Brain dynamics of visual anticipation during spatial occlusion tasks in expert tennis players

Stimulus identification and action outcome understanding for a rapid and accurate response selection, play a fundamental role in racquet sports. Here, we investigated the neurodynamics of visual anticipation in tennis manipulating the postural and kinematic information associated with the body of opponents by means of a spatial occlusion protocol. Event Related Potentials (ERPs) were evaluated in two groups of professional tennis players (N = 37) with different levels of expertise, while they observed pictures of opponents and predicted the landing position as fast and accurately as possible. The observed action was manipulated by deleting different body districts of the opponent (legs, ball, racket and arm, trunk). Full body image (no occlusion) was used as control condition. The worst accuracy and the slowest response time were observed in the occlusion of trunk and ball. The former was associated with a reduced amplitude of the ERP components likely linked to body processing (the N1 in the right hemisphere) and visual-motor integration awareness (the pP1), as well as with an increase of the late frontal negativity (the pN2), possibly reflecting an effort by the insula to recover and/or complete the most correct sensory-motor representation. In both occlusions, a decrease in the pP2 may reflect an impairment of decisional processes upon action execution following sensory evidence accumulation. Enhanced amplitude of the P3 and the pN2 components were found in more experienced players, suggesting a greater allocation of resources in the process connecting sensory encoding and response execution, and sensory-motor representation.     

The supplementary motor area in motor and perceptual time processing: fMRI studies

The neural bases of timing mechanisms in the second-to-minute range are currently investigated using multidisciplinary approaches. This paper documents the involvement of the supplementary motor area (SMA) in the encoding of target durations by reporting convergent fMRI data from motor and perceptual timing tasks. Event-related fMRI was used in two temporal procedures, involving (1) the production of an accurate interval as compared to an accurate force, and (2) a dual-task of time and colour discrimination with parametric manipulation of the level of attention attributed to each parameter. The first study revealed greater activation of the SMA proper in skilful control of time compared to force. The second showed that increasing attentional allocation to time increased activity in a cortico-striatal network including the pre-SMA (in contrast with the occipital cortex for increasing attention to colour). Further, the SMA proper was sensitive to the attentional modulation cued prior to the time processing period. Taken together, these data and related literature suggest that the SMA plays a key role in time processing as part of the striato-cortical pathway previously identified by animal studies, human neuropsychology and neuroimaging.     

Evaluation of two methods of prompting drivers to use specific exits on conflicts between vehicles at the critical exit

The Florida Department of Transportation used a series of changeable-message signs that functioned as freeway guide signs to divert traffic to Universal Theme Park via one of two eastbound exits based on traffic congestion at the first of the two exits. An examination of crashes along the entire route indicated a statistically significant increase in crashes at the first eastbound exit following the actuation of the system. Furthermore, all of the crashes occurred in close proximity to the exit gore (the crosshatched area at exits that drivers are not supposed to enter or traverse) at the first exit. In Experiment 1, behavioral data were collected using an alternating treatments design. These data revealed that reassigning the exit signs was effective in producing a change in the percentage of drivers using each of the two exits. These data also showed that the reassignment of the theme park exit was associated with an increase in the percentage of motor vehicle conflicts that consisted of vehicles cutting across the exit gore. An analysis revealed that the method used for switching the designated or active theme park exit on the series of changeable-message signs led to the presentation of conflicting messages to some motorists, thus resulting in erratic driving behavior (cutting across the exit gore). In Experiment 2, the treatment evaluated the use of a phased method of switching the designated theme park exit to eliminate the delivery of conflicting messages. The new method for switching the designated theme park exit was not associated with an increase in motorists cutting across the exit gore.     

A double-dissociation in infants' representations of object arrays

Previous studies show that infants can compute either the total continuous extent (e.g. Clearfield, M.W., & Mix, K.S. (1999). Number versus contour length in infants' discrimination of small visual sets. Psychological Science, 10(5), 408-411; Feigenson, L., & Carey, S. (2003). Tracking individuals via object-files: evidence from infants' manual search. Developmental Science, 6, 568-584) or the numerosity (Feigenson, L., & Carey, S. (2003). Tracking individuals via object-files: evidence from infants' manual search. Developmental Science, 6, 568-584) of small object arrays. The present experiments asked whether infants can compute both extent and number over a given array. Experiment 1 used a habituation procedure to show that 7-month-old infants can compute numerosity when the objects in the array contrast in color, pattern, and texture. Experiment 2 revealed that, with these heterogeneous arrays, infants no longer represent the array's total continuous extent. Since previous work shows that infants compute continuous extent but not numerosity when objects have identical rather than contrasting properties, these results form a double dissociation. Infants computed number but not extent over representations of contrasting objects, and computed extent but not number over representations of identical objects.     

The Neural Basis of Motor-Skill Learning

Recent work indicates that motor-skill learning is supported by four processes: a strategic process that selects new goals of what to change in the environment, a perceptual-motor integration process that adjusts to new relationships between environmental stimuli and the appropriate motor response, a sequencing process that learns sequences of motor acts, and a dynamic process that learns new patterns of muscle activations. These four processes can operate in one of two modes: an unconscious mode, in which one is aware only of the goal of the movement, or a conscious mode, in which one consciously controls detailed aspects of the movement. This article provides an overview of these four processes and two modes, and describes their neural bases.     

Methylphenidate Does Not Modify the Impact of Response Frequency or Stimulus Sequence on Performance and Event-Related Potentials of Children with Attention Deficit Hyperactivity Disorder

Twenty-six children with attention deficit/hyperactivity disorder (ADHD) participated in a double-blind trial consisting of 2 consecutive weeks each of placebo and methylphenidate (M = 26.92 mg/day = 0.78 mg/kg/day). As expected, stimulant therapy resulted in moderate weight loss, increased somatic complaints, and teacher and parent reports of reduced inattentiveness, aggression, and oppositionality. In both phases of the trial, patients were tested in a choice reaction time task assessing two aspects of the task that presumably affect response selection: response frequency (ratio of targets/nontargets = 25/75 vs. 50/50) and stimulus sequence (alternations vs. repetitions). Both manipulations yielded expected results on performance and event-related potentials (ERPs). Stimulant treatment increased accuracy and speed among younger children and curtailed variability of reaction time for the sample as a whole. However, methylphenidate did not affect ERPs. In combination, the results imply that the enhancement of performance by methylphenidate does not involve the demands of response selection examined in this study.     

短时动作记忆的容量和精确度与动作学习的关系

该研究采用实验室实验法,被试自我报告分析及调查访问法,以三个年龄（１０岁、１４岁、１８岁）组学生及专项运动员为实验对象,揭示短时动作记忆的容量和精确度及其与动作学习指数的关系。结果表明：（１）被试的短时动作记忆容量为“５±２”,短时动作记忆的容量与动作学习的练习次数相联系;短时动作记忆的精确度与第一次动作练习的准确度相联系。（２）短时动作记忆的容量有随年龄增长而递增的趋势。（３）运动员与非运动员被试对于同类动作学习的练习次数存在显著性差异。     

Teacher rated problems and school ability tests in relation to preschool problems and parents'' health information at school start. A study of first-graders

The reliability of assessments at four and six years of age in identifying teacher rated problems in behaviour, concentration, motor skill and school achievement was investigated in a study of first-graders. Relationships between preschool data and school ability tests, and between parents' information at school start and teacher ratings were also studied. Problems noted in preschool and school were often present in more than one area. Multiple problems at four and six years were strong predictors of later school problems, but preschool assessments of separate areas could not in general predict problems in corresponding areas in school. However, cross situational concentration deficits at the age of six did reliably identify concentration problems in the first grade, at the age of seven.     

Another look at “tummy time” for primary plagiocephaly prevention and motor development

It is three decades since it was recommended that infants sleep on the back to reduce risk of sudden unexpected infant death (SUID). The SUID prevention program is known as “back to sleep” or “safe sleeping”, and this initiative is not questioned. Sleeping on the back is associated with, but not the cause of, the development of infant positional plagiocephaly, also known as deformational or a non-synostotic misshapen head when the skull sutures are open, not fused. This paper provides a synthesis of the history and impact of positional plagiocephaly. It includes a scoping review of plagiocephaly prevention facilitating motor development and reveals few articles on primary prevention which aims to prevent it developing in the first place. It is concerning that preschool-aged children with a history of infant plagiocephaly continued to receive lower developmental scores, particularly in motor development, than unaffected controls, and this may be a marker of developmental delay. Tummy-time (prone) for play is the mainstay of plagiocephaly prevention advice to minimize development of plagiocephaly and to facilitate infant motor development, particularly head control. While tummy-time has shown benefit for infant development, there is limited evidence of its effectiveness in preventing plagiocephaly and some evidence that it promotes only prone-specific motor skills. Most of the published literature is concerned with treatment post-diagnosis, in the form of reviews, or clinical notes. There is a plethora of opinion articles reinforcing tummy-time from birth for plagiocephaly prevention. The review shows that there are gaps in advice for early infant development of head control. An accepted test of head control in infants is “pull to sit” from supine which demonstrates antigravity strength of the neck flexors and coordination of the head and neck when the infant is drawn to sit from supine. This motor skill was cited as achievable by 4 months in the earliest paper on plagiocephaly in 1996. Physical therapists and others should revisit the mechanism of early infant head control development against gravity, particularly antigravity head, neck and trunk coordinated flexion movement in supine, as there has been little attention to early facilitation of this motor skill as a plagiocephaly prevention strategy. This may be achieved by considering “face time” as well as tummy time for primary prevention of plagiocephaly.     

Unweighting infants reveals hidden motor skills

We investigated the role of rate limiting factors in development using walking as a model system. The achievement of bipedal posture and locomotion are among the most significant achievements in an infant's first year, with poor balance and weak muscles long proposed as the rate limiting factors. Compensating for either may reveal upright motor skill that has not yet emerged in the infant's natural repertoire. To probe this question, we unweighted prewalking infants and measured their performance in various standing and walking behaviors while unweighted compared to baseline. Our secondary objective was to determine if the influence of unweighting was related to infants’ locomotor experience. Infants stood unsupported for longer durations with 20% or 40% unweighting. Infants took more independent steps and more steps with one hand held with 40% unweighting. No differences in transition to/from standing were observed. Locomotor experience was related to the influence of unweighting during cruising and walking with a push toy. This is the first report of more advanced motor skills—longer periods of unsupported standing and the emergence of independent walking—revealed by unweighting infants. We interpret our observations to suggest that the refinement of motor control needed to support bipedal posture and locomotion precedes the functional emergence of these skills in infants. In other words, the musculoskeletal components required for walking are slower to develop than the neurological factors – and consequently may be the rate limiters. We further suggest that training regimens including unweighting should be explored in infants with motor delays.