Motor Processes Research Articles

Étiopathogénie des troubles neurologiques fonctionnels : marqueurs biologiques et modèles théoriques

ObjectivesFunctional neurological disorders have witnessed intense research activity in the fields of structural and functional neuroimaging for more than twenty years. Thus, we propose a synthesis of recent research findings and etiological hypotheses that have been proposed so far. This work should help clinicians to better understand the nature of the mechanisms involved, but also help patients to increase their knowledge about the biological features underlying their functional symptoms. MethodsWe carried out a narrative review of international publications dealing with neuroimaging and biology of functional neurological disorders, from 1997 to 2023. ResultsSeveral brain networks underlie functional neurological symptoms. These networks play a role in the management of cognitive resources, in attentional control, emotion regulation, in agency and in the processing of interoceptive signals. The mechanisms of the stress response are also associated with the symptoms. The biopsychosocial model helps to better understand predisposing, precipitating, and perpetuating factors involved. The functional neurological phenotype results from the interaction between: i) a specific pre-existing vulnerability resulting from biological background and epigenetic modifications, and ii) exposure to stress factors, according to the stress-diathesis model. This interaction causes emotional disturbances including hypervigilance, lack of integration of sensations and affects, and emotional dysregulation. These characteristics in turn impact the cognitive, motor and affective control processes related with the functional neurological symptoms. ConclusionsA better knowledge of the biopsychosocial determinants of brain network dysfunctions is necessary. Understanding them would help developing targeted treatments, but is also critical for patients care.

An eye for detail: Eye movements and attention at the foveal scale

Human vision relies on a tiny region of the retina, the 1-deg foveola, to achieve high spatial resolution. Foveal vision is of paramount importance in daily activities, yet its study is challenging, as eye movements incessantly displace stimuli across this region. Here I will review work that, building on recent advances in eye-tracking and gaze-contingent display, examines how attention and eye movements operate at the foveal level. This research highlights how exploration of fine spatial detail unfolds following visuomotor strategies reminiscent of those occurring at larger scales. It shows that, together with highly precise control of attention, this motor activity is linked to non–homogenous processing within the foveola and selectively modulates sensitivity both in space and time. Overall, the picture emerges of a highly dynamic foveal perception in which fine spatial vision, rather than simply being the result of placing a stimulus at the center of gaze, is the result of a finely tuned and orchestrated synergy of motor, cognitive, and attentional processes.

The nonlinearity of pupil diameter fluctuations in an insight task as criteria for detecting children who solve the problem from those who do not.

Insights, characterized by sudden discoveries following unsuccessful problem-solving attempts, are fascinating phenomena. Dynamic systems perspectives argue that insight arises from self-organizing perceptual and motor processes. Entropy and fractal scaling are potential markers for emerging new and effective solutions. This study investigated whether specific features associated with self-organization in dynamical systems can distinguish between individuals who succeed and those who fail in solving insight tasks. To achieve this, we analyzed pupillary diameter fluctuations of children aged 6 to 12 during the 8-coin task, a well-established insight task. The participants were divided into two groups: successful (n = 24) and unsuccessful (n = 43) task completion. Entropy, determinism, recurrence ratio, and the β scaling exponent were estimated using Recurrence Quantification and Power Spectrum Density analyses. The results indicated that the solver group exhibited more significant uncertainty and lower predictability in pupillary diameter fluctuations before finding the solution. Recurrence Quantification Analysis revealed changes that went unnoticed by mean and standard deviation measures. However, the β scaling exponent did not differentiate between the two groups. These findings suggest that entropy and determinism in pupillary diameter fluctuations can identify early differences in problem-solving success. Further research is needed to determine the exclusive role of perceptual and motor activity in generating insights and investigate these results' generalizability to other tasks and populations.

Cued motor processing in autism and typical development: A high-density electrical mapping study of response-locked neural activity in children and adolescents.

Motor atypicalities are common in autism spectrum disorder (ASD) and are often evident prior to classical ASD symptoms. Despite evidence of differences in neural processing during imitation in autistic individuals, research on the integrity and spatiotemporal dynamics of basic motor processing is surprisingly sparse. To address this need, we analysed electroencephalography (EEG) data recorded from a large sample of autistic (n = 84) and neurotypical (n = 84) children and adolescents while they performed an audiovisual speeded reaction time (RT) task. Analyses focused on RTs and response-locked motor-related electrical brain responses over frontoparietal scalp regions: the late Bereitschaftspotential, the motor potential and the reafferent potential. Evaluation of behavioural task performance indicated greater RT variability and lower hit rates in autistic participants compared to typically developing age-matched neurotypical participants. Overall, the data revealed clear motor-related neural responses in ASD, but with subtle differences relative to typically developing participants evident over fronto-central and bilateral parietal scalp sites prior to response onset. Group differences were further parsed as a function of age (6-9, 9-12 and 12-15 years), sensory cue preceding the response (auditory, visual and bi-sensory audiovisual) and RT quartile. Group differences in motor-related processing were most prominent in the youngest group of children (age 6-9), with attenuated cortical responses observed for young autistic participants. Future investigations assessing the integrity of such motor processes in younger children, where larger differences may be present, are warranted.

Perception-Action Integration Is Altered in Functional Movement Disorders.

Although functional neurological movement disorders (FMD) are characterized by motor symptoms, sensory processing has also been shown to be disturbed. However, how the integration of perception and motor processes, essential for the control of goal-directed behavior, is altered in patients with FMD is less clear. A detailed investigation of these processes is crucial to foster a better understanding of the pathophysiology of FMD and can systematically be achieved in the framework of the theory of event coding (TEC). The aim was to investigate perception-action integration processes on a behavioral and neurophysiological level in patients with FMD. A total of 21 patients and 21 controls were investigated with a TEC-related task, including concomitant electroencephalogram (EEG) recording. We focused on EEG correlates established to reflect perception-action integration processes. Temporal decomposition allowed to distinguish between EEG codes reflecting sensory (S-cluster), motor (R-cluster), and integrated sensory-motor processing (C-cluster). We also applied source localization analyses. Behaviorally, patients revealed stronger binding between perception and action, as evidenced by difficulties in reconfiguring previously established stimulus-response associations. Such hyperbinding was paralleled by a modulation of neuronal activity clusters, including reduced C-cluster modulations of the inferior parietal cortex and altered R-cluster modulations in the inferior frontal gyrus. Correlations of these modulations with symptom severity were also evident. Our study shows that FMD is characterized by altered integration of sensory information with motor processes. Relations between clinical severity and both behavioral performance and neurophysiological abnormalities indicate that perception-action integration processes are central and a promising concept for the understanding of FMD. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Neural entrainment underpins sensorimotor synchronization to dynamic rhythmic stimuli

Neural entrainment, defined as unidirectional synchronization of neural oscillations to an external rhythmic stimulus, is a topic of major interest in the field of neuroscience. Despite broad scientific consensus on its existence, on its pivotal role in sensory and motor processes, and on its fundamental definition, empirical research struggles in quantifying it with non-invasive electrophysiology. To this date, broadly adopted state-of-the-art methods still fail to capture the dynamic underlying the phenomenon.Here, we present event-related frequency adjustment (ERFA) as a methodological framework to induce and to measure neural entrainment in human participants, optimized for multivariate EEG datasets. By applying dynamic phase and tempo perturbations to isochronous auditory metronomes during a finger-tapping task, we analyzed adaptive changes in instantaneous frequency of entrained oscillatory components during error correction. Spatial filter design allowed us to untangle, from the multivariate EEG signal, perceptual and sensorimotor oscillatory components attuned to the stimulation frequency.Both components dynamically adjusted their frequency in response to perturbations, tracking the stimulus dynamics by slowing down and speeding up the oscillation over time. Source separation revealed that sensorimotor processing enhanced the entrained response, supporting the notion that the active engagement of the motor system plays a critical role in processing rhythmic stimuli. In the case of phase shift, motor engagement was a necessary condition to observe any response, whereas sustained tempo changes induced frequency adjustment even in the perceptual oscillatory component. Although the magnitude of the perturbations was controlled across positive and negative direction, we observed a general bias in the frequency adjustments towards positive changes, which points at the effect of intrinsic dynamics constraining neural entrainment.We conclude that our findings provide compelling evidence for neural entrainment as mechanism underlying overt sensorimotor synchronization, and highlight that our methodology offers a paradigm and a measure for quantifying its oscillatory dynamics by means of non-invasive electrophysiology, rigorously informed by the fundamental definition of entrainment.

Classifying migraine using PET compressive big data analytics of brain's μ-opioid and D2/D3 dopamine neurotransmission.

Introduction: Migraine is a common and debilitating pain disorder associated with dysfunction of the central nervous system. Advanced magnetic resonance imaging (MRI) studies have reported relevant pathophysiologic states in migraine. However, its molecular mechanistic processes are still poorly understood in vivo. This study examined migraine patients with a novel machine learning (ML) method based on their central μ-opioid and dopamine D2/D3 profiles, the most critical neurotransmitters in the brain for pain perception and its cognitive-motivational interface. Methods: We employed compressive Big Data Analytics (CBDA) to identify migraineurs and healthy controls (HC) in a large positron emission tomography (PET) dataset. 198 PET volumes were obtained from 38 migraineurs and 23 HC during rest and thermal pain challenge. 61 subjects were scanned with the selective μ-opioid receptor (μOR) radiotracer [11C]Carfentanil, and 22 with the selective dopamine D2/D3 receptor (DOR) radiotracer [11C]Raclopride. PET scans were recast into a 1D array of 510,340 voxels with spatial and intensity filtering of non-displaceable binding potential (BPND), representing the receptor availability level. We then performed data reduction and CBDA to power rank the predictive brain voxels. Results: CBDA classified migraineurs from HC with accuracy, sensitivity, and specificity above 90% for whole-brain and region-of-interest (ROI) analyses. The most predictive ROIs for μOR were the insula (anterior), thalamus (pulvinar, medial-dorsal, and ventral lateral/posterior nuclei), and the putamen. The latter, putamen (anterior), was also the most predictive for migraine regarding DOR D2/D3 BPND levels. Discussion: CBDA of endogenous μ-opioid and D2/D3 dopamine dysfunctions in the brain can accurately identify a migraine patient based on their receptor availability across key sensory, motor, and motivational processing regions. Our ML-based findings in the migraineur's brain neurotransmission partly explain the severe impact of migraine suffering and associated neuropsychiatric comorbidities.

Human brain organoid transplantation: ethical implications of enhancing specific cerebral functions in small-animal models

Brain organoids are self-organizing, three-dimensional tissues derived from pluripotent stem cells that recapitulate many aspects of the cellular diversity and architectural features of the developing brain. Recently, there has been growing interest in using human brain organoid transplantation in animal models as a means of addressing the limitations of in vitro culture, such as the lack of vascularization, and to explore the potential of organoids for neural repair. While there has been substantial debate on the ethical implications of brain organoid research, particularly the potential for organoids to exhibit higher-order brain functions such as consciousness, the impact of human organoid grafts on animal hosts has been less extensively discussed. Enhancement of host animal brain function may not be technically feasible at this time, but it is imperative to carefully consider the moral significance of these potential outcomes. Here, we discuss the ethical implications of enhancing somatosensation, motor processes, memory, and basic socialization in small-animal models. We consider the moral implications of such outcomes and if safeguards are needed to accommodate any increased moral status of animals transplanted with human brain organoids.

Comparison of manual dexterity of people with Alzheimer’s disease and cognitively healthy older adults: The impact of cognition

AbstractBackgroundAlzheimer’s disease (AD) not only effects the cognitive level, but also leads to significant decline in motor skill. Manual dexterity emerges with the interaction of cognitive and motor processes and is seen as an important predictor of functional independence. The aim of this study was to compare manual dexterity in people with AD with healthy older adults and to investigate the effect of cognitive level on manual dexterity.MethodThe Nine Hole Peg Test (NHPT) was used for manual dexterity assessment. Cognitive function were assessed with Montreal Cognitive Assessment (MoCA). Statistical analysis was performed by Mann Whitney U Test and regression analysis in SPSS 22.0 package program.ResultTwenty nine people with AD (78.04±6.49, 48.27% female) and ten cognitively healthy older adult (74.8±7.22, 30% female) included study. NHPT results of the dominant hand were 31.87±7.33 sec. and 21.66±2.85 sec.; MoCA scores were 13.79±5.76 and 24.5±2.32, respectively, in the people with AD and cognitively healthy older adults. There was significant difference in NHPT results between groups (p<.001). Significant correlation was found between NHPT and MoCA (p<.001, r = .648). It was found that cognitive level significantly predicted manual dexterity (β = .648, R2 = .42, F [1,27] = 19.58, p<.001).ConclusionManual dexterity in AD shows a significant decrease compared to the cognitively healthy older adults. In our study, it was shown that the decrease in manual dexterity occurs with the effect of cognition at a rate of 42%. Deteriorating manual dexterity with decreased cognition is likely to accelerate patients' withdrawal from activities of daily living. Also, rehabilitation programs that include activities for manual dexterity may slow down the process of participation restriction in AD.

Redefining the decisional components of motor responses: Evidence from lexical and object decision tasks.

Models of decision making focusing on two-alternative choices have classically described motor-response execution as a nondecisional stage that serially follows the termination of decision processes. Recent evidence, however, points toward a more continuous transition between decision and motor processes. We investigated this transition in two lexical decisions and one object decision task. By recording the electromyographic (EMG) signal associated with the muscle responsible for the manual responses (i.e., button press), we partitioned single-trial reaction times into premotor (the time elapsing from stimulus onset until the onset of the EMG burst) and motor times (the time elapsing from the onset of the EMG burst and the button press), with the latter measuring response execution. Responses were slower for pseudowords and pseudo-objects compared to words and real objects. Importantly, these effects were reliable even at the level of motor time measures. Differently, despite the reliable effect at the level of reaction times and premotor times, there was no difference in motor times between high- and low-frequency words. Although these results, in line with recent evidence, challenge a purely noncognitive characterization of motor-response execution, they further suggest that motor times may selectively capture specific decisional components, which we identify with late-occurring verification and/or control mechanisms. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Time-of-day influences resting-state functional cortical connectivity.

Time-of-day is rarely considered during experimental protocols investigating motor behavior and neural activity. The goal of this work was to investigate differences in functional cortical connectivity at rest linked to the time of the day using functional Near-Infrared Spectroscopy (fNIRS). Since resting-state brain is shown to be a succession of cognitive, emotional, perceptual, and motor processes that can be both conscious and nonconscious, we studied self-generated thought with the goal to help in understanding brain dynamics. We used the New-York Cognition Questionnaire (NYC-Q) for retrospective introspection to explore a possible relationship between the ongoing experience and the brain at resting-state to gather information about the overall ongoing experience of subjects. We found differences in resting-state functional connectivity in the inter-hemispheric parietal cortices, which was significantly greater in the morning than in the afternoon, whilst the intra-hemispheric fronto-parietal functional connectivity was significantly greater in the afternoon than in the morning. When we administered the NYC-Q we found that the score of the question 27 ("during RS acquisition my thoughts were like a television program or film") was significantly greater in the afternoon with respect to the morning. High scores in question 27 point to a form of thought based on imagery. It is conceivable to think that the unique relationship found between NYC-Q question 27 and the fronto-parietal functional connectivity might be related to a mental imagery process during resting-state in the afternoon.

Analytical Calculation of Air Gap Magnetic Field of SPMSM with Eccentrically Cut Poles Based on Magnetic Pole Division

In the design process of surface-mounted permanent magnet motor (SPMSM) for industrial robots and computer numerical control (CNC) machine tools, to pursue the sinusoidal nature of the back electromotive force, the magnetic poles in the form of eccentric pole cutting structure are often used. To analyze the no-load air gap magnetic field of the SPMSM with eccentrically cut poles simply and accurately, a subdomain model magnetic field analytical calculation method based on equal-area integral block processing of permanent magnets is proposed. The problem that the traditional subdomain analysis model cannot be directly applied to the SPMSM with eccentrically cut poles of unequal thickness is solved. The proposed method considers the influence of stator slotting and the actual permeability of permanent magnets, and directly obtains the fundamental wave and harmonic components of the no-load air gap flux density by solving the subdomain model. The finite element method (FEM) is used to directly calculate the air gap magnetic field for verification. The results of the analytical method and the no-load air gap magnetic density calculated by the FEM are consistent, which verifies the accuracy of the proposed analytical method and can quickly guide the design of the SPMSM with eccentrically cut poles.

The Relative Strengths of Relationships Between Fine Motor Skills, Working Memory, Processing Speed and Fluid Intelligence in Early Elementary School Children.

The goal in the present paper was to examine the combined and relative impact of fine motor ability, auditory working memory, and processing speed on fluid intelligence in a sample of early elementary school students. Our participant sample was 145 children (Mage = 9.1years, SD = 1.1; 80 boys, 65 girls). We used the Raven's Colored Progressive Matrices Test as a measure of fluid intelligence and five other measures to represent the three predictor variables: the Grooved Pegboard Test as a measure of fine motor skills, Digit Span Forwards and Digit Span Backwards tests as measures of working memory, and Rapid Automatized Naming and Letter-Digit Substitution tasks as measures of processing speed. Regression analyses indicated that only two of these measures had a statistically significant association with the fluid intelligence test scores, namely, scores on the Grooved Pegboard (fine motor skills) and Digit Span Backwards (working memory) tests, with these two measures explaining 35% of the variance in the fluid intelligence test scores. Thus, fine motor skills and working memory were correlated with fluid intelligence in early elementary-grade students. Until the directions of these relationships are better understood, we might assume that interventions aiming to increase young children's fluid intelligence, or at least their intelligence scores, might partly target working memory and fine motor skills.

0403 Functional Connectivity of Brain Networks Predicts Polysomnographically Measured Sleep

Abstract Introduction The arousal hypothesis predicts that increased cognitive and somatic arousal interfere with sleep among patients with insomnia. Evidence suggests that the connectivity of the brain’s default mode network (DMN) may play an important role in this process. Here, we examined the association between whole cortex resting state functional connectivity and subsequent polysomnographically (PSG) assessed sleep the same night in a sleep laboratory among individuals with documented insomnia. Methods We collected data from twenty participants (12 female; age=26.9, SD=6.6 years) meeting criteria for insomnia/sleep disorder. Each participant completed a baseline resting state functional connectivity (rsFC) scan in the early evening and then retired to their own private bedroom in a sleep laboratory. Participants were monitored throughout the night with polysomnography and evaluated for various sleep parameters. Data were analyzed using the CONN Toolbox, v17f. Total Sleep Time from PSG was extracted and entered as a covariate into the whole brain connectivity analysis. Connectivity across the regions identified in the Automated Anatomical Labeling Atlas was assessed using the ROI-to-ROI analysis approach, with a peak signal threshold of p < .001 (uncorrected) and False-Discovery-Rate (FDR) correction seed level correction. We focused on the anterior and posterior medial regions of the DMN. Results The analysis showed that TST was significantly negatively correlated with numerous regions throughout the brain (p<.05, FDR corrected), while there were no regions of positive connectivity. Consistent with our hypothesis, we found that greater TST was associated with anticorrelated activation between the anterior cingulate cortex and regions associated with language processing (i.e., Heschl’s gyrus), sensory motor function (precentral and postcentral gyri), superior temporal gyrus, parietal occipital gyrus, temporal pole, and occipital cortex. Conclusion Findings suggest that the connectivity of the anterior DMN with language, sensory, motor, and emotional processing regions is related to subsequent PSG measured sleep. Prior work has suggested that stronger anticorrelations between the DMN and task-positive regions is associated with better cognitive performance. Our findings also suggest that stronger anticorrelations between the anterior DMN and these other cortical regions are highly related to sleep among individuals with insomnia. Support (if any) W81XWH2010173

Instrument teachers’ practices, beliefs, and barriers regarding musical creativity: Exploring the creative process of interpretation

Instrumental music teaching traditionally emphasizes the cognitive, motor, and motivational processes of score reproduction, often at the expense of creative musical activities, such as improvisation or composition. Since today’s international art school curricula prominently include creativity competencies, opportunities to integrate creativity in instrumental lessons must be explored. This study investigates instrument teachers’ conception of musical creativity: its scope, opportunities, and risks. About 273 teachers completed an online questionnaire on their use of creative class time, beliefs, and barriers to creative instrument teaching. Although the majority acknowledged the benefits of creative activities for score-playing, they invested little in improvisation and composition due to a lack of time and training in musical creativity. Teachers considered interpretation a valuable form of musical creativity, next to improvisation and composition, but questioned its feasibility in instrument lessons. Implications for instrument-teacher training are discussed.

Novel multivariate methods to track frequency shifts of neural oscillations in EEG/MEG recordings

Instantaneous and peak frequency changes in neural oscillations have been linked to many perceptual, motor, and cognitive processes. Yet, the majority of such studies have been performed in sensor space and only occasionally in source space. Furthermore, both terms have been used interchangeably in the literature, although they do not reflect the same aspect of neural oscillations. In this paper, we discuss the relation between instantaneous frequency, peak frequency, and local frequency, the latter also known as spectral centroid. Furthermore, we propose and validate three different methods to extract source signals from multichannel data whose (instantaneous, local, or peak) frequency estimate is maximally correlated to an experimental variable of interest. Results show that the local frequency might be a better estimate of frequency variability than instantaneous frequency under conditions with low signal-to-noise ratio. Additionally, the source separation methods based on local and peak frequency estimates, called LFD and PFD respectively, provide more stable estimates than the decomposition based on instantaneous frequency. In particular, LFD and PFD are able to recover the sources of interest in simulations performed with a realistic head model, providing higher correlations with an experimental variable than multiple linear regression. Finally, we also tested all decomposition methods on real EEG data from a steady-state visual evoked potential paradigm and show that the recovered sources are located in areas similar to those previously reported in other studies, thus providing further validation of the proposed methods.

Study on heat transfer model of solid rocket motor combustor under high-temperature two-phase flow scour state

To address the issues with the multi-phase flow and heat transfer characteristics of the gas inside solid rocket motor combustor, this paper first establishes a mathematical model form that can express the heat transfer characteristics between gas and wall, and obtains the mathematical model of heat transfer by means of experiment and numerical simulation. The results show that heat transfer in the wall surface has obvious hysteresis during the actual working process of solid rocket motor, and that temperature in the wall surface will gradually reach the peak value after the motor works. The heat transfer trend between the numerical simulation results and the experimental data is relatively consistent, and the errors of heat transfer calculation in the stable working section of the motor can be controlled by 15%. It shows that the calculation model with the Sommerfeld number as the criterion selected in this paper can better reflect the heat transfer characteristics between the alumina droplet and the wall in combustor. The maximum error between the fitted value and calculated value is 9.43%, which indicates that the numerical model of heat transfer established under the state of two-phase gas and wall scouring has certain reliability.

The interaction between motor simulation and spatial perspective-taking in action language: a cross-cultural study

Growing evidence has revealed the crucial role of motor simulation and spatial perspective-taking in action language. However, there is still a lack of understanding of how motor and spatial processes interact when there are multiple actors involved, and if embodied processes are consistent across different cultures. To address this gap, we examined the interaction between motor simulation and spatial perspective-taking in action-sentences comprehension, along with the consistency of embodied processes across cultures. We collected data from Italian and US English speakers using an online sentence-picture verification task. The participants completed four conditions: two congruent (i.e., the participant is the agent in the sentence and the photo; the agent is someone else interacting with the participant in both the sentence and the picture) and two incongruent (i.e., the agents of the sentence and the picture do not match). The results show that when the perspective of the picture matched that described in the sentence-processing reaction times (RTs) were faster than in the incongruent conditions. In the congruent conditions where the agent is someone else, RTs were slower compared to the condition where the participant is the agent. This has been interpreted as claiming that motor simulation and perspective-taking are independent processes interacting during sentence comprehension (e.g., motor simulation is always run in the role of the agent, but we can adopt multiple perspectives depending on the pronouns and the contextual cues). Furthermore, Bayesian analysis provided evidence that embodied processing of action language entwines a common mechanism, suggesting cross-cultural consistency of embodied processes.

A meta-analysis of the association between movement specific reinvestment and motor performance

ABSTRACT The Movement Specific Reinvestment Scale (MSRS) is used to quantify differences in the propensity that individuals have to consciously engage in movement. Although the MSRS is widely used in movement science, evidence for its theoretically negative association with motor performance remains inconsistent. The aim of this meta-analysis was to summarize research findings between scores on the MSRS and motor performance, and to disentangle theoretical and sampling factors that may moderate the relationship. Following PRISMA guidelines, Web of Science, ProQuest, Google Scholar, PsychInfo and PubMed were searched. Out of the eligible texts, 410 effect sizes from 29 studies were extracted. Multi-level meta-analysis indicated that neither the MSRS total score, nor the MSRS subscales score (Movement Self-Consciousness and Conscious Motor Processing), were significantly associated with motor performance. However, the MSRS total score was significantly and negatively associated with motor performance when either (1) psychological pressure was present, (2) motor performance involved object manipulation, or (3) speed was the outcome unit of motor performance. In conclusion, the MSRS total score was linked to movement failure in certain motor conditions, providing partial support for the central tenet of the Theory of Reinvestment that a propensity for conscious engagement in movement can impair motor performance.

Aspects to Consider in the Evaluation of Photovoltaic System Projects to Avoid Problems in Power Systems and Electric Motors

This paper analyzes the problems in electrical power systems with high penetration of photovoltaic systems, which must be considered in evaluating new projects with these generation sources. The study analyzes the characteristics of photovoltaic systems, their generated effects, and proposals for technological improvements. The features of electric motors and their affectation when they are fed from networks with power quality problems are also described. As a result, the variability in energy production, the difficulties in frequency regulation, the increase in harmonics, and the instability in generating reactive power, are the main problems caused by the massive use of photovoltaic systems. Regarding electric motors, it is shown that harmonics and voltage regulation are the power quality problems that most affect their operation. None of the studies conducted analyzes the direct influence that photovoltaic systems can have on the process of electric motors. Considering the growth prospects for using photovoltaic systems and the importance of electric motors, it is suggested that the scientific community develop research focused on this problem.