MOTOR PREPARATION,MOTOR EXECUTION,ATTENTION, AND EXECUTIVE FUNCTIONS IN ATTENTION DEFICIT/HYPERACTIVITY DISORDER (ADHD)

Attention and executive functions were investigated in medicated and unmedicated children with ADHD combined type using a novel selective reaching task. This task involved responding as rapidly as possible to a target while at times having to ignore a distractor. Results indicated that unmedicated children with ADHD showed slow and inaccurate responding. Slow responding reflected problems at the stage of movement preparation but not movement execution. An attentional impairment, rather than a motor planning problem per se, appeared to underlie the slow movement preparation. Inaccurate responding reflected problems with response inhibition and selective attention, impulsivity, set-shifting, and difficulties in maintaining vigilance. Although medicated children with ADHD did not show slow movement preparation, they did show some response inaccuracy, resulting especially from impulsive responding.These findings suggest that ADHD is characterized by slow motor preparation (but not motor execution), and deficits in selective attention, vigilance, and executive functions. Preliminary results suggest that stimulant medication may resolve some of these motor, attentional and executive function deficits.     

White-matter microstructure and language lateralization in left-handers: A whole-brain MRI analysis

Most people are left-hemisphere dominant for language. However the neuroanatomy of language lateralization is not fully understood. By combining functional magnetic resonance imaging (fMRI) and diffusion tensor imaging (DTI), we studied whether language lateralization is associated with cerebral white-matter (WM) microstructure. Sixteen healthy, left-handed women aged 20–25 were included in the study. Left-handers were targeted in order to increase the chances of involving subjects with atypical language lateralization. Language lateralization was determined by fMRI using a verbal fluency paradigm. Tract-based spatial statistics analysis of DTI data was applied to test for WM microstructural correlates of language lateralization across the whole brain. Fractional anisotropy and mean diffusivity were used as indicators of WM microstructural organization. Right-hemispheric language dominance was associated with reduced microstructural integrity of the left superior longitudinal fasciculus and left-sided parietal lobe WM. In left-handed women, reduced integrity of the left-sided language related tracts may be closely linked to the development of right hemispheric language dominance. Our results may offer new insights into language lateralization and structure–function relationships in human language system.     

基于直线临摹的ADHD儿童眼手协调能力研究

ADHD儿童在精细动作方面通常伴随眼手协调运动障碍。以往采用的研究方法多为定性研究,且未在ADHD儿童的运动协调性与同龄正常儿童的差异上得出统一结论。本研究针对精细动作中眼手协调能力进行定量分析。实验要求被试在计算机触摸屏上分别临摹水平线、垂直线和斜线,通过记录临摹直线与呈现直线的偏差程度和拐点数,以分析ADHD儿童眼手协调能力与正常儿童之间的差异。结果表明,ADHD儿童在眼手协调和空间知觉能力上与正常儿童存在显著性差异。此外,本研究表明,改进的定量方法具有良好的可行性。     

Relationships between non-pathological dream-enactment and mirror behaviors

Dream-enacting behaviors (DEBs) are behavioral expressions of forceful dream images often occurring during sleep-to-wakefulness transitions. We propose that DEBs reflect brain activity underlying social cognition, in particular, motor-affective resonance generated by the mirror neuron system. We developed a Mirror Behavior Questionnaire (MBQ) to assess some dimensions of mirror behaviors and investigated relationships between MBQ scores and DEBs in a large of university undergraduate cohort. MBQ scores were normally distributed and described by a four-factor structure (Empathy/Emotional Contagion, BehavioralImitation, Sleepiness/Anger Contagion, Motor Skill Imitation). DEB scores correlated positively with MBQ total and factor scores even with social desirability, somnambulism and somniloquy controlled. Emotion-specific DEB items correlated with corresponding emotion-specific MBQ items, especially crying and smiling. Results provide preliminary evidence for cross-state relationships between propensities for dream-enacting and mirror behaviors—especially behaviors involving motor-affective resonance—and our suggestion that motor-affective resonance mediates dream-enactment imagery during sleep and emotional empathy during waking.     

Possibilities and limits of mind-reading: A neurophilosophical perspective

Access to other minds once presupposed other individuals’ expressions and narrations. Today, several methods have been developed which can measure brain states relevant for assessments of mental states without 1st person overt external behavior or speech. Functional magnetic resonance imaging and trace conditioning are used clinically to identify patterns of activity in the brain that suggest the presence of consciousness in people suffering from severe consciousness disorders and methods to communicate cerebrally with patients who are motorically unable to communicate. The techniques are also used non-clinically to access subjective awareness in adults and infants. In this article we inspect technical and theoretical limits on brain–machine interface access to other minds. We argue that these techniques hold promises of important medical breakthroughs, open up new vistas of communication, and of understanding the infant mind. Yet they also give rise to ethical concerns, notably misuse as a consequence of hypes and misinterpretations.     

Effects of test anxiety on motor learning: The processing efficiency hypothesis

Abstract

The hypothesis that, under test (stress) conditions, high trait-anxious individuals invest extra processing resources to reach motor learning levels similar to those of low-anxious individuals was investigated. A transfer procedure (practice trial, rest interval, and transfer trial) was employed to analyse motor learning effects. In Experiment 1, a secondary task (click detection) was used to measure the extra processing resources expenditure on motor learning during the practice trial. Neither motor performance in the transfer trial nor secondary task performance differed as a function of test condition or anxiety trait. A critical analysis of the secondary task paradigm suggested that it was not sensitive enough to reflect the amount of processing capacity expended on the primary motor tasks. In Experiment 2, subjects performed a loading task (verbal shadowing of sentences) concurrently with the motor tasks during the practice trial to prevent extra resources from being allocated to motor learning. Results showed that anxiety trait was associated to performance time increments on the high-demanding motor tasks in the transfer trial. A plausible explanation is that anxiety impairs learning because it reduces the efficiency of processing. An alternative interpretation, concerning an ability deficit of high trait-anxious individuals, is discussed.     

Objective Evaluation of Performance Stress in Musicians With Focal Hand Dystonia: A Case Series

Five musicians suffering from focal dystonia participated in a pilot study that examined the feasibility of an experimental protocol designed to assess musicians' motor performance under stress. Electrocardiography, free cortisol levels, and subjective assessments were used to monitor alterations of the hypothalamic-pituitary-adrenal axis. As measures of motor outcome, temporal variability of finger movements and muscular cocontraction of the wrist flexor and extensor were assessed. Findings suggest that the specific experimental design could be successfully applied. Several methodological issues such as carryover effects, the use of free cortisol, the inclusion of a double baseline, and the classification of dystonic patients into stress responders and nonresponders are analyzed and discussed.     

Individualized Challenge Point Practice as a Method to Aid Motor Sequence Learning

We conducted two studies to investigate if and how: (1) the rate of skill acquisition was related to motor performance at retention of a serial RT task (Study 1); and (2) whether rate of skill acquisition and baseline performance could be used to design schedules of practice related to contextual interference (CI) to enhance motor learning (Study 2). In Study 1, a slower rate of skill acquisition of repeating sequences in practice was related to faster response times at retention. Based on performance in Study 1, three levels of individualized CI were created for Study 2. Compared to low and moderate levels of CI, the higher CI practice condition led to faster response times in retention. We conclude that an individualized ‘challenge point’, which generates high CI enhances motor learning by optimizing challenge.