothesis, whereby AO and MI activate separable representations for action that may be later merged when they are congruent with one another. The present commentary more closely evaluates this explanation. What's more, we offer an alternative information-based argument where the benefit to learning may be served instead by the availability of key information. Along these lines, we speculate on possible future directions including the need for a transfer design.

Medium chain triglycerides with a C8:C10 ratio of 30:70 enhances cognitive performance and mitigates the cognitive decline associated with prolonged exercise in young and healthy adults.

INTRODUCTION: Prolonged exercise has been linked to a decline in cognitive function due to a variety of factors, such as a drop in oxygen in the prefrontal cortex and an increase in stress hormones and neurotransmitters. Medium chain triglycerides (MCTs) may possibly offset this decline as they provide energy for the brain via both direct and indirect pathways, alongside promoting chronic physiological adaptations within the brain. METHODS: Participants were divided into two groups; MCT (n = 9) and Placebo (n = 10). The MCT gels contained 6 g of MCT with a C8:C10 ratio of 30:70, whereas the placebo gels contained carbohydrates of similar calorific value to the MCT gels. Participants visited the laboratory on three occasions (familiarisation/fitness test, pre-supplementation, post-supplementation), during which they performed a battery of cognitive tasks assessing domains such as processing speed, working memory, selective attention, decision making and coordination, before and after a prolonged bout of exercise (60 mins at 90% gas exchange threshold (GET). A 2-week supplementation period between visits 2 and 3 involved the ingestion of 2 gels per day. RESULTS: Exercise resulted in detriments in most cognitive tasks pre-supplementation for both groups, and post-supplementation for the Placebo group (main effect ps< 0.05). Post-supplementation, the effect of exercise was mediated in the MCT group for all cognitive tasks (main effect ps< 0.05), except for the Digit and Spatial Span Backwards test phases (main effect ps> 0.05). Furthermore, MCT supplementation enhanced before-exercise cognitive performance and in some measures, such as working memory, this was maintained after-exercise (interaction effect ps> 0.05). CONCLUSIONS: Chronic MCT supplementation enhanced before-exercise cognitive performance and offset the cognitive decline caused by a prolonged bout of exercise. In some cases, improvements in before-exercise cognitive performance were maintained after-exercise.

Enhanced expectancies benefit performance under distraction, but compromise it under stress: Exploring the OPTIMAL theory.

Motor learning can benefit from practice under enhanced expectancies; that is, the belief one can generate an intended positive outcome. According to the OPTIMAL (Optimizing Performance Through Intrinsic Motivation and Attention for Learning) theory, this benefit manifests from a greater coupling between action and its external consequences, which potentially coincides with a more automatic mode of control. The aim of the study was to examine this possibility, and in so doing, understand more about the psycho-motor processes underpinning the influence of expectancies. On Day 1, novice participants practiced a dart-throwing task under enhanced (EE) (n = 11), reduced (RE) (n = 12) or no (control; CTL) (n = 12) expectancies. Enhanced and reduced expectancies were indirectly manipulated by positively reinforcing shots that landed within the large or small circle on the dartboard, respectively. On Day 2, participants transferred to a dual-task (i.e., tone-counting) or stress (i.e., social-comparative threat, false feedback) setting. While there was no evidence of improvement across practice, RE was significantly worse than CTL for the dual-task, but EE was significantly worse than RE and CTL under stress (ps < 0.05). Therefore, the ability of EE to retain performance within the dual-task, but decline under stress, suggests a more automatic mode of control was adopted. Both theoretical and practical implications are discussed.

Dissociating the Influence of Perceptual Biases and Contextual Artifacts Within Target Configurations During the Planning and Control of Visually Guided Action.

The failure of perceptual illusions to elicit corresponding biases within movement supports the view of two visual pathways separately contributing to perception and action. However, several alternative findings may contest this overarching framework. The present study aimed to examine the influence of perceptual illusions within the planning and control of aiming. To achieve this, we manipulated and measured the planning/control phases by respectively perturbing the target illusion (relative size-contrast illusion; Ebbinghaus/Titchener circles) following movement onset and detecting the spatiotemporal characteristics of the movement trajectory. The perceptual bias that was indicated by the perceived target size estimates failed to correspondingly manifest within the effective target size. While movement time (specifically, time after peak velocity) was affected by the target configuration, this outcome was not consistent with the direction of the perceptual illusions. These findings advocate an influence of the surrounding contextual information (e.g., annuli) on movement control that is independent of the direction predicted by the illusion.

The effects of medium chain triglyceride (MCT) supplementation using a C8:C10 ratio of 30:70 on cognitive performance in healthy young adults.

PURPOSE: The brain can utilise medium chain triglycerides (MCTs) as an alternative fuel to glucose, and research has shown that MCT ingestion improves cognitive function in diseased and/or elderly individuals. The aim of this study is to determine if these improvements can also be observed in young, healthy adults. Furthermore, we aim to establish the ideal dosage and timeframe necessary for an effect. METHODS: Participants were divided equally into three groups of 10 (Placebo (0 g), 12 g and 18 g MCT/day) and were supplemented for 4 weeks. The supplement had a C8:C10 ratio of 30:70. Participants visited the laboratory once a week for 5 weeks (baseline, test weeks 1-4) to undergo a battery of cognitive tests; Trail Making, Digit Span, Spatial Span, Covert Shift of Attention, and Rapid Visual Information Processing. RESULTS: After 2-3 weeks of supplementation, MCT ingestion enhanced performance in cognitive tasks, including: Trail Making A/B and Digit Span Forwards/Backwards (ps<0.001) when compared to a placebo group taking a carbohydrate gel. In Spatial Span Backwards, there was a significant main effect of group (p = 0.002). Where significance was seen, there were main effects of time after 2-3 weeks (ps<0.05). There was minimal difference between the two MCT intervention groups in most measures (ps>0.05). There were also null results in tasks measuring attention and reaction time (ps>0.05). CONCLUSIONS: MCT ingestion improved cognitive performance after 2-3 weeks, with minimal difference between taking 12 g and 18 g MCT/day groups, suggesting a possible dose-response threshold at 12 g MCT/day when supplementing over a short period.

Examining the equivalence between imagery and execution within the spatial domain - Does motor imagery account for signal-dependent noise?

Motor imagery is suggested to be functionally equivalent to physical execution as they each utilise a common neural representation. The present study examined whether motor imagery correspondingly reflects the spatial characteristics of physically executed movements, including the signal-dependent noise that typically manifests in more variable end locations (as indicated by effective target width; We). Participants executed or imagined a single, upper-limb target-directed aim in the horizontal medio-lateral direction. The start and end of the imagined movements were indexed by the lifting and lowering of the limb over the home position, respectively. Following each imagined movement, participants had to additionally estimate their imagined end location relative to the target. All the movements had to be completed at a pre-specified criterion time (400 ms, 600 ms, 800 ms). The results indicated that the We increased following a decrease in movement time for execution, but not imagery. Moreover, the total error of imagined movements was greater than the actual error of executed movements. While motor imagery may comprise a neural representation that also contributes to the execution of movements, it is unable to closely reflect the random sources of variability. This limitation of motor imagery may be attributed to the comparatively limited efferent motor signals.

Using PETTLEP imagery as a simulation technique in nursing: Research and guidelines.

One of the most valuable skill sets developed in nurse education is the ability to develop the clinical and practical skills learned. This can take various forms such as university-based practice, simulation and direct experience with patients. To this end imagery, a process where all of the senses are used to create or recreate an experience in the mind, could represent simulated practice of clinical skills. Research on imagery has indicated that the technique, when used to assist in the performance of skill based procedures carried out by nurses can be beneficial. However, guidelines are lacking in this area of simulated practice. In this article, we review current research on the topic of imagery in enhancing skilled performance and outline a model that can assist in conducting interventions. Furthermore, we consider how this could be implemented within a nursing environment to produce beneficial performance effects in both pre-registration and registered nurses.

The effect of action observation and motor imagery combinations on upper limb kinematics and EMG during dart-throwing.

Recent research has begun to employ interventions that combine action observation and motor imagery (AOMI) with positive results. However, little is known about the underpinning facilitative effect on performance. Participants (n = 50) were randomly allocated to one of five training groups: action observation (AO), motor imagery (MI), simultaneous action observation and motor imagery (S-AOMI), alternate action observation and motor imagery (A-AOMI), and control. The task involved dart-throwing at a concentric circle dartboard at pre- and post-test. Interventions were conducted 3 times per week for 6 weeks. Data were collected from performance outcomes and mean muscle activation of the upper and forearm muscles. Angular velocity and peak angular velocity measurements of the elbow were also collected from the throwing arm. Results showed performance of the A-AOMI group improved to a significantly greater degree than the AO (P = .04), MI (P = .04), and control group (P = .02), and the S-AOMI group improved to a greater degree than the control group (P = .02). Mean muscle activation of the triceps brachii significantly reduced in the S-AOMI and A-AOMI (P < .01) groups, and participants in the AO (P = .04), A-AOMI, and S-AOMI (P < .01) groups significantly reduced activation in the bicep brachii from pre- to post-test. Peak angular velocity significantly decreased from pre- to post-test in both A-AOMI and S-AOMI (P < .01) groups. The results reaffirm the benefits of AOMI for facilitating skill learning and provide an insight how these interventions produce favorable changes in EMG and movement kinematics.

Examining the equivalence between imagery and execution - Do imagined and executed movements code relative environmental features?

Imagined actions engage some of the same neural substrates and related sensorimotor codes as executed actions. The equivalency between imagined and executed actions has been frequently demonstrated by the mental and physical chronometry of movements; namely, the imagination and execution of aiming movements in a Fitts paradigm. The present study aimed to examine the nature or extent of this equivalence, and more specifically, whether imagined movements encompass the relative environmental features as do executed movements. In two separate studies, participants completed a series of imagined or executed reciprocal aiming movements between standard control targets (no annuli), perceptually small targets (large annuli) and perceptually large targets (small annuli) (Ebbinghaus illusions). The findings of both studies replicated the standard positive relation between movement time and index of difficulty for imagined and executed movements. Furthermore, movement times were longer for targets with surrounding annuli compared to the movement times without the annuli suggesting a general interference effect. Hence, the surrounding annuli caused a longer time, independent of the illusory target size, most likely to avoid a potential collision and more precisely locate the endpoint. Most importantly, this feature could not be discriminated as a function of the task (imagined vs. executed). These findings lend support to the view of a common domain for imagined and executed actions, while elaborating on the precision of their equivalence.