Dopamine regulation of human speech and bird song: a critical review

To understand the neural basis of human speech control, extensive research has been done using a variety of methodologies in a range of experimental models. Nevertheless, several critical questions about learned vocal motor control still remain open. One of them is the mechanism(s) by which neurotransmitters, such as dopamine, modulate speech and song production. In this review, we bring together the two fields of investigations of dopamine action on voice control in humans and songbirds, who share similar behavioral and neural mechanisms for speech and song production. While human studies investigating the role of dopamine in speech control are limited to reports in neurological patients, research on dopaminergic modulation of bird song control has recently expanded our views on how this system might be organized. We discuss the parallels between bird song and human speech from the perspective of dopaminergic control as well as outline important differences between these species.     

Reinforcing saccadic amplitude variability

Saccadic endpoint variability is often viewed as the outcome of neural noise occurring during sensorimotor processing. However, part of this variability might result from operant learning. We tested this hypothesis by reinforcing dispersions of saccadic amplitude distributions, while maintaining constant their medians. In a first experiment we reinforced the least frequent saccadic amplitudes to increase variability, and then reinforced the central part of the amplitude distributions to reduce variability. The target was placed at a constant distance from the fovea after the saccade to maintain the postsaccadic visual signal constant and an auditory reinforcement was delivered depending on saccadic amplitude. The second experiment tested the effects of the contingency. We reinforced high levels of variability in 4 participants, whereas 4 other participants were assigned to a yoked control group. On average, saccadic amplitude standard deviations were doubled while the medians remained mostly unchanged in the experimental participants in both experiments, and variability returned to baseline level when low variability was reinforced. In the control group no consistent changes in amplitude distributions were observed. These results, showing that variability can be reinforced, challenge the idea of a stochastic neural noise. We instead propose that selection processes constrain saccadic amplitude distributions.     

Haptics in teaching handwriting: the role of perceptual and visuo-motor skills

Two studies were carried out in order to better understand the role of perceptual and visuo-motor skills in handwriting. Two training programs, visual-haptic (VH) and visual (V), were compared which differed in the way children explored the letters. The results revealed that improvements of VH training on letter recognition and handwriting quality were higher than improvements after V training. We suppose that VH training was more efficient because it improved both perceptual and visuo-motor skills. In the second experiment, in order to investigate the part of each component, we assessed the link between visuo-motor skills, perceptual skills and handwriting. The results showed that only the visuo-motor tasks predict handwriting copying performance. These results are discussed in relation to the respective roles of the perceptual and visuo-motor skills on letter shape learning and handwriting movement execution.     

睡眠对知觉与动作序列内隐学习离线巩固效应的影响

离线阶段发生的学习被称为离线巩固, 即在最初获得知识之后, 即使没有额外的练习, 其记忆痕迹也会保持稳定或提高。有研究初步探究了睡眠对知觉和动作序列内隐学习离线巩固的影响, 然而, 这些研究未能实现知觉序列与动作序列的完全分离, 序列类型是否调节睡眠对内隐序列学习离线巩固的影响仍需进一步探讨。此外, 既往外显学习的研究发现相对于简单的序列, 复杂的序列更容易从睡眠中获益, 表现出基于睡眠的离线巩固效应。睡眠对知觉序列与动作序列内隐学习离线巩固的影响是否会受到序列复杂程度的调节尚不明确。为此, 本研究在完全分离知觉序列和动作序列的情况下, 通过3个实验操纵序列的长度及结构, 设置3种不同复杂程度的序列规则, 考察了这一问题。结果发现, 对于动作序列, 序列规则复杂程度较低时, 无论是否经过睡眠都会发生离线巩固效应, 而当动作序列规则较为复杂时, 只有经历睡眠才会引起离线巩固效应; 对于知觉序列, 无论何种难易程度的规则, 均未发生离线巩固效应。上述结果表明内隐序列知识基于睡眠的离线巩固会受到序列类型及序列复杂程度的调节, 这为内隐学习的离线巩固争论提供了新的视角。     

抽象动词的具身表征：运动特征的影响

本研究使用具身行为范式—动作-句子相符效应（ACE）探讨了动词运动特征在抽象动词具身表征中的作用。实验1验证ACE在考察感觉运动系统参与双音节动词表征问题上的可行性,结果在具体动词中得到了ACE。实验2以不同运动特征值的抽象动词为材料,在高运动抽象动词中得到了ACE,但在低运动抽象动词中未发现ACE;且ACE大小与运动特征评分显著相关。结果证明了感觉运动系统在抽象动词表征中的参与,支持抽象概念的具身表征观点。     

Investigating the dose-response relationship between motor imagery and motor recovery of upper-limb impairment and function in chronic stroke: A scoping review

The recovery of upper-limb impairment and dysfunction post-stroke is often incomplete owing to the limited time in therapy focused on upper-limb recovery and the severity of the impairment. In these cases, motor imagery (MI) may be used as a precursor to physical therapies to initiate rehabilitation early on when it would be otherwise impossible to engage in therapy, as well as to increase the dose of therapy when MI is used in adjunct to physical therapy. While previous reviews have shown MI to be effective as a therapeutic option, disparity in findings exists, with some studies suggesting MI is not an effective treatment for post-stroke impairment and dysfunction. One factor contributing to these findings is inconsistency in the dose of MI applied. To explore the relationship between MI dose and recovery, a scoping review of MI literature as a treatment for adult survivors of stroke with chronic upper-limb motor deficit was performed. Embase, Medline and CINHAL databases were searched for articles related to MI and stroke. Following a two-phase review process, 21 papers were included, and data related to treatment dose and measures of impairment and function were extracted. Effect sizes were calculated to investigate the effect of dosage on motor recovery. Findings showed a high degree of variability in dosage regimens across studies, with no clear pattern for the effect of dose on outcome. The present review highlights the gaps in MI literature, including variables that contribute to the dose-response relationship, that future studies should consider when implementing MI.     

Anxiety and speaking in people who stutter: An investigation using the emotional Stroop task

People with anxiety disorders show an attentional bias towards threat or negative emotion words. This exploratory study examined whether people who stutter (PWS), who can be anxious when speaking, show similar bias and whether reactions to threat words also influence speech motor planning and execution. Comparisons were made between 31 PWS and 31 fluent controls in a modified emotional Stroop task where, depending on a visual cue, participants named the colour of threat and neutral words at either a normal or fast articulation rate. In a manual version of the same task participants pressed the corresponding colour button with either a long or short duration. PWS but not controls were slower to respond to threat words than neutral words, however, this emotionality effect was only evident for verbal responding. Emotionality did not interact with speech rate, but the size of the emotionality effect among PWS did correlate with frequency of stuttering. Results suggest PWS show an attentional bias to threat words similar to that found in people with anxiety disorder. In addition, this bias appears to be contingent on engaging the speech production system as a response modality. No evidence was found to indicate that emotional reactivity during the Stroop task constrains or destabilises, perhaps via arousal mechanisms, speech motor adjustment or execution for PWS.Educational objectives: The reader will be able to: (1) explain the importance of cognitive aspects of anxiety, such as attentional biases, in the possible cause and/or maintenance of anxiety in people who stutter, (2) explain how the emotional Stroop task can be used as a measure of attentional bias to threat information, and (3) evaluate the findings with respect to the relationship between attentional bias to threat information and speech production in people who stutter.     

反馈类型和反馈时间对动作技能获得的影响

基于简单直线运动任务和复杂曲线追踪任务,在运动技能获得阶段考察不同反馈类型和反馈时间对操作绩效的影响。结果发现,在复杂曲线轨迹追踪任务中,接受运动轨迹反馈的被试组比接受偏差数值反馈组的成绩更好;即时反馈和延迟反馈组的操作绩效间没有显著差异。在简单直线运动任务中,提供落点偏差的图形反馈组成绩始终优于提供“近/远”信息的文本反馈组;在练习初期,即时反馈组成绩更好。说明,反馈信息的具体-抽象程度影响被试运动技能获得,提供具体直观的轨迹/图形反馈利于运动技能获得;反馈时间对运动技能的影响因任务难度而异。