Proprioceptive control of goal-directed movements in man, studied by means of vibratory muscle tendon stimulation

The purpose of this study was to investigate the role of propriomuscular feedback in the control of pluriarticular pointing movements, performed without visual feedback toward visual targets. The proprioceptive inputs were distorted during movements by applying vibration to the distal tendon of the biceps muscle. Various movement and vibration durations were imposed. The results show that vibration affects the spatial outcome of the movements. The effects of vibration were movement time-independent when the durations were shorter than 450 ms and became movement time-dependent with longer durations. Moreover, the effects of vibration became more marked when a short vibration was applied at the end rather than at the beginning of a slow movement. These studies suggest that at least two types of proprioceptive control loops may be involved in correcting this kind of movement, depending on the execution time. In slow movements, the final phase might be a privileged period for on-line, propriomuscular-based corrections. Lastly, it emerged that the regulation of a goal-directed movement on the basis of proprioceptive feedback processing can take place within at most 200 ms.     

Cathodal tDCS of the Left Posterior Parietal Cortex Increases Proprioceptive Drift

In aiming movements the limb position drifts away from the defined target after some trials without visual feedback, a phenomenon defined as proprioceptive drift (PD). There are no studies investigating the association between the posterior parietal cortex (PPC) and PD in aiming movements. Therefore, cathodal and sham transcranial direct current stimulation (tDCS) were applied to the left PPC concomitantly with the performance of movements with or without vision. Cathodal tDCS applied without vision produced a higher level of PD and higher rates of drift accumulation while it decreased peak velocity and maintained the number of error corrections, not affecting movement amplitude. The proprioceptive information seems to produce an effective reference to movement, but with PPC stimulation it causes a negative impact on position.     

Development of forward models for hand localization and movement control in 6- to 10-year-old children

An active kinesthetic-to-visual matching task was performed by 15 children aged 5-10 years and five young adults. The task required the participants to locate the target visually while performing center-out drawing movements to the located visual targets in the absence of visual feedback of hand/pen motion. Movement time (MT), terminal end-point position error (EPE), and initial directional error (IDE) were measured. The general finding is that the end-point error variability, representing the joint localization probability distributions for proprioceptive localization of the hand and visual localization of the target, was largest for the youngest children, but did not differ from one another for the older age groups. The localization distributions, as characterized by principal component analysis, showed that both errors in extent and direction were significantly larger in the youngest children. These error distributions could not be accounted for by initial localization errors prior to movement onset in the children. It is likely that at least some portion of the increased movement variability seen during sensorimotor development in young children can be attributed not only to immature control mechanisms per se, but also to partial, not yet stable, forward representations for hand localization which are used for movement perception, planning, and control.     

Repetitive pointing to remembered proprioceptive targets improves 3D hand positioning accuracy

Repetitive pointing movements to remembered proprioceptive targets were investigated to determine whether dynamic proprioception could be used to modify the initial sensorimotor conditions associated with an active definition of the target position. Twelve blindfolded subjects used proprioception to reproduce a self-selected target position as accurately as possible. Ten repetitions for each limb were completed using overhead and scapular plane pointing tasks. A 3D optical tracking system determined hand trajectory start and endpoint positions for each repetition. These positions quantified three-dimensional pointing errors relative to the target position and the initial and preceding movement repetitions, as well as changes in movement direction and extent. Target position and cumulative start position errors were significantly greater than the corresponding preceding movement (inter-repetition) errors, and increased as the trial progressed. In contrast, hand trajectory start and endpoint inter-repetition errors decreased significantly with repeated task performance, as did movement extent, although it was consistently underestimated for each repetition. Pointing direction remained constant, except for the angle of elevation for scapular plane pointing, which consistently decreased throughout the trial. The results suggest that the initial conditions prescribed by actively defining a proprioceptive target were subsequently modified by dynamic proprioception, such that movement reproduction capability improved with repeated task performance.     

Effects of movement duration and visual feedback on visual and proprioceptive components of prism adaptation

While looking through laterally displacing prisms, subjects pointed sagittally 80 times at an objectively straight-ahead target, completing a reciprocal out-and-back pointing movement ever 1, 3, or 6 s. Visual feedback was available early in the pointing movement or only late at the end of the movement. Aftereffect measures of adaptive shift (obtained after every 10 pointing trials) showed adaptive change only in limb position sense (i.e., proprioceptive adaptation) when movement duration was 1 s, regardless of visual feedback condition; but as movement duration increased, adaptive change in the eye position sense (i.e., visual adaptation) increased while proprioceptive adaptation decreased, especially for the late visual feedback condition. Regardless of visual feedback condition, proprioceptive adaptation showed the maximal rate of growth with the 1-s movement duration, whereas visual adaptation showed maximal growth with the 6-s movement duration. These results provide additional support for a model of adaptive spatial mapping in which the direction of strategically flexible coordination (guidance) between eye and limb (and consequently the locus of adaptive spatial mapping) is jointly determined by movement duration and timing of visual feedback. An additional effect of movement duration is to determine the rate of discordant inputs. Maximal growth of adaptation occurs when the input rate matches the response time of the spatial mapping function.     

Effects of Movement Duration and Visual Feedback on Visual and Proprioceptive Components of Prism Adaptation

While looking through laterally displacing prisms, subjects pointed sagittally 80 times at an objectively straight-ahead target, completing a reciprocal out-and-back pointing movement every 1, 3, or 6 s. Visual feedback was available early in the pointing movement or only late at the end of movement. Aftereffect measures of adaptive shift (obtained after every 10 pointing trials) showed adaptive change only in limb position sense (i.e., proprioceptive adaptation) when movement duration was 1 s, regardless of visual feedback condition; but as movement duration increased, adaptive change in the eye position sense (i.e., visual adaptation) increased while proprioceptive adaptation decreased, especially for the late visual feedback condition. Regardless of visual feedback condition, proprioceptive adaptation showed the maximal rate of growth with the 1-s movement duration, whereas visual adaptation showed maximal growth with the 6-s movement duration. These results provide additional support for a model of adaptive spatial mapping in which the direction of strategically flexible coordination (guidance) between eye and limb (and consequently the locus of adaptive spatial mapping) is jointly determined by movement duration and timing of visual feedback. An additional effect of movement duration is to determine the rate of discordant inputs. Maximal growth of adaptation occurs when the input rate matches the response time of the spatial mapping function.     

The attentional cost of amplitude and directional requirements when pointing to targets

The aim of this study was to investigate the comparative cost of accuracy constraints in direction or amplitude for movement regulation. The attentional cost is operationally defined as the amount of disturbance created in a secondary task by the simultaneous execution of a pointing task in direction or amplitude. The cost is expressed in terms of modifications in response to a secondary task, consisting of a foot-pedal release in response to an auditory stimulus (probe). The probe was introduced during the programming portion or the first, middle, or last portion of the pointing movement. The independent variables were the requirements of the task: direction or amplitude, and the moments of occurrence of the probe. Subjects were submitted to eight experimental conditions: (1) simple foot reaction time to a buzzer; (2) single directional task; (3) single amplitude task; (4) dual directional task (i.e. directional task with probe); (5) dual amplitude task (i.e. amplitude task with probe); (6) retest of foot simple reaction time; (7) retest of single directional task; and (8) retest of single amplitude task. Regulation in direction was more attention-demanding than regulation in distance in terms of programming. During pointing in amplitude, probe RT increased monotonically from start to end of movement execution, whereas directional pointing did not lead to any significant probe RT changes. These results emphasize the specific attentional loads for directional and amplitude pointing tasks, hence the involvement of different central nervous system mechanisms for the programming and regulation of the directional and amplitude parameters of pointing movements.     

An internal focus of attention is optimal when congruent with afferent proprioceptive task information

Whilst benefits of an external focus are shown to govern several characteristics of skill execution, specificity theory indicates that sources of afferent information most useful to performance execution are typically prioritised during processing.ObjectivesWe investigated whether an internal focus facilitates performance when pertinent afferent information is proprioceptive in nature and congruent with attentional focus. We also considered whether the mechanisms behind attentional focus differences are attributable to planning processes or online motor control.DesignExperiments 1 and 2 adopted a randomised design, whilst experiment 3 used a repeated measures approach.MethodIn Experiment 1 we investigated movement variability as a measure of planning and error correction under external and internal focus conditions in an aiming task. Experiment 2 removed visual information to increase pertinence of proprioceptive feedback for movement execution and Experiment 3 adopted a leg-extension task, where proprioceptive salience was enhanced using an ankle weight. We hypothesised that this would increase congruency between internal focus instructions and movement production.ResultsExperiments 1 and 2 revealed reduced amplitude errors under an internal focus whilst Experiment 3 showed similar findings with the addition of lower EMG activity when adopting an internal focus. Movement variability findings were indicative of enhanced planning.ConclusionsWhen pertinence of proprioceptive information was amplified, benefits of an internal focus were more pronounced and performance was higher. Participants were better able to focus on movement characteristics to process proprioceptive feedback: something not afforded under an external focus. This raises doubts regarding the rigidity of the constrained action hypothesis.     

Perceptual skills of children with developmental coordination disorder

The aim of this study was to investigate whether children with a Developmental Coordination Disorder (DCD) experience problems in the processing of visual, proprioceptive or tactile information. Different aspects of visual perception were tested with the Developmental Test of Visual Perception (DTVP-2), tactile perception was assessed with the Tactual Performance Test (TPT), and a manual pointing task was employed to measure the ability to use visual and proprioceptive information in goal-directed movements. Nineteen children with DCD and nineteen age and sex-matched controls participated in this study. Differences between groups were most pronounced in the subtests measuring visual-motor integration of the DTVP-2, and in two subtests measuring visual perception (visual closure and position in space). On average the children with DCD performed slightly below the norm for tactile perception, with only three children failing the norm. On the manual pointing task, children with DCD made inconsistent responses towards the targets in all three conditions (visual, visual-proprioceptive and proprioceptive condition). No significant differences between groups were found for absolute error. Inspection of the individual data revealed that only two children failed on the majority of perceptual tasks in the three modalities. Across tasks, no consistent pattern of deficits appeared, illustrating the heterogeneity of the problems of children with DCD.     

Adaptation to visual and proprioceptive rearrangement: Origin of the differential effectiveness of active and passive movements

In Experiment 1, subjects exposed to a discordance between the visual and ”proprioceptive” locations of external targets were found to exhibit aftereffects when later pointing without sight of their hands at visual targets. Aftereffects occur both when the discordance is introduced in the traditional fashion by displacing the visual locations of targets and when the proprioceptive locations of targets are displaced. These observations indicate that there is nothing unique about the visual rearrangement paradigm—the crucial factor determining whether adaptation will be elicited is the presence of a discordance in the positional information being conveyed over two different sensory modalities. In a second experiment, the effectiveness of active and passive movements in eliciting adaptation was studied using an experimental paradigm in which subjects were exposed to a systematic discordance between the visual and proprioceptive locations of external targets without ever being permitted sight of their hands; a superiority of active movements was observed, just as is usually found in visual rearrangement experiments in which sight of the hand is permitted. Evidence is presented that the failure of passive movements to elicit adaptation is related to a deterioration in accuracy of position sense information during passive limb movement.     

Orienting to targets by looking and pointing: Parallels and interactions in ocular and manual performance

Orienting to a target by looking and pointing is examined for parallels between the control of the two systems and interactions due to movement of the eyes and limb to the same target. Parallels appear early in orienting and may be due to common processing of spatial information for the ocular and manual systems. The eyes and limb both have shorter response latency to central visual and peripheral auditory targets. Each movement also has shorter latency and duration when the target presentation is short enough (200 msec) that no analysis of feedback of the target position is possible during the movement. Interactions appear at many stages of information processing for movement. Latency of ocular movement is much longer when the subject also points, and the eye and limb movement latencies are highly correlated for orienting to auditory targets. Final position of eyes and limb are significantly correlated only when target duration is short (200 msec). This illustrates that sensory information obtained before the movement begins is an important, but not the only, source of input about target position. Additional information that assists orienting may be passed from one system to another, since visual information gained by looking aided pointing to lights and proprioceptive information from the pointing hand seemed to assist the eyes in looking to sounds. Thus the production of this simple set of movements may be partly described by a cascade-type process of parallel analysis of spatial information for eye and hand control, but is also, later in the movement, assisted by cross-system interaction.     

Position Sense Dysfunction Affects Proximal and Distal Arm Joints in Children with Developmental Coordination Disorder

It is unclear, whether proprioceptive dysfunction in developmental coordination disorder (DCD) is localized affecting only specific joints or whether it is generalized affecting proximal and distal joints. Thus, this study assessed position sense acuity at the elbow and wrist in twenty children with DCD (age: 9–11 yrs.) using a joint position matching paradigm. Position sense bias (systematic error) at either joint was not significantly higher in DCD children when compared to typically developing children (TD). However, DCD children exhibited significantly lower position sense precision (random error) than TD children at both elbow and wrist. That is, response reliability to proprioceptive stimuli is altered in DCD. Our findings are consistent with a view that proprioceptive dysfunction in DCD is generalized in nature.     

Effects of Pointing Rate and Availability of Visual Feedback on Visual and Proprioceptive Components of Prism Adaptation

While looking through laterally displacing prisms, subjects pointed 60 times straight ahead of their nose at a rate of one complete movement every 2 or 3 s, with visual feedback available early in the pointing movement or delayed until the end of the movement. Sagittal pointing was paced such that movement speed covaried with pointing rate. Aftereffect measures (obtained after every 10 pointing trials) showed that when the limb became visible early in a pointing movement, proprioceptive adaptation was greater than visual, but when visual feedback was delayed until the end of the movement, the reverse was true. This effect occurred only with the 3-s pointing rate, however. With the 2-s pointing rate, adaptation was predominately proprioceptive in nature, regardless of feedback availability. Independent of the availability of visual feedback, visual adaptation developed more quickly with 3-s pointing, whereas proprioceptive adaptation developed more rapidly with 2-s pointing. These results are discussed in terms of a model of perceptual-motor organization in which the direction of coordinative (guidance) linkage between eye-head (visual) and hand-head (proprioceptive) systems (and consequently the locus of discordance registration and adaptive recalibration) is determined jointly by pointing rate and feedback availability. An additional effect of pointing rate is to determine the rate of discordant inputs. Maximal adaptive recalibration occurs when the input (pointing) rate matches the time constant of the adaptive encoder in the guided system.     

The effect of pre-movement delays on pointing accuracy in middle childhood.

In adults, the introduction of a pre-response delay has been shown to affect accuracy in pointing tasks while leaving accuracy in perceptual matching tasks unaffected. Here, we report on the effect of pre-movement delays on pointing accuracy in 6-10-year-old children. Children of this age group are of particular interest as their reliance on visual cues to monitor and correct their reaches appears to change during this period of development. Nineteen children were asked to point to the location of a target light after a delay of 0, 1, 2, or 4 s following target extinction. Performance was measured in two conditions: (i) open-loop, where the child reproduced the target locations in complete darkness, and (ii) with visual feedback, where information about hand position was available. Errors in the direction and in the amplitude of each reaching movement were recorded separately. The results show that temporal delay significantly affects the pointing movements of these children. Accuracy (mean) deteriorated after only 1 s whereas the precision (standard deviation) of the responses deteriorated after 4 s. Errors in amplitude, but not errors in direction, were reduced by the provision of visual feedback. Taken together, the findings suggest that amplitude and directional components of pointing in childhood utilise different sources of information, which differ in the extent to which temporal constraints operate.     

The effect of amplitude and accuracy requirements on movement time in children

The object of this study was to investigate how children control their movements, through- the analysis of Fitts' Law on subjects 5, 7, 9, and 11 yr of age. Children had to perform rapid alternative pointing movements between two targets, varying in width and distance (level of difficulty of the task). The analysis of movement time showed that, as children grow up, movement speed increased and was gradually less affected by the level of difficulty of a given task; moreover the respective effects of accuracy and amplitude requirements on movement time changed with age, resulting in distinct evolutive patterns. The results are thereby discussed in relation to the respective development of both programming and guiding components of movement in children. A few observations about ocular strategies during the task were also noted.     

Effects on prism adaptation of duration and timing of visual feedback during pointing

In two experiments, we investigated the effects of duration of visual feedback of the pointing limb and the time (early to late) in the movement when the limb first becomes visible (timing of visual feedback). Timing, rather than duration of visual feedback, proved to have the greater effect on the relative magnitude of visual and proprioceptive adaptation. Visual adaptation increased smoothly with feedback delay, but corresponding decreases in proprioceptive adaptation underwent an additional sharp change when feedback was delayed until about three-fourths of the way to the terminal limb position. These results are consistent with the idea that visual and proprioceptive adaptation are mediated by exclusive processes. Change in the limb position sense (i.e., proprioceptive adaptation) may be produced by visual guidance of the pointing limb, and view of the limb early in the pointing movement seems to be critical for such visual guidance. The limb may be ballistically released as it nears the terminal position, and, thereafter, any opportunity for visual guidance (i.e., view of the limb) is not effective. On the other hand, change in the eye position sense (i.e., visual adaptation) may be mediated by proprioceptive guidance of the eye; the eyes may track the imaged position of the nonvisible limb. Such proprioceptive guidance seems to be solely a function of the distance moved before the limb becomes visible.     

Experiencing the Cross-Sensory Error Signal During Movement Leads to Proprioceptive Recalibration

Abstract

Reaching to targets in a virtual reality environment with misaligned visual feedback of the hand results in changes in movements (visuomotor adaptation) and sense of felt hand position (proprioceptive recalibration). We asked if proprioceptive recalibration arises even when the misalignment between visual and proprioceptive estimates of hand position is only experienced during movement. Participants performed a “shooting task” through the targets with a cursor that was rotated 30° clockwise relative to hand motion. Results revealed that, following training on the shooting task, participants adapted their reaches to all targets by approximately 16° and recalibrated their sense of felt hand position by 8°. Thus, experiencing a sensory misalignment between visual and proprioceptive estimates of hand position during movement leads to proprioceptive recalibration.     

Vision,proprioception and corollary discharge in a movement recall test

Movement recall was investigated in relation to the sensory processes involved in a triangle drawing task.Forty subjects in two groups, one with and one without visual feedback, performed a recall task involving movements of their index finger. All subjects attended different experimental sessions in which (1) all proprioceptive feedback was eliminated by the ischaemic block technique, (2) muscle spindle feedback was distorted by vibration of the muscles and tendons involved in the movement, and (3) proprioceptive feedback was normal.Within each session subjects were required firstly to recall triangular movements made for them passively by the experimenter, and secondly, to recall movements they had made actively. Results indicated comparable accuracy in recall of active movements in all conditions, and a decrement in passive recall dependent on the availability of the alternative sources of feedback. The results indicated a process of integrated contribution of all inputs to the perception of movement; redundancy in information when all channels are available; and a role of corollary discharge in recall of movements.     

Effects on Prism Adaptation of Duration and Timing of Visual Feedback During Pointing

In two experiments, we investigated the effects of duration of visual feedback of the pointing limb and the time (early to late) in the movement when the limb first becomes visible (timing of visual feedback). Timing, rather than duration of visual feedback, proved to have the greater effect on the relative magnitude of visual and proprioceptive adaptation. Visual adaptation increased smoothly with feedback delay, but corresponding decreases in proprioceptive adaptation underwent an additional sharp change when feedback was delayed until about three-fourths of the way to the terminal limb position. These results are consistent with the idea that visual and proprioceptive adaptation are mediated by exclusive processes. Change in the limb position sense (i.e., proprioceptive adaptation) may be produced by visual guidance of the pointing limb, and view of the limb early in the pointing movement seems to be critical for such visual guidance. The limb may be ballistically “released“ as it nears the terminal position, and, thereafter, any opportunity for visual guidance (i.e., view of the limb) is not effective. On the other hand, change in the eye position sense (i.e., visual adaptation) may be mediated by proprioceptive guidance of the eye; the eyes may track the imaged position of the nonvisible limb. Such proprioceptive guidance seems to be solely a function of the distance moved before the limb becomes visible.     

Movement adaptations in 7- to 10-year-old typically developing children: evidence for a transition in feedback-based motor control

We used a modified double-step pointing task to study movement adaptations in 7- to 10-year-old typically developing children. We found that the majority (63%) were able to optimally adapt fast, goal-directed visually-guided movements to a late change in target location meeting the requirements of speed and accuracy. A minority (35%) failed to meet the requirement of accuracy resulting in a less optimal adaptation. The results showed that the ability to adapt movements optimally develops before the age of 7 years in typically developing children. Literature proposes a transition in development of motor control around the age of 8 years. The present results replicate and extend this by suggesting that this transition affects the later phases of fast, goal-directed visually-guided movements rather than the early phases, such as movement programming and acceleration. Finally, the results indicate that the optimally adapted movements were the result of a specific strategy in which a specific component of movement execution was slowed on all trials. This suggests that 7- to 10-year-old typically developing children have developed implicit knowledge about which movement components are the most efficient to adapt.