Executive Functions and Motor Adaptation to Predictable and Unpredictable Perturbations.

In this study, we aimed to investigate the influence of executive functions (EF) on motor adaptation. We compared the motor performance of adults with and without EF deficits. Those with EF deficits (n = 21) were individuals with attention deficit hyperactivity disorder (ADHD) under medical treatment, and those without EF deficits (n = 21) comprised a control group (CG) of participants who were also without neurological or psychiatric diagnoses. Both groups performed a complex coincident timing motor task and various computerized neuropsychological tests for assessing EF. To investigate motor adaptation, the motor task provided measures of absolute error (AE) and variable error (VE) to reflect, respectively, performance accuracy and consistency relative to the task goal. We used reaction time (RT) to measure planning time taken before starting the task. First, participants practiced until they reached a criterion of performance stabilization (prior to their exposure to motor perturbations). They were next exposed to fast and slow predictable and unpredictable perturbations. On all neuropsychological tasks, participants with ADHD scored more poorly than control participants (p < .05); participants with ADHD also performed worse than control participants on all motor measures, particularly under unpredictable perturbations (p < .05). Under slow perturbations, EF deficits, particularly attentional impulsivity, negatively affected motor adaptation while cognitive flexibility was related to performance improvement. Under fast perturbations, both impulsivity and fast reaction time were related to improvement in motor adaptation under both predictable and unpredictable perturbations. We discuss the research and practical implications of these findings.

Transcranial Direct Current Stimulation: No Effect on Aerobic Performance, Heart Rate, or Rating of Perceived Exertion in a Progressive Taekwondo-Specific Test.

PURPOSE: To investigate the effects of anodal transcranial direct current stimulation (a-tDCS) on the aerobic performance, heart rate (HR), and rating of perceived exertion (RPE) of highly trained taekwondo athletes. METHODS: Twelve (8 men and 4 women) international/national-level athletes received a-tDCS or sham treatment over the M1 location in a randomized, single-blind crossover design. The stimulation was delivered at 1.5 mA for 15 min using an extracephalic bihemispheric montage. Athletes performed the progressive-specific taekwondo test 10 min after stimulation. HR was monitored continuously during the test, and RPE was registered at the end of each stage and at test cessation. RESULTS: There were no significant differences between sham and a-tDCS in time to exhaustion (14.6 and 14.9, respectively, P = .53, effect size = 0.15) and peak kicking frequency (52 and 53.6, respectively, P = .53, effect size = 0.15) or in HR (P > .05) and RPE responses (P > .05). CONCLUSIONS: Extracephalic bihemispheric a-tDCS over M1 did not influence the aerobic performance of taekwondo athletes or their psychophysiological responses, so athletes and staff should be cautious when using it in a direct-to-consumer manner.

Self-Controlled Feedback and Learner Impulsivity in Sequential Motor Learning.

Many studies have attributed self-controlled feedback benefits associated with motor learning to learners' greater information processing during practice. However, individual learner characteristics like their impulsivity can also influence how people engage cognitively during learning. We investigated possible dissociations between the types of interaction in self-controlled knowledge of results (KR) and learner impulsivity levels in learning a sequential motor task. Ninety volunteers responded to the self-restraint section of the Barkley deficits in executive functioning scale, and those 60 participants with the highest ( n = 30) and lowest ( n = 30) impulsivity scores practiced a motor task involving sequential pressing of four keys in predetermined absolute and relative times. We further divided participants into four experimental groups by assigning the high- and low-impulsivity groups to two forms of KR-self-controlled absolute and yoked. Study results showed no interaction effect between impulsivity and self-controlled KR, and, contrary to expectation, self-controlled KR did not benefit learning, independently of impulsivity. However, low-impulsivity participants performed better than high-impulsivity participants on the absolute dimension of the transfer task, while high-impulsivity learners were better at the relative dimension. Cognitive characteristics of automatic and reflexive processing were expressed by the strategies used to direct attention to relative and absolute task dimensions, respectively. Low-impulsivity learners switched their attention to both dimensions at the end of practice, while high-impulsivity learners did not switch their attention or directed it only to the relative dimension at the end of the practice. These results suggest that the cognitive styles of high- and low-impulsive learners differentially favor learning distinct dimensions of a motor task, regardless of self-controlled KR.

Tactical Knowledge, Decision-Making, and Brain Activation Among Volleyball Coaches of Varied Experience.

This study compared decision-making (DM) of experienced and novice volleyball coaches while measuring blood flow brain activation with functional near-infrared spectroscopy. We sampled 34 coaches (mean [ M] age of 32.5, standard deviation [ SD] = 9.4 years) divided into two experience groups: (a) novice ( M = 2.8, SD = 1.9 years) and (b) experienced (M = 19, SD = 7.2 years). We evaluated coaches' DM through their responses to video-based scenarios of attacks performed in the extremities of the net within the Declarative Tactical Knowledge Test in Volleyball. We found no significant DM differences between the two groups of coaches ( p = .063), though novice (vs. experienced) coaches showed greater blood flow of the prefrontal cortex when visualizing the game situations. While experienced coaches may have better prefrontal neural efficiency during DM in these situations, further research is needed to evaluate other cerebral areas; since blood flow is an indirect measure of neural efficiency, and activity in remaining cortical components was unknown in this study.

Differences in motor control of an aiming task in different group ages of the elderly

This study aimed to investigate how different age groups of older adults perform and control movements in a goal-directed aiming task and the importance of visual feedback during these movements. Methods: Participants included 22 old adults, divided in two age groups: younger (60-70 yr) and older (80-90 yr). Subjects performed the task in a condition with vision and in a condition where vision was deprived. Results: In the vision condition, younger subjects showed smaller movement and reaction times, smaller radial errors, higher peak velocities, lower relative times to reach peak velocity than older subjects. In the vision-deprived condition the same results were found, except for radial error measure, where no significant effect for age groups was found. Conclusion: Younger subjects seemed to rely more on visual online feedback than older subjects and older subjects use other sensory sources to meet the possible deficits of information obtained by vision.(AU)

Translation, Adaptation, and Validation of the Brazilian Version of the Dickman Impulsivity Inventory (Br-DII).

Impulsivity has mainly been described as a negative or dysfunctional characteristic associated with several disorders. However, impulsivity is not only related to dysfunctional outcomes and may explain individual differences in optimal human functioning as well. The Dickman Impulsivity Inventory (DII) is a self-report instrument measuring both the dysfunctional and the functional aspects of impulsivity. In this study, we performed the translation and cultural adaptation of the DII to the Brazilian context and analyzed its psychometric properties. Translation and cultural adaptation followed a rigorous process, which relied on an expert panel in the cross-cultural adaptation of psychological instruments. Data from 405 undergraduate students were obtained for the Brazilian version of the DII (Br-DII). The 23 items of the Br-DII was considered unsuitable according to model fit indices of the Confirmatory Factor Analysis (both for Oblique and Orthogonal models). Exploratory Factor Analysis showed an 18 items version of the Br-DII to be suitable (CFI = 0.92; TLI = 0.90, and RMSEA = 0.057). The DII's 18 items version also showed adequate Cronbach's alpha, intraclass correlation coefficient, and convergent and discriminant validity with the BIS-11. Therefore, the Br-DII demonstrated reliability and validity in the measurement of functional and dysfunctional impulsivity.

Task engagement and mental workload involved in variation and repetition of a motor skill.

Explanatory hypotheses proposed in behavioral studies assumed that less repetitive practice schedules, such as random practice, seem to demand greater cognitive effort than more repetitive types of practice organization, such as constant. All of these hypotheses emphasize the enhanced demand to memory processes promoted by less repetitive practice schedules. In the present study, we investigated the cognitive effort involved in random and constant practice schedules with an electrophysiological approach. Twenty-one male participants practiced a sequential key-pressing task with two goals: learning the relative timing dimension and learning the absolute timing dimension. Sixty trials were performed in a constant practice schedule (only one absolute timing goal), and sixty trials were performed in random order (three absolute timing goals). Two electroencephalography based measures of cognitive states were used: (a) task engagement (sensory processing and attention resources) and (b) mental workload (working memory load). The results showed that random practice induced greater cognitive effort than constant practice when task engagement was analyzed. Throughout practice, both task engagement and mental workload decreased more in the constant practice condition than in the random practice condition. The increased demand for sensory processing observed in random practice opens a new exciting field of study in practice organization.

The level of performance stabilization influences motor adaptation on an isometric force control task.

This study compared the effects of two levels of performance stabilization on the adaptation to unpredictable perturbations in an isometric control force task with the goal of controlling 40% of the maximum force. The experiment consisted of pre-exposure and exposure phases. In the pre-exposure two levels of performance stabilization were manipulated: a stabilization group (SG) performed three trials in a row while maintaining 40% of the maximum force for three seconds and an absolute error less than or equal to 5% (i.e., the criteria of performance), and a superstabilization group (SSG) performed six blocks of the same criteria. During the exposure phase, the task was the same as that in the pre-exposure phase; however, it was inserted 9 trials of perturbations when the task goal changed to 60% of the maximum force. We measured the %RMSE, RMS from the biceps and triceps brachii and co-contraction. In the pre-exposure phase, both groups showed similar performance and muscle activity. When exposed to the perturbations, SSG performance more quickly returned to the previous level of accuracy, showed lower muscle activation and demonstrated a greater muscle co-contraction than did SG. The results give support to the adaptive process model on motor learning.

Can Eye Fixation During the Grooved Pegboard Test Distinguish Between Planning and Online Correction?

The Grooved Pegboard Test, in its standard use, has well-documented utility. However, a revised methodology needs further study, leading us to investigate whether duration of eye fixation could predict performance on different task conditions of the Grooved Pegboard Test (place and remove pegs) with the preferred and nonpreferred hands. Fifty-two right-handed undergraduate students (33 male and 19 female), with a mean age of 22.22 (±3.57) years, performed the Grooved Pegboard Test. SensoMotoric eye-tracking glasses with a binocular time resolution of 30 Hz were used to measure eye fixation. The videos were recorded in iView software, and data were analyzed using BeGaze software. The number and duration of eye fixations were statistically different with preferred and nonpreferred hands and also differed across tasks. Simple linear regression showed eye fixation duration to predict movement time in the place task (preferred hand: R2 = 31%; nonpreferred hand: R2 = 41%) and in the remove task (preferred hand: R2 = 11%; nonpreferred hand: R2 = 25%). Thus, duration of eye fixation during the Grooved Pegboard Test differentially predicted performance with each hand and on preferred and different subtests of this instrument.

Impairment of fine motor dexterity in mild cognitive impairment and alzheimer's disease dementia: association with activities of daily living

Objective: Cognitive impairment is a hallmark of mild cognitive impairment (MCI) and Alzheimer’s disease dementia (AD). Although the cognitive profile of these patients and its association with activities of daily living (ADLs) is well documented, few studies have assessed deficits in fine motor dexterity and their association with ADL performance. The objective of this research paper is to evaluate fine motor dexterity performance among MCI and AD patients and to investigate its association with different aspects of ADLs. Methods: We assessed normal aging controls, patients with multiple- and single-domain amnestic MCI (aMCI), and patients with mild AD. Fine motor dexterity was measured with the Nine-Hole Peg Test and cognitive functioning by the Mattis Dementia Rating Scale. We analyzed the data using general linear models. Results: Patients with AD or multiple-domain aMCI had slower motor responses when compared to controls. AD patients were slower than those with single-domain aMCI. We found associations between cognition and instrumental ADLs, and between fine motor dexterity and self-care ADLs. Conclusion: We observed progressive slowing of fine motor dexterity along the normal aging-MCI-AD spectrum, which was associated with autonomy in self-care ADLs.

Impairment of fine motor dexterity in mild cognitive impairment and Alzheimer's disease dementia: association with activities of daily living.

OBJECTIVE: Cognitive impairment is a hallmark of mild cognitive impairment (MCI) and Alzheimer's disease dementia (AD). Although the cognitive profile of these patients and its association with activities of daily living (ADLs) is well documented, few studies have assessed deficits in fine motor dexterity and their association with ADL performance. The objective of this research paper is to evaluate fine motor dexterity performance among MCI and AD patients and to investigate its association with different aspects of ADLs. METHODS: We assessed normal aging controls, patients with multiple- and single-domain amnestic MCI (aMCI), and patients with mild AD. Fine motor dexterity was measured with the Nine-Hole Peg Test and cognitive functioning by the Mattis Dementia Rating Scale. We analyzed the data using general linear models. RESULTS: Patients with AD or multiple-domain aMCI had slower motor responses when compared to controls. AD patients were slower than those with single-domain aMCI. We found associations between cognition and instrumental ADLs, and between fine motor dexterity and self-care ADLs. CONCLUSION: We observed progressive slowing of fine motor dexterity along the normal aging-MCI-AD spectrum, which was associated with autonomy in self-care ADLs.

Repetition and variation in motor practice: A review of neural correlates.

Random practice results in more effective motor learning than either constant or blocked practice. Recent studies have investigated the effects of practice schedules at the neurophysiological level. This study aims to conduct a literature review of the following issues: (a) the differential involvement of premotor areas, the primary motor cortex, the dorsolateral prefrontal cortex and the posterior parietal cortex in different types of practice; (b) changes in the participation of these areas throughout practice; and (c) the degree of support that current neurophysiological findings offer to strengthen the behavioral proposition that distinct cognitive processes are generated by different practice schedules. Data from 10 studies that investigated associations between practice structures and neurobiological substrates were analyzed. The participation of the indicated areas was found to depend on practice structure and varied during the learning process. Greater cognitive engagement was associated with random practice. In conclusion, distinct neural processes are engendered by different practice conditions. The integration of behavioral and neurophysiological findings promotes a more comprehensive view of the phenomenon.

THE RELATIVE AGE EFFECT IN COMBAT SPORTS: AN ANALYSIS OF OLYMPIC JUDO ATHLETES, 1964-2012.

This study assessed the relative age effect (RAE) in judo athletes who participated in the Olympic Games from 1964 to 2012. The names and birthdates of the Olympic judo athletes were collected from open-access websites. Data from male (n=1,762) and female (n=665) competitors were analyzed separately. Chi-squared tests were performed to investigate REA in medalists, and by weight categories and sexes. When the analyses used semesters to divide the period when the athletes were born, a RAE was found in male heavyweight athletes and male medallists. Thus, in a selected group of judo athletes who had participated at the highest competitive level, RAEs were present in both athletes who won Olympic medals and heavyweight athletes in the male group.

Effects of knowledge of results frequency on the learning of generalized motor programs and parameters under conditions of constant practice.

The present study investigated the effects of the frequency of knowledge of results (KR) on both generalized motor programs and parameters. Two experiments were conducted that compared two frequencies of KR in terms of generalized motor programs and parameters: (1) the first experiment compared the effects of KR frequency on generalized motor programs in the 100% and 50% groups; and (2) the second experiment compared the effects of reduced KR frequency on parameters in the 100% and 50% groups. In the first experiment, results showed that the 50% group exhibited smaller relative timing errors than did the 100% group, but absolute timing errors in the transfer test were similar between these two groups. In the second experiment, both groups exhibited similar relative and absolute timing errors. These results suggested that the beneficial effects of reduced KR frequency were restricted to generalized motor programs.

Association between the catechol-O-methyltransferase (COMT) Val158Met polymorphism and manual aiming control in healthy subjects.

BACKGROUND: Prefrontal dopamine is catabolized by the catechol-O-methyltransferase (COMT) enzyme. Current evidence suggests that the val/met single nucleotide polymorphism in the COMT gene can predict the efficiency of executive cognition in humans. Individuals carrying the val allele perform more poorly because less synaptic dopamine is available. METHODOLOGY/PRINCIPAL FINDINGS: We investigated the influence of the COMT polymorphism on motor performance in a task that requires different executive functions. We administered a manual aiming motor task that was performed under four different conditions of execution by 111 healthy participants. Participants were grouped according to genotype (met/met, met/val, val/val), and the motor performance among groups was compared. Overall, the results indicate that met/met carriers presented lower levels of peak velocity during the movement trajectory than the val carriers, but met/met carriers displayed higher accuracy than the val carriers. CONCLUSIONS/SIGNIFICANCE: This study found a significant association between the COMT polymorphism and manual aiming control. Few studies have investigated the genetics of motor control, and these findings indicate that individual differences in motor control require further investigation using genetic studies.

Sensorimotor performance in euthymic bipolar disorder: the MPraxis (PennCNP) analysis.

BACKGROUND: Sensorimotor deficits are an important phenomenological facet observed in patients with bipolar disorder (BD). However, there is little research on this topic. We hypothesize that the MPraxis test can be used to screen for motor impairments in BD aiming movements. METHOD: The MPraxis, which is a quick and easy-to-apply computerized test, measures sensorimotor control. During the test, the participant must move the computer mouse cursor over an ever-shrinking green box and click on it once. We predict that the MPraxis test is capable of detecting differences in sensorimotor performance between patients with BD and controls. We assessed 21 euthymic type I BD patients, without DSM-IV-TR Axis I comorbidity, and 21 healthy controls. RESULTS AND CONCLUSIONS: Compared to the controls, the patients with BD presented a lower response time in their movements in all conditions. Our results showed sensorimotor deficits in BD and suggested that the MPraxis test can be used to screen for motor impairments in patients with euthymic BD.

A kinematic analysis of manual aiming control on euthymic bipolar disorder.

Motor deficits in tasks that require force steadiness or scaling of movement velocity have been found in bipolar disorder (BD). A potential explanation for these results is the abnormal functioning of the frontostriatal circuitry. We designed this study to investigate the possible impairments in a manual aiming task. Participants comprised 15 euthymic BD patients and 15 healthy controls, who performed 100 trials of a goal-directed manual movement with a non-inking pen on a digitizing tablet. Four different conditions of execution were required. The control condition appeared on the computer screen in 70% of the trials, and the other three conditions, (a) distractor, (b) inhibition of response and (c) higher index of difficulty, each appeared in 10% of the trials. Compared to the controls, the BD patients were less fluent in their movements, relied more heavily on visual feedback to control their manual movements and presented a lower spatial accuracy. We found that motor deficits in euthymic BD were observed in the kinematic analysis of manual aiming. Our findings are consistent with the hypothesis of abnormal functioning of the frontostriatal circuitry in euthymic BD.

Impulsivity and the 5-HTTLPR polymorphism in a non-clinical sample.

BACKGROUND: Impulsivity has been associated with serotonergic system functions. However, few researchers have investigated the relationship between a polymorphism in the promoter of the serotonin transporter gene (5-HTTLPR) and the different components of impulsivity in a non-clinical population. The aim of this study was to investigate the relationship between a polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) and the different components of impulsivity in a non-clinical population. METHODOLOGY/PRINCIPAL FINDINGS: We administered two neuropsychological tests, the Continuous Performance Task and the Iowa Gambling Task, to 127 healthy participants to measure their levels of motor, attentional and non-planning impulsivity. Then, these participants were grouped by genotype and gender, and their scores on impulsivity measures were compared. There were no significant differences between group scores on attentional, motor and non-planning impulsivity. CONCLUSIONS/SIGNIFICANCE: Our results suggest that 5-HTTLPR genotype is not significantly associated with subsets of impulsive behavior in a non-clinical sample when measured by neuropsychological tests. These findings are discussed in terms of the sensitivity of neuropsychological tests to detect impulsivity in a non-clinical population and the role of gender and race in the relationship between the 5-HTTLPR and impulsivity.