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1.
Pilot Feasibility Stud ; 7(1): 150, 2021 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-34330330

RESUMO

BACKGROUND: This feasibility study investigated the viability of implementing a cognitive-based training program (NeuroTracker) and assessing its potential effects on academic performance for adolescents with extremely low IQ. METHODS: Twenty-six adolescents aged between 11 and 16 years with a Wechsler-based IQs in the extremely low range (MIQ = 56.00, SDIQ = 13.89) completed 15 training sessions on either the NeuroTracker or an active control task; math and reading performance were assessed using clinically validated instruments before and after training. Recruitment and retention rates, adherence, and properties of the academic measures were assessed. RESULTS: All recruited participants completed 15 training sessions within a 6-week period. Eighty-three percent of participants meeting initial inclusion criteria completed all stages of the study from baseline to post-intervention assessments. Some limitations of the academic measures were identified. CONCLUSIONS: Results suggest that implementing NeuroTracker as a classroom-based intervention and using clinically validated outcome measures is feasible with this population.

2.
PLoS One ; 16(3): e0247254, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-33724991

RESUMO

Having an optimal quality of vision as well as adequate cognitive capacities is known to be essential for driving safety. However, the interaction between vision and cognitive mechanisms while driving remains unclear. We hypothesized that, in a context of high cognitive load, reduced visual acuity would have a negative impact on driving behavior, even when the acuity corresponds to the legal threshold for obtaining a driving license in Canada, and that the impact observed on driving performance would be greater with the increase in the threshold of degradation of visual acuity. In order to investigate this relationship, we examined driving behavior in a driving simulator under optimal and reduced vision conditions through two scenarios involving different levels of cognitive demand. These were: 1. a simple rural driving scenario with some pre-programmed events and 2. a highway driving scenario accompanied by a concurrent task involving the use of a navigation device. Two groups of visual quality degradation (lower/ higher) were evaluated according to their driving behavior. The results support the hypothesis: A dual task effect was indeed observed provoking less stable driving behavior, but in addition to this, by statistically controlling the impact of cognitive load, the effect of visual load emerged in this dual task context. These results support the idea that visual quality degradation impacts driving behavior when combined with a high mental workload driving environment while specifying that this impact is not present in the context of low cognitive load driving condition.


Assuntos
Condução de Veículo/psicologia , Direção Distraída/psicologia , Tempo de Reação/fisiologia , Adulto , Atenção/fisiologia , Canadá , Cognição/fisiologia , Simulação por Computador , Feminino , Humanos , Masculino , Desempenho Psicomotor , Visão Ocular/fisiologia , Acuidade Visual/fisiologia , Percepção Visual/fisiologia
3.
J Neural Eng ; 2021 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-33711832

RESUMO

Brain-computer interfaces (BCI) have been used to control the gait of a virtual self-avatar with a proposed application in the field of gait rehabilitation. OBJECTIVE: to develop a high performance multi-modal BCI to control single steps and forward walking of an immersive virtual reality avatar. This system will overcome the limitation of existing systems. APPROACH: This system used MI of these actions, in cue-paced and self-paced modes. Twenty healthy participants participated in this 4 sessions study across 4 different days. They were cued to imagine a single step forward with their right or left foot, or to imagine walking forward. They were instructed to reach a target by using the MI of multiple steps (self-paced switch-control mode) or by maintaining MI of forward walking (continuous-control mode). The movement of the avatar was controlled by two calibrated RLDA classifiers that used the µ power spectral density (PSD) over the foot area of the motor cortex as a feature. The classifiers were retrained after every session. For a subset of the trials, positive modified feedback was presented to half of the participants. MAIN RESULTS: All participants were able to operate the BCI. Their average offline performance, after retraining the classifiers was 86.0 ± 6.1%, showing that the recalibration of the classifiers enhanced the offline performance of the BCI (p < 0.01). The average online performance was 85.9 ± 8.4% showing that modified feedback enhanced BCI performance (p =0.001). The average performance was 83% at self-paced switch control and 92% at continuous control mode. SIGNIFICANCE: This study reports on the first novel integration of different design approaches, different control modes and different performance enhancement techniques, all in parallel in one single high performance and multi-modal BCI system, to control single steps and forward walking of an immersive virtual reality avatar.

4.
Sci Rep ; 11(1): 4061, 2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33602994

RESUMO

This paper provides the framework and supporting evidence for a highly efficient closed-loop paradigm that modifies a classic learning scenario using real-time brain activity in order to improve learning performance in a perceptual-cognitive training paradigm known as 3-dimensional multiple object tracking, or 3D-MOT. Results demonstrate that, over 10 sessions, when manipulating this novel task by using real-time brain signals, speed and degree of learning can be substantially improved compared with a classic learning system or an active sham-control group. Superior performance persists even once the feedback signal is removed, which suggests that the effects of enhanced training are consolidated and do not rely on continued feedback. This type of learning paradigm could contribute to overcoming one of the fundamental limitations of neurofeedback and other cognitive enhancement techniques, a lack of observable transfer effects, by utilizing a method that can be directly integrated into the context in which improved performance is sought.

5.
PLoS One ; 15(12): e0240201, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33382720

RESUMO

Driving is an everyday task involving a complex interaction between visual and cognitive processes. As such, an increase in the cognitive and/or visual demands can lead to a mental overload which can be detrimental for driving safety. Compiling evidence suggest that eye and head movements are relevant indicators of visuo-cognitive demands and attention allocation. This study aims to investigate the effects of visual degradation on eye-head coordination as well as visual scanning behavior during a highly demanding task in a driving simulator. A total of 21 emmetropic participants (21 to 34 years old) performed dual-task driving in which they were asked to maintain a constant speed on a highway while completing a visual search and detection task on a navigation device. Participants did the experiment with optimal vision and with contact lenses that introduced a visual perturbation (myopic defocus). The results indicate modifications of eye-head coordination and the dynamics of visual scanning in response to the visual perturbation induced. More specifically, the head was more involved in horizontal gaze shifts when the visual needs were not met. Furthermore, the evaluation of visual scanning dynamics, based on time-based entropy which measures the complexity and randomness of scanpaths, revealed that eye and gaze movements became less explorative and more stereotyped when vision was not optimal. These results provide evidence for a reorganization of both eye and head movements in response to increasing visual-cognitive demands during a driving task. Altogether, these findings suggest that eye and head movements can provide relevant information about visuo-cognitive demands associated with complex tasks. Ultimately, eye-head coordination and visual scanning dynamics may be good candidates to estimate drivers' workload and better characterize risky driving behavior.


Assuntos
Atenção/fisiologia , Condução de Veículo/psicologia , Movimentos Oculares/fisiologia , Movimentos da Cabeça/fisiologia , Desempenho Psicomotor , Adulto , Cognição/fisiologia , Feminino , Humanos , Masculino , Assunção de Riscos , Treinamento por Simulação , Visão Ocular/fisiologia
6.
PeerJ ; 8: e10211, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-33240605

RESUMO

In the past 20 years, there has been growing research interest in the association between video games and cognition. Although many studies have found that video game players are better than non-players in multiple cognitive domains, other studies failed to replicate these results. Until now, the vast majority of studies defined video game players based on the number of hours an individual spent playing video games, with relatively few studies focusing on video game expertise using performance criteria. In the current study, we sought to examine whether individuals who play video games at a professional level in the esports industry differ from amateur video game players in their cognitive and learning abilities. We assessed 14 video game players who play in a competitive league (Professional) and 16 casual video game players (Amateur) on set of standard neuropsychological tests evaluating processing speed, attention, memory, executive functions, and manual dexterity. We also examined participants' ability to improve performance on a dynamic visual attention task that required tracking multiple objects in three-dimensions (3D-MOT) over five sessions. Professional players showed the largest performance advantage relative to Amateur players in a test of visual spatial memory (Spatial Span), with more modest benefits in a test of selective and sustained attention (d2 Test of Attention), and test of auditory working memory (Digit Span). Professional players also showed better speed thresholds in the 3D-MOT task overall, but the rate of improvement with training did not differ in the two groups. Future longitudinal studies of elite video game experts are required to determine whether the observed performance benefits of professional gamers may be due to their greater engagement in video game play, or due to pre-existing differences that promote achievement of high performance in action video games.

7.
J Vis ; 20(5): 9, 2020 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-32441736

RESUMO

Feedback is beneficial for learning. Nevertheless, it remains unclear whether (i) feedback draws attentional resources when integrated and (ii) the benefits of feedback for learning can be demonstrated using an attention-based task. We therefore (i) isolated feedback-specific load from task-specific load via individual differences in attention resource capacity and (ii) examined the effect of trial-by-trial feedback (i.e., present vs. absent) on learning a multiple object-tracking (MOT) paradigm. We chose MOT because it is a robust measure of attention resource capacity. In Study 1 participants tracked one (i.e., lowest attentional load condition) through four target items (i.e., highest load condition) among eight total items. One group (n = 32) received trial-by-trial feedback whereas the other group (n = 32) did not. The absence of feedback resulted in better MOT performance compared with the presence of feedback. Moreover, the difference in MOT capability between groups increased as the task-specific attentional load increased. These findings suggest that feedback integration requires attentional resources. Study 2 examined whether the absence (n = 19) or presence (n = 19) of feedback affects learning on the same MOT task across four testing days. When holding task-specific load constant, improvement in MOT was greater with feedback than without. Although this study is the first to isolate feedback-specific load in attention with MOT, more evidence is needed to demonstrate how the benefits of feedback translate to improvement on an attention-based task. These findings encourage future research to further explore the interaction between feedback, attention and learning.


Assuntos
Atenção/fisiologia , Retroalimentação Sensorial , Aprendizagem/fisiologia , Adulto , Cognição , Feminino , Humanos , Masculino , Adulto Jovem
8.
J Vis Exp ; (158)2020 04 30.
Artigo em Inglês | MEDLINE | ID: mdl-32420998

RESUMO

This paper presents a study protocol to measure the task-switching cost of using a smartphone while walking. This method involves having participants walk on a treadmill under two experimental conditions: a control condition (i.e., simply walking) and a multitasking condition (i.e., texting while walking). During these conditions, the participants must switch between the tasks related to the experimental condition and a direction determining task. This direction task is done with a point-light walker figure, seemingly walking towards the left or the right of the participant. Performance on the direction task represents the participant's task-switching costs. There were two performance measures: 1) correct identification of the direction and 2) response time. EEG data are recorded in order to measure the alpha oscillations and cognitive engagement occurring during the task switch. This method is limited in its ecological validity: pedestrian environments have many stimuli occurring simultaneously and competing for attention. Nonetheless, this method is appropriate for pinpointing task-switching costs. The EEG data allow the study of the underlying mechanisms in the brain that are related to differing task-switching costs. This design allows the comparison between task switching when doing one task at a time, as compared to task switching when multitasking, prior to the stimulus presentation. This allows understanding and pinpointing both the behavioral and neurophysiological impact of these two different task-switching conditions. Furthermore, by correlating the task-switching costs with the brain activity, we can learn more about what causes these behavioral effects. This protocol is an appropriate base for studying the switching cost of different smartphone uses. Different tasks, questionnaires, and other measures can be added to it in order to understand the different factors involved in the task-switching cost of smartphone use while walking.


Assuntos
Atenção/fisiologia , Encéfalo/fisiologia , Exercício Físico , Desempenho Psicomotor/fisiologia , Tempo de Reação/fisiologia , Smartphone/estatística & dados numéricos , Caminhada/fisiologia , Eletroencefalografia/métodos , Humanos , Smartphone/instrumentação
9.
Cogn Neurodyn ; 14(2): 155-168, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32226559

RESUMO

Understanding the neural mechanisms associated with time to contact (TTC) estimation is an intriguing but challenging task. Despite the importance of TTC estimation in our everyday life, few studies have been conducted on it, and there are still a lot of unanswered questions and unknown aspects of this issue. In this study, we intended to address one of these unknown aspects. We used independent component analysis to systematically assess EEG substrates associated with TTC estimation using two experiments: (1) transversal motion experiment (when a moving object passes transversally in the frontoparallel plane from side to side in front of the observer), and (2) head-on motion experiment (when the observer is on the motion path of the moving object). We also studied the energy of all EEG sources in these two experiments. The results showed that brain regions involved in the transversal and head-on motion experiments were the same. However, the energy used by some brain regions in the head-on motion experiment, including some regions in left parietotemporal and left frontal lobes, was significantly higher than the energy used by those regions in the transversal motion experiment. These brain regions are dominantly associated with different kinds of visual attention, integration of visual information, and responding to visual motion.

10.
Addict Behav ; 106: 106346, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32114216

RESUMO

Distracted walking is an ever-increasing problem. Studies have already shown that using a smartphone while walking impairs attention and increases the risk of accidents. This study seeks to determine if smartphone-addiction proneness magnifies the risks of using a smartphone while walking. In an experimental design, participants, while walking on a treadmill and engaged in a smartphone task, were required to switch tasks by responding to an external stimulus, i.e., determining the direction of movement of a point-light walker. Participants were chosen to cover a range of smartphone-addiction proneness. Four smartphone-use conditions were simulated: a control condition with no smartphone-use, an individual conversation condition, a gaming condition, and a group conversation condition. Our results show that using a smartphone while walking decreases accuracy and increases the number of missed stimuli. Moreover, participants with higher smartphone-addiction proneness scores were also prone to missing more stimuli, and this effect was found regardless of experimental condition. The effect of the smartphone task on accuracy and the number of missed stimuli was mediated by the emotional arousal caused by the smartphone task. Smartphone-addiction proneness was positively correlated with a declared frequency of smartphone use while walking. Furthermore, of all the smartphone tasks, the gaming condition was found to be the most distracting.


Assuntos
Smartphone , Caminhada , Atenção , Humanos , Inquéritos e Questionários
11.
Nanomaterials (Basel) ; 10(2)2020 Jan 28.
Artigo em Inglês | MEDLINE | ID: mdl-32012926

RESUMO

Porous Si-SiO2 UV microcavities are used to modulate a broad responsivity photodetector (GVGR-T10GD) with a detection range from 300 to 510 nm. The UV microcavity filters modified the responsivity at short wavelengths, while in the visible range the filters only attenuated the responsivity. All microcavities had a localized mode close to 360 nm in the UV-A range, and this meant that porous Si-SiO2 filters cut off the photodetection range of the photodetector from 300 to 350 nm, where microcavities showed low transmission. In the short-wavelength range, the photons were absorbed and did not contribute to the photocurrent. Therefore, the density of recombination centers was very high, and the photodetector sensitivity with a filter was lower than the photodetector without a filter. The maximum transmission measured at the localized mode (between 356 and 364 nm) was dominant in the UV-A range and enabled the flow of high energy photons. Moreover, the filters favored light transmission with a wavelength from 390 nm to 510 nm, where photons contributed to the photocurrent. Our filters made the photodetector more selective inside the specific UV range of wavelengths. This was a novel result to the best of our knowledge.

12.
Brain Inj ; 34(3): 385-389, 2020 02 23.
Artigo em Inglês | MEDLINE | ID: mdl-32013583

RESUMO

PRIMARY OBJECTIVE: This study aimed to explore the potential for the Neurotracker, a perceptual-cognitive, multiple-object tracking test, and train paradigm, as a marker of functional recovery after mild traumatic brain injury (mTBI). It is hypothesized that Neurotracker could serve as a proxy for assessing cerebral functioning. RESEARCH DESIGN: A comparative, 6 time points, longitudinal study design was used to compare Neurotracker performance between children and adolescents who were clinically recovered from mTBI and healthy controls. METHODS AND PROCEDURES: Clinical measures were collected at the initial and final visits. Neurotracker trainings were performed at each of the 6 visits. Speed thresholds (Neurotracker performance) were recorded at each visit. MAIN OUTCOMES AND RESULTS: A two-way repeated measures ANOVA suggested no differences between the groups but a significant time effect was apparent. CONCLUSIONS: Clinically recovered children and adolescents exhibit similar training abilities to control subjects on this task. These results support further investigations using Neurotracker as a marker of recovery following mTBI.

13.
Sci Rep ; 10(1): 2220, 2020 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-32041997

RESUMO

Obtaining silicon-based photonic-structures in the ultraviolet range would expand the wavelength bandwidth of silicon technology, where it is normally forbidden. Herein, we fabricated porous silicon microcavities by electrochemical etching of alternating high and low refraction index layers; and were carefully subjected to two stages of dry oxidation at 350 °C for 30 minutes and 900 °C, with different oxidation times. In this way, we obtained oxidized porous silicon that induces a shift of a localized mode in the ultraviolet region. The presence of Si-O-Si bonds was made clear by FTIR absorbance spectra. High-quality oxidized microcavities were shown by SEM, where their mechanical stability was clearly visible. We used an effective medium model to predict the refractive index and optical properties of the microcavities. The model can use either two or three components (Si, SiO2, and air). The latter predicts that the microcavities are made almost completely of SiO2, implying less photon losses in the structure. The theoretical photonic-bandgap structure and localized photonic mode location showed that the experimental spectral peaks within the UV photonic bandgap are indeed localized modes. These results support that our oxidation process is very advantageous to obtain complex photonic structures in the UV region.

14.
Comput Intell Neurosci ; 2019: 2503431, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31687005

RESUMO

A brain-computer interface (BCI) decodes the brain signals representing a desire to do something and transforms those signals into a control command. However, only a limited number of mental tasks have been previously investigated and classified. This study aimed to investigate two motor imagery (MI) commands, moving forward and moving backward, using a small number of EEG channels, to be used in a neurofeedback context. This study also aimed to simulate a BCI and investigate the offline classification between MI movements in forward and backward directions, using different features and classification methods. Ten healthy people participated in a two-session (48 min each) experiment. This experiment investigated neurofeedback of navigation in a virtual tunnel. Each session consisted of 320 trials where subjects were asked to imagine themselves moving in the tunnel in a forward or backward motion after a randomly presented (forward versus backward) command on the screen. Three electrodes were mounted bilaterally over the motor cortex. Trials were conducted with feedback. Data from session 1 were analyzed offline to train classifiers and to calculate thresholds for both tasks. These thresholds were used to form control signals that were later used online in session 2 in neurofeedback training to trigger the virtual tunnel to move in the direction requested by the user's brain signals. After 96 min of training, the online band-power neurofeedback training achieved an average classification of 76%, while the offline BCI simulation using power spectral density asymmetrical ratio and AR-modeled band power as features, and using LDA and SVM as classifiers, achieved an average classification of 80%.


Assuntos
Interfaces Cérebro-Computador , Encéfalo/fisiologia , Neurorretroalimentação/fisiologia , Realidade Virtual , Simulação por Computador , Eletroencefalografia/métodos , Feminino , Humanos , Masculino
15.
Percept Mot Skills ; 126(5): 922-948, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31272277

RESUMO

This study introduces a virtual life-sized perceptual-cognitive training paradigm that combines three-dimensional multiple object tracking (3D-MOT) with motor (Experiment 1) or perceptual (Experiment 2) sport decision-making tasks. We sought to assess the impact of training on task performance and determine optimal training conditions for improvement and learning. Fifty-seven participants were randomly assigned to one of four training conditions (isolated 3D-MOT, 3D-MOT combined with a decision-making task, consolidated 3D-MOT later combined with a decision-making task, and isolated decision-making task). We evaluated task performance using speed thresholds, success rate (%), and reaction time (s). Findings were that the dual-task paradigm was associated with performance beyond chance level on both 3D-MOT and decision-making tasks despite an important dual-task cost. Interestingly, the results seemed to favor consolidated 3D-MOT training over simultaneous 3D-MOT training when combined with a motor decision-making task but not when combined with a perceptual decision-making task. The number of shared attentional resources in the nature of the additional task (i.e., perceptual or motor decision-making) seems to be key in interpreting the dual-task interference. These findings must be considered when designing representative multitask perceptual-cognitive training.


Assuntos
Desempenho Atlético , Cognição , Tomada de Decisões , Treinamento por Simulação/métodos , Realidade Virtual , Adulto , Atenção , Feminino , Humanos , Aprendizagem , Masculino , Tempo de Reação , Esportes , Análise e Desempenho de Tarefas , Adulto Jovem
16.
J Neural Eng ; 16(5): 051001, 2019 08 14.
Artigo em Inglês | MEDLINE | ID: mdl-31151119

RESUMO

CONTEXT: Electroencephalography (EEG) is a complex signal and can require several years of training, as well as advanced signal processing and feature extraction methodologies to be correctly interpreted. Recently, deep learning (DL) has shown great promise in helping make sense of EEG signals due to its capacity to learn good feature representations from raw data. Whether DL truly presents advantages as compared to more traditional EEG processing approaches, however, remains an open question. OBJECTIVE: In this work, we review 154 papers that apply DL to EEG, published between January 2010 and July 2018, and spanning different application domains such as epilepsy, sleep, brain-computer interfacing, and cognitive and affective monitoring. We extract trends and highlight interesting approaches from this large body of literature in order to inform future research and formulate recommendations. METHODS: Major databases spanning the fields of science and engineering were queried to identify relevant studies published in scientific journals, conferences, and electronic preprint repositories. Various data items were extracted for each study pertaining to (1) the data, (2) the preprocessing methodology, (3) the DL design choices, (4) the results, and (5) the reproducibility of the experiments. These items were then analyzed one by one to uncover trends. RESULTS: Our analysis reveals that the amount of EEG data used across studies varies from less than ten minutes to thousands of hours, while the number of samples seen during training by a network varies from a few dozens to several millions, depending on how epochs are extracted. Interestingly, we saw that more than half the studies used publicly available data and that there has also been a clear shift from intra-subject to inter-subject approaches over the last few years. About [Formula: see text] of the studies used convolutional neural networks (CNNs), while [Formula: see text] used recurrent neural networks (RNNs), most often with a total of 3-10 layers. Moreover, almost one-half of the studies trained their models on raw or preprocessed EEG time series. Finally, the median gain in accuracy of DL approaches over traditional baselines was [Formula: see text] across all relevant studies. More importantly, however, we noticed studies often suffer from poor reproducibility: a majority of papers would be hard or impossible to reproduce given the unavailability of their data and code. SIGNIFICANCE: To help the community progress and share work more effectively, we provide a list of recommendations for future studies and emphasize the need for more reproducible research. We also make our summary table of DL and EEG papers available and invite authors of published work to contribute to it directly. A planned follow-up to this work will be an online public benchmarking portal listing reproducible results.


Assuntos
Interfaces Cérebro-Computador/tendências , Encéfalo/fisiologia , Aprendizado Profundo/tendências , Eletroencefalografia/tendências , Bases de Dados Factuais/tendências , Eletroencefalografia/métodos , Humanos
17.
Accid Anal Prev ; 127: 1-8, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30826692

RESUMO

Texting while walking has been highlighted as a dangerous behavior that leads to impaired judgment and accidents. This impairment could be due to task switching which involves activation of the present task and the inhibition of the previous task. However, the relative contributions of these processes and their brain activity have not yet been studied. We addressed this gap by asking participants to discriminate the orientation of an oncoming human shape in a virtual environment while they were: i) walking on a treadmill, or ii) texting while walking on a treadmill. Participants' performance (i.e., correctly identifying if a walker would pass them to their left or right) and electroencephalography (EEG) data was collected. Unsurprisingly, we found that participants performed better while they were only walking than when texting while walking. However, we also found that the diminished performance is differently related to task set inhibition and task set activation in the two conditions. The alpha oscillations, which can be used as an index of task inhibition, have a significantly different relation to performance in the two conditions, the relation being negative when subjects are texting. This may indicate that the more inhibition is needed, the more the performance is affected by texting. To our knowledge, this is the first study to investigate the brain signature of task switching in texting while walking. This finding is the first step in identifying the source of impaired judgment in texting pedestrians and in finding viable solutions to reduce the risks.


Assuntos
Atenção/fisiologia , Envio de Mensagens de Texto , Caminhada/fisiologia , Adulto , Estudos de Casos e Controles , Teste de Esforço/métodos , Feminino , Humanos , Masculino , Orientação Espacial/fisiologia , Pedestres , Análise e Desempenho de Tarefas
18.
Knee ; 26(1): 52-60, 2019 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-30583887

RESUMO

BACKGROUND: A large majority of anterior cruciate ligament (ACL) injuries are non-contact, most often occurring during a landing or change of direction. Recent research indicates that cognitive factors may be involved in non-contact ACL injuries. The aim of this study was to determine if a game-situation perceptual-cognitive load leads to altered landing kinematics in physically fatigued female athletes. METHODS: Nineteen female recreational athletes were recruited to perform a series of jumping and landing trials. In a first phase, eight trials were performed in an isolated condition and eight were performed while participants performed a perceptual-cognitive task. Before a second identical phase, participants underwent a muscular fatigue protocol. Knee-joint kinematics were recorded and compared between conditions using paired t-tests. RESULTS: Muscle fatigue led to statistically significant increases in peak knee abduction and peak internal knee rotation as well as a decrease in maximum knee flexion, when comparing conditions without the perceptual-cognitive task. The perceptual-cognitive task had no statistically significant effect on any knee rotations, either pre- or post-fatigue. However, a subgroup of 12 athletes showed a significant increase in knee abduction in the presence of the perceptual-cognitive task, only in the fatigued condition. CONCLUSION: A perceptual-cognitive task combined with muscle fatigue alters knee kinematics of landing for a subset of recreational athletes, potentially increasing the risk of ACL rupture. Further studies are necessary to confirm this finding and to identify characteristics of at-risk individuals to target them for injury prevention protocols.


Assuntos
Atletas , Cognição/fisiologia , Articulação do Joelho/fisiologia , Movimento/fisiologia , Fadiga Muscular/fisiologia , Adulto , Fenômenos Biomecânicos , Feminino , Humanos , Masculino
19.
BMJ Open Sport Exerc Med ; 4(1): e000384, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30305922

RESUMO

Objectives: While the rate of sport-related concussion is increasing, more effective tools are needed to help monitor the diagnosis and return to play of athletes. The three-dimensional multiple-object tracking (3D-MOT) exercise is a perceptual-cognitive task that has shown predictive power towards the dynamic requirements of real-world activities such as sport. This study introduced the use of the 3D-MOT task, along with the Standardized Assessment of Concussion (SAC) and Modified Balance Error Scoring System (M-BESS) tests, for diagnosis and return to play in professional sports. Methods: Fifty-nine professional athletes were tested with the 3D-MOT, SAC and M-BESS tests at 48 hours following the injury. The same measures were employed to evaluate the return to play following the standard concussion management protocol. The SAC and M-BESS tests were also performed in pre-season (baseline) in 32 out of the 59 athletes. Results: The injured athletes exhibited poor performance on 3D-MOT at 48 hours post injury compared with return to play (p<0.001) as well as compared with healthy professionals' performance scores (p<0.001). Importantly, learning rate, which participants are thought to have an expert advantage on this perceptual-cognitive task, was totally disrupted at 48 hours post injury compared with healthy professionals (p<0.001). The 3D-MOT performance was also correlated to the total number of symptoms (p=0.020), SAC (p=0.031) and M-BESS (p=0.004) scores at 48 hours. Not surprisingly, SAC and M-BESS tests' usefulness for monitoring concussion was found to be weak, particularly when test performance following the injury was compared to baseline (p=0.056 and 0.349 for SAC and M-BESS, respectively). Conclusion: 3D-MOT could help monitor sport-related concussion in professional athletes. The discussion also covers the critical importance of perceptual-cognitive assessment following concussion in the athletic population.

20.
Materials (Basel) ; 11(5)2018 May 21.
Artigo em Inglês | MEDLINE | ID: mdl-29883393

RESUMO

Photonic crystals have been an object of interest because of their properties to inhibit certain wavelengths and allow the transmission of others. Using these properties, we designed a photonic structure known as photodyne formed by two porous silicon one-dimensional photonic crystals with an air defect between them. When the photodyne is illuminated with appropriate light, it allows us to generate electromagnetic forces within the structure that can be maximized if the light becomes localized inside the defect region. These electromagnetic forces allow the microcavity to oscillate mechanically. In the experiment, a chopper was driven by a signal generator to modulate the laser light that was used. The driven frequency and the signal modulation waveform (rectangular, sinusoidal or triangular) were changed with the idea to find optimal conditions for the structure to oscillate. The microcavity displacement amplitude, velocity amplitude and Fourier spectrum of the latter and its frequency were measured by means of a vibrometer. The mechanical oscillations are modeled and compared with the experimental results and show good agreement. For external frequency values of 5 Hz and 10 Hz, the best option was a sinusoidal waveform, which gave higher photodyne displacements and velocity amplitudes. Nonetheless, for an external frequency of 15 Hz, the best option was the rectangular waveform.

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