Proprioception and Motor Control in Parkinson's Disease

ABSTRACT

Parkinson's disease (PD) is a neurodegenerative disorder that leads to a progressive decline in motor function. Growing evidence indicates that PD patients also experience an array of sensory problems that negatively impact motor function. This is especially true for proprioceptive deficits, which profoundly degrade motor performance. This review specifically address the relation between proprioception and motor impairments in PD. It is structured around 4 themes: (a) It examines whether the sensitivity of kinaesthetic perception, which is based on proprioceptive inputs, is actually altered in PD. (b) It discusses whether failed processes of proprioceptive-motor integration are central to the motor problems in PD. (c) It presents recent findings focusing on the link between the proprioception and the balance problems in PD. And (d) it discusses the current state of knowledge of how levodopa medication and deep brain stimulation affect proprioceptive and motor function in PD. The authors conclude that a failure to evaluate and to map proprioceptive information onto voluntary and reflexive motor commands is an integral part of the observed motor symptoms in PD.     

Highs and Lows in Motor Control Development

Abstract

Motor control is classically described as relying on two components: anticipatory control (feedforward processing) and online control (feedback processing). Here we aimed to unveil the developmental steps of both feedback and feedforward control in 5–10 years old children, using a simple and ecological task. We manipulated object’s weight in a reach-to-displace paradigm. When the weight was known before lifting it, anticipatory processes were quantifiable during the reaching phase. Conversely, an unknown weight triggered online corrections during the displacing phase. Movement kinematics revealed that children anticipate this objet property as young as 5 y-o. This anticipation becomes adequate around 7 y-o and is paralleled by poor online corrections. This simple yet relevant paradigm should allow quantifying deviations from neurotypical patterns in disorders of motor control.     

Deliberate Control of Continuous Motor Performance

The authors examined the means by which people vary movement parameters to satisfy more than 1 constraint at a time in a repetitive motor task. The authors expected that when participants (N = 12) were simultaneously confronted with spatial and temporal constraints in an ellipse-drawing task, they would either exploit the intrinsic amplitude-frequency relationships or activate less natural control regimes to prioritize their movement goals. By focusing on local amplitude and frequency errors and parameter changes from 1 movement to the next, the authors distinguished parameter changes that reflected exploitation of biomechanics from those that required deliberate control. The findings demonstrated that at low movement speeds, participants can pursue multiple movement goals simultaneously; at higher speeds, their capacity to satisfy multiple task goals is reduced. The authors used a new method of inferring deliberate control from movement kinematics in the present study.     

Multisensory Information in the Control of Complex Motor Actions

ABSTRACT— For many of the complex motor actions we perform, perceptual information is available from several different senses including vision, touch, hearing, and the vestibular system. Here I discuss the use of multisensory information for the control of motor action in three particular domains: aviation, sports, and driving. It is shown that performers in these domains use information from multiple senses—frequently with beneficial effects on performance but sometimes with dangerous consequences. Applied psychologists have taken advantage of our natural tendency to integrate sensory information by designing multimodal displays that compensate for situations in which information from one or more of our senses is unreliable or is unattended due to distraction.     

Pupil Diameter May Reflect Motor Control and Learning

Non–luminance-mediated changes in pupil diameter have been used since the first studies by Darwin in 1872 as indicators of clinical, cognitive, and arousal states. However, the relation between processes involved in motor control and changes in pupil diameter remains largely unknown. Twenty participants attempted to compensate random walks of a cursor with a computer mouse to restrain its trajectory within a target circle while the authors recorded their pupil diameters. Two conditions allowed the authors to experimentally manipulate the motor and cognitive components of the task. First, the step size of the cursor's random walk was either large or small leading to 2 task difficulties (difficult or easy). Second, they instructed participants to imagine controlling the cursor by moving the mouse, but without actually moving it (task modality: imagined movement or real movement condition). Task difficulty and modality allowed the authors to show that pupil diameters reflect processes involved in motor control and in the processing of feedback, respectively. Furthermore, the authors also demonstrate that motor learning can be quantified by pupil size. This noninvasive approach provides a promising method for investigating not only motor control, but also motor imagery, a research field of growing importance in sports and rehabilitation.     

The Role of Visual Cues in Movement Control and Motor Memory

3 groups of 12 Ss performed an index finger letter-writing task with visual information but without kinesthetic cues (+V?K), followed immediately by repeating the same letters without vision (?V?K). All groups performed 6 test trials of + V?K, then ?V?K writing. Group 1 had no experience with the task prior to the test trials, Group 2 practiced the letters without vision with kinesthetic cues (?V+K), while Group 3 had visual and kinesthetic practice (+V+K). Visual cues efficiently guided performance in the absence of kinesthesis, and visual memory traces had a marked reinforcing effect. Further, learned reliance on kinesthetic cues was present even in +V?K performance, but reliance on visual cues did not develop.     

The Concept of Voluntary Motor Control in the Recent Neuroscientific Literature

Synthese - The concept of voluntary motor control(VMC) frequently appears in the neuroscientific literature, specifically in the context of cortically-mediated, intentional motor actions. For...     

The Effects of Brain Lateralization on Motor Control and Adaptation

ABSTRACT

Lateralization of mechanisms mediating functions such as language and perception is widely accepted as a fundamental feature of neural organization. Recent research has revealed that a similar organization exists for the control of motor actions, in that each brain hemisphere contributes unique control mechanisms to the movements of each arm. The authors review present research that addresses the nature of the control mechanisms that are lateralized to each hemisphere and how they impact motor adaptation and learning. In general, the studies suggest an enhanced role for the left hemisphere during adaptation, and the learning of new sequences and skills. The authors suggest that this specialization emerges from a left hemisphere specialization for predictive control—the ability to effectively plan and coordinate motor actions, possibly by optimizing certain cost functions. In contrast, right hemisphere circuits appear to be important for updating ongoing actions and stopping at a goal position, through modulation of sensorimotor stabilization mechanisms such as reflexes. The authors also propose that each brain hemisphere contributes its mechanism to the control of both arms. They also discuss the potential advantages of such a lateralized control system.     

论法家思想中的变法与定法

战国法家有变法和定法主张,它们是辩证的统一。这种辩证统一表现在以下两对概念的关系中:一是法的更改和确立;二是法的动和静。更改和确立是同一变法活动的两个环节,缺一不可;动和静则具有更为内在的意义,它们是更改和确立的根据,更改和确立则是它们的结果或目的。变法和定法是上述两对概念辩证统一关系的现实形态,与现代法律哲学所谓的法具有灵活性和稳定性的性质和表现是一致的,可以得到历史的印证。战国时期各国开展了确立成文法的变法运动,法的灵活性和稳定性的冲突也随之加剧,而这正是法家提出变法和定法主张的历史根源。     

The Effect of Practice on Human Performance in a Preview-Constrained Motor Control Task

This study examined the effect of short-term practice on the parameters of a linear model involving mean arm movement time as a function of Fitts’s index of difficulty (ID) variable and a preview-constraint ID variable. Significant (at the 2% level) interactions were found to exist between practice and the two ID variables indicating that the model parameters associated with these variables are both linear functions of practice time.     

Changes in Saccadic and Manual Motor Control After Ocular Smooth Pursuit Adaptive Modifications

The gain of ocular smooth pursuit responses can be adaptively modified under certain circumstances. Evidence that these modifications are caused, at least partly, by changes at a sensory level comes from the fact that subsequent manual tracking movements generated during visual fixation are also modified in a similar manner. The question addressed in the present experiment was whether the modifications are constrained specifically to responses such as these, which are driven by retinal image motion, or whether they can also influence movements that make use of retinal image position. This was accomplished by comparing manual and oculomotor responses to step changes in target position before and after smooth pursuit adaptation. The results showed that, as with manual tracking movements, these responses were also modified by the adaptive procedure, although to a lesser extent. In particular, following a 20-min period in which subjects (N = 4) were submitted to a procedure designed to increase the gain of the smooth pursuit system, manual step tracking movements and ocular saccades displayed larger amplitudes than those shown prior to the adaptation. In addition, these gain changes were accompanied by appropriate alterations in response kinematics. Taken together, these results suggest that the mechanisms responsible for adaptive modifications in the smooth pursuit system are also able to more generally influence the processing of visuospatial information. The possible neurophysiological substrate underlying these mechanisms is discussed.     

Emotion and Motor Control: Movement Attributes Following Affective Picture Processing

The authors investigated the impact of emotion on the performance of a square-tracing task after participants (N = 40) were exposed to pleasant (P), unpleasant (U), and neutral (N) pictures. Physiological and self-report measures indexed affective valence and arousal. In Experiment 1, greater error followed exposure to 4 consecutive U images than exposure to 4 consecutive P images. Speed of performance did not vary as a function of valence. In Experiment 2, participants viewed 1 slide per trial within a modified exposure protocol. Speed of performance varied as a function of valence; faster performance followed U relative to P stimuli. Accuracy of performance did not vary between conditions. Corresponding self-report and physiological measures generally corroborated previous evidence. Findings collectively indicated that the length of exposure to affective stimuli mediates speed and accuracy of motor performance; compared with P stimuli, U stimuli led to either increased error (short exposure) or increased speed (multiple exposures). The authors conclude that brief and extended exposures to affective pictures have direct behavioral consequences, and they discuss the implications of that finding.     

Increased Intrasubject Variability in Boys with ADHD Across Tests of Motor and Cognitive Control

Increased intrasubject variability (ISV), or short-term, within-person fluctuations in behavioral performance is consistently found in Attention-Deficit/Hyperactivity Disorder (ADHD). ADHD is also associated with impairments in motor control, particularly in boys. The results of the few studies that have examined variability in self-generated motor output in children with ADHD have been inconsistent. The current study examined variability in motor control during a finger sequencing task among boys with and without ADHD as well as the relationship between intrasubject variability during motor and cognitive control tasks. Changes in performance over the course of the task and associations with ADHD symptom domains were also examined to elucidate the nature of impaired motor control in children with ADHD. Fifty-one boys (ages 8 to 12 years) participated in the study, including 28 boys with ADHD and 23 typically developing (TD) boys. Participants completed a finger sequencing task and a Go/No-Go task providing multiple measures of response speed and variability. Boys with ADHD were slower and more variable in both intertap interval on the finger sequencing task and reaction time on the Go/No-Go task, with measures of speed and variability correlated across the two tasks. For the entire cohort, the only unique predictor of parent ratings of hyperactive-impulsive symptoms was variability in intertap interval during finger sequencing, whereas inattentive symptoms were only predicted by reaction time variability on the Go/No-Go task. These findings suggest that inefficient motor control is implicated in the pathophysiology of ADHD, particularly in regards to developmentally inappropriate levels of hyperactivity and impulsivity.