ABSTRACT
The goal of the current research was to establish the impact of mental fatigue on the contributions of explicit (i.e., conscious strategy) and implicit (unconscious) processes to visuomotor adaptation. Participants were divided into two groups, a Mental Fatigue (MF) group who completed a cognitively demanding 32-minute time load dual back task (TLDB), and a Control group who watched a documentary for a similar length of time. Following the TLDB task or documentary watching, participants trained to reach with a visuomotor distortion, such that cursor feedback was rotated 40º clockwise relative to hand motion. Explicit and implicit contributions to visuomotor adaptation were assessed following 3 blocks of 45 rotated reach training trials and again following a 20-minute rest. Levels of mental fatigue, as indicated on a self-report scale, increased significantly for the MF group following the TLDB task. The Control group did not display a similar increase in mental fatigue following the documentary watching. Results then revealed a decrease in visuomotor adaptation early in training for the MF group compared to the Control group, as well as decreased retention of visuomotor adaptation immediately following the 20-minute rest. Furthermore, correlational analyses revealed that greater levels of mental fatigue reported by participants in the MF group were associated with less explicit adaptation and greater implicit adaptation. Similar trends were not observed for the Control group. Taken together, the decreased visuomotor adaptation observed early in training, as well as the moderate correlation between increased mental fatigue and decreased explicit adaptation, suggest that mental fatigue decreases one's ability to engage in explicit processing, limiting the overall extent of initial visuomotor adaptation achieved.
Subject(s)
Adaptation, Physiological , Mental Fatigue , Psychomotor Performance , Humans , Mental Fatigue/physiopathology , Male , Female , Adaptation, Physiological/physiology , Psychomotor Performance/physiology , Adult , Young AdultABSTRACT
We examined age-related changes in intermanual transfer and retention of implicit visuomotor adaptation. We further asked if providing augmented somatosensory feedback regarding movement endpoint would enhance visuomotor adaptation. Twenty young adults and twenty older adults were recruited and randomly divided into an Augmented Feedback group and a Control group. All participants reached to five visual targets with visual feedback rotated 30° counter-clockwise relative to their actual hand motion. Augmented somatosensory feedback was provided at the end of the reach via the robotic handle that participants held. Implicit adaptation was assessed in the absence of visual feedback in the right trained hand and in the left untrained hand following rotated training trials to establish implicit adaptation and intermanual transfer of adaptation respectively. Participants then returned 24 hours later to assess retention in the trained and untrained hands. Results revealed that older adults demonstrated a comparable magnitude of implicit adaptation, transfer and retention of visuomotor adaptation as observed in younger adults, regardless of the presence of augmented somatosensory feedback. To conclude, when visuomotor adaptation is driven implicitly, intermanual transfer and retention do not differ significantly between young and older adults, even when the availability of augmented somatosensory feedback is manipulated.
Subject(s)
Adaptation, Physiological , Psychomotor Performance , Young Adult , Humans , Aged , Feedback, Sensory , Movement , Hand , Visual PerceptionABSTRACT
Background: Proprioceptive acuity and impairments in proprioceptively guided reaches have not been comprehensively examined in people with multiple sclerosis (MS). Objective: To examine proprioceptive acuity in people with MS who self-report and who do not self-report upper limb (UL) impairment, and to determine how people with MS reach proprioceptive targets. Methods: Twenty-four participants with MS were recruited into two groups based on self-reported UL impairment: MS-R (i.e. report UL impairment; n = 12) vs. MS-NR (i.e. do not report UL impairment; n = 12). Proprioception was assessed using ipsilateral and contralateral robotic proprioceptive matching tasks. Results: Participants in the MS-R group demonstrated worse proprioceptive acuity compared to the MS-NR group on the ipsilateral and contralateral robotic matching tasks. Analyses of reaches to proprioceptive targets further revealed that participants in the MS-R group exhibited deficits in movement planning, as demonstrated by greater errors at peak velocity in the contralateral matching task in comparison to the MS-NR group. Conclusion: Our findings suggest that people with MS who self-report UL impairment demonstrate worse proprioceptive acuity, as well as poorer movement planning in comparison to people with MS who do not report UL impairment.
ABSTRACT
Visuomotor adaptation arises when reaching in an altered visual environment, where one's seen hand position does not match their felt (i.e., proprioceptive) hand position in space. Here, we asked if proprioceptive training benefits visuomotor adaptation, and if these benefits arise due to implicit (unconscious) or explicit (conscious strategy) processes. Seventy-two participants were divided equally into 3 groups: proprioceptive training with feedback (PTWF), proprioceptive training no feedback (PTNF), and Control (CTRL). The PTWF and PTNF groups completed passive proprioceptive training, where a participant's hand was moved to an unknown reference location and they judged the felt position of their unseen hand relative to their body midline on every trial. The PTWF group received verbal feedback with respect to their response accuracy on the middle 60% of trials, whereas the PTNF did not receive any feedback during training. The CTRL group did not complete proprioceptive training and instead sat quietly during this time. Following proprioceptive training or time delay, all three groups reached when seeing a cursor that was rotated 30° clockwise relative to their hand motion. The experiment ended with participants completing a series of no-cursor reaches to assess implicit and explicit adaptation. Results indicated that the PTWF group improved the accuracy of their sense of felt hand position following proprioceptive training. However, this improved proprioceptive acuity (i.e., the accuracy of their sense of felt hand) did not benefit visuomotor adaptation, as all three groups showed similar visuomotor adaptation across rotated reach training trials. Visuomotor adaptation arose implicitly, with minimal explicit contribution for all three groups. Together, these results suggest that passive proprioceptive training does not benefit, nor hinder, the extent of implicit visuomotor adaptation established immediately following reach training with a 30° cursor rotation.
Subject(s)
Psychomotor Performance , Visual Perception , Adaptation, Physiological/physiology , Feedback, Sensory/physiology , Hand , Humans , Proprioception/physiology , Psychomotor Performance/physiology , Visual Perception/physiologyABSTRACT
The simultaneous performance of two motor tasks is challenging. Currently, it is unclear how response preparation of a secondary task is impacted by the performance of a continuous primary task. The purpose of the present experiment was to investigate whether the position of the limb performing the primary cyclical tracking task impacts response preparation of a secondary reaction time task. Participants (n = 20) performed a continuous tracking task with their left hand that involved cyclical and targeted wrist flexion and extension. Occasionally, a probe reaction time task requiring isometric wrist extension was performed with the right hand in response to an auditory stimulus (80 or 120 dB) that was triggered when the left hand passed through one of 10 locations identified within the movement cycle. On separate trials, transcranial magnetic stimulation was applied over the left primary motor cortex and triggered at the same 10 stimulus locations to assess corticospinal excitability associated with the probe reaction time task. Results revealed that probe reaction times were significantly longer and motor-evoked potential amplitudes were significantly larger when the left hand was in the middle of a movement cycle compared with an endpoint, suggesting that response preparation of a secondary probe reaction time task was modulated by the phase of movement within the continuous primary task. These results indicate that primary motor task requirements can impact preparation of a secondary task, reinforcing the importance of considering primary task characteristics in dual-task experimental design.
Subject(s)
Motor Cortex , Movement , Electromyography/methods , Evoked Potentials, Motor/physiology , Humans , Motor Cortex/physiology , Movement/physiology , Reaction Time/physiology , Transcranial Magnetic StimulationABSTRACT
Temporal recalibration (TR) may arise to realign asynchronous stimuli after exposure to a short, constant delay between voluntary movement and sensory stimulus. The objective of this study was to determine if awareness of the temporal lag between a motor response (i.e., a keypress) and a sensory event (i.e., a visual flash) is necessary for TR to occur. We further investigated whether manipulating the required motor and perceptual judgment tasks modified the influence of awareness on TR. Participants (n = 48) were randomly divided between two groups (Group 1: Aware and Group 2: Unaware). The Aware group was told of the temporal lag between their keypress and visual flash at the beginning of the experiment, whereas the Unaware group was not. All participants completed eight blocks of trials, in which the motor task (single or repetitive tap), perceptual judgment task (judging the temporal order of the keypress in relation to the visual flash or judging whether the two stimuli were simultaneous or not), and fixed temporal lag between keypress and visual flash (0 or 100 ms) varied. TR was determined by comparing judgments between corresponding blocks of trials in which the temporal lag was 0 or 100 ms. Results revealed that both the Aware and Unaware groups demonstrated a similar magnitude of TR across all motor and perceptual judgment tasks, such that the magnitude of TR did not vary between Aware and Unaware participants. These results suggest that awareness of a temporal lag does not influence the magnitude of TR achieved and that motor and perceptual judgment task demands do not modulate the influence of awareness on TR.
ABSTRACT
It is well documented that reaches are adapted when reaching with a visuomotor distortion (i.e., rotated cursor feedback). Less clear is the influence of awareness on visuomotor adaptation, where awareness encompasses knowledge of the changes in one's reaches and the visuomotor distortion itself. In the current experiment, we asked if awareness governs the magnitude of implicit (i.e., unconscious) visuomotor adaptation achieved, independent of how the distortion is introduced (i.e., abruptly vs. gradually introduced visuomotor distortion), and hence initial errors experienced. Participants were divided into two groups that differed with respect to how the visuomotor distortion was introduced (i.e., Abrupt vs. Gradual Groups) and reached in a virtual environment where a cursor on the screen misrepresented the position of their hand. Participants completed three blocks of 150 reach training trials in the following order: aligned cursor feedback (baseline), rotated cursor feedback (adaptation) and aligned cursor feedback (washout). For the Abrupt Group, the cursor was immediately rotated 45° clockwise (CW) relative to hand motion in the adaptation block, whereas in the Gradual Group, the 45° cursor rotation was gradually introduced over adaptation trials. Following reach training, participants' awareness of changes in their reaches and the visuomotor distortion were established based on a drawing task, where participants drew the path their hand took to get the cursor on target, as well as a post-experiment questionnaire. Participants were subsequently divided into the following 3 groups: Abrupt-Aware (n = 16), Gradual-Aware (n = 11) and Gradual-Unaware (n = 14). Results revealed that errors differed for the Gradual-Unaware Group at the end of adaptation training compared to the Gradual-Aware Group and at the start of the washout block compared to the Abrupt-Aware Group. Errors in the two aware groups did not differ from each other. These results suggest that awareness may lead to reduced implicit adaptation, regardless of the size of initial errors experienced.
Subject(s)
Feedback, Sensory , Proprioception , Adaptation, Physiological , Humans , Movement , Psychomotor Performance , Rotation , Visual PerceptionABSTRACT
The ability to accurately complete goal-directed actions, such as reaching for a glass of water, requires coordination between sensory, cognitive and motor systems. When these systems are impaired, like in people with multiple sclerosis (PwMS), deficits in movement arise. To date, the characterization of upper limb performance in PwMS has typically been limited to results attained from self-reported questionnaires or clinical tools. Our aim was to characterize visually guided reaching performance in PwMS. Thirty-six participants (12 PwMS who reported upper limb impairment (MS-R), 12 PwMS who reported not experiencing upper limb impairment (MS-NR), and 12 age- and sex-matched control participants without MS (CTL)) reached to 8 targets in a virtual environment while seeing a visual representation of their hand in the form of a cursor on the screen. Reaches were completed with both the dominant and non-dominant hands. All participants were able to complete the visually guided reaching task, such that their hand landed on the target. However, PwMS showed noticeably more atypical reaching profiles when compared to control participants. In accordance with these observations, analyses of reaching performance revealed that the MS-R group was more variable with respect to the time it took to initiate and complete their movements compared to the CTL group. While performance of the MS-NR group did not differ significantly from either the CTL or MS-R groups, individuals in the MS-NR group were less consistent in their performance compared to the CTL group. Together these findings suggest that PwMS with and without self-reported upper limb impairment have deficits in the planning and/or control of their movements. We further argue that deficits observed during movement in PwMS who report upper limb impairment may arise due to participants compensating for impaired movement planning processes.
Subject(s)
Multiple Sclerosis/physiopathology , Psychomotor Performance/classification , Upper Extremity/physiology , Adult , Canada , Female , Hand/physiology , Hand Strength/physiology , Humans , Male , Middle Aged , Movement/physiology , Physical Therapy Modalities , Psychomotor Performance/physiology , Self Report , Sensorimotor Cortex/physiologyABSTRACT
Goal-directed reaches are modified based on previous errors experienced (i.e., offline control) and current errors experienced during movement execution (i.e., online control). It is well documented that the control processes (i.e., offline and online control) underlying well learned movements change based on the time available to complete an action, such that offline control processes are engaged to a greater extent when movements are completed in a faster movement time (MT). Here, we asked if the underlying movement control processes governing newly acquired movements also change under varying MT constraints. Sixteen participants adapted their movements to a visuomotor distortion. Following reach training trials, participants reached under Long (800-1000 ms) and Short (400-500 ms) MT constraints. Results indicate that movement errors when reaching with the rotated cursor were reduced online under the Long MT constraint compared to the Short MT constraint. Thus, the contributions of offline and online movement control processes engaged in newly acquired movements can be adjusted with changes in temporal demands.
Subject(s)
Adaptation, Physiological , Psychomotor Performance , Humans , Learning , Movement , Visual PerceptionABSTRACT
When reaching to targets within arm's reach, intentional trunk motion must be neutralized by compensatory motion of the upper limb (UL). Advanced age has been associated with deterioration in the coordination of multi-joint UL movements. In the current study, we looked to determine if older adults also have difficulties modifying their UL movements (i.e., coordination between the shoulder and elbow joints), during a complex reaching task when trunk motion is manipulated. Two groups of healthy participants were recruited: 18 young (mean age = 24.28 ± 2.89 years old) and 18 older (mean age = 72.11 ± 2.39 years old) adults. Participants reached to a target with their eyes closed, while simultaneously moving the trunk forward. In 40% of trials, the trunk motion was unexpectedly blocked. Participants performed the task with both their dominant and non-dominant arms, and at a preferred and fast speed. All participants were able to coordinate motion at the elbow and shoulder joints in a similar manner and modify this coordination in accordance with motion at the trunk, regardless of the hand used or speed of movement. Specifically, in reaches that involved forward trunk motion (free-trunk trials), all participants demonstrated increased elbow flexion (i.e., less elbow extension) compared to blocked-trunk trials. In contrast, when trunk motion was blocked (blocked-trunk trials), all reaching movements were accompanied by increased shoulder horizontal adduction. While coordination of UL joints was similar across older and young adults, the extent of changes at the elbow and shoulder was smaller and less consistent in older adults compared to young participants, especially when trunk motion was involved. These results suggest that older adults can coordinate their UL movements based on task requirements, but that their performance is not as consistent as young adults.
Subject(s)
Arm , Psychomotor Performance , Aged , Biomechanical Phenomena , Hand , Humans , Infant, Newborn , Movement , Torso , Young AdultABSTRACT
Individuals with Parkinson's disease (PD) and healthy adults demonstrate similar levels of visuomotor adaptation provided that the distortion is small or introduced gradually, and hence, implicit processes are engaged. Recently, implicit processes underlying visuomotor adaptation in healthy individuals have been proposed to include proprioceptive recalibration (i.e., shifts in one's proprioceptive sense of felt hand position to match the visual estimate of their hand experienced during reaches with altered visual feedback of the hand). In the current study, we asked if proprioceptive recalibration is preserved in PD patients. PD patients tested during their "off" and "on" medication states and age-matched healthy controls reached to visual targets, while visual feedback of their unseen hand was gradually rotated 30° clockwise or translated 4 cm rightwards of their actual hand trajectory. As expected, PD patients and controls produced significant reach aftereffects, indicating visuomotor adaptation after reaching with the gradually introduced visuomotor distortions. More importantly, following visuomotor adaptation, both patients and controls showed recalibration in hand position estimates, and the magnitude of this recalibration was comparable between PD patients and controls. No differences for any measures assessed were observed across medication status (i.e., PD off vs PD on). Results reveal that patients are able to adjust their sensorimotor mappings and recalibrate proprioception following adaptation to a gradually introduced visuomotor distortion, and that dopaminergic intervention does not affect this proprioceptive recalibration. These results suggest that proprioceptive recalibration does not involve striatal dopaminergic pathways and may contribute to the preserved visuomotor adaptation that arises implicitly in PD patients.
Subject(s)
Parkinson Disease , Adaptation, Physiological , Adult , Humans , Proprioception , Psychomotor Performance , Visual PerceptionABSTRACT
Reaching with a visuomotor distortion in a virtual environment leads to reach adaptation in the trained hand, and in the untrained hand. In the current study we asked if reach adaptation in the untrained (right) hand is due to transfer of explicit adaptation (EA; strategic changes in reaches) and/or implicit adaptation (IA; unconscious changes in reaches) from the trained (left) hand, and if this transfer changes depending on instructions provided. We further asked if EA and IA are retained in both the trained and untrained hands. Participants (n = 60) were divided into 3 groups (Instructed (provided with instructions on how to counteract the visuomotor distortion), Non-Instructed (no instructions provided), and Control (EA not assessed)). EA and IA were assessed in both the trained and untrained hands immediately following rotated reach training with a 40° visuomotor distortion, and again 24 hours later by having participants reach in the absence of cursor feedback. Participants were to reach (1) so that the cursor landed on the target (EA + IA), and (2) so that their hand landed on the target (IA). Results revealed that, while initial EA observed in the trained hand was greater for the Instructed versus Non-Instructed group, the full extent of EA transferred between hands for both groups and was retained across days. IA observed in the trained hand was greatest in the Non-Instructed group. However, IA did not significantly transfer between hands for any of the three groups. Limited retention of IA was observed in the trained hand. Together, these results suggest that while initial EA and IA in the trained hand are dependent on instructions provided, transfer and retention of visuomotor adaptation to a large visuomotor distortion are driven almost exclusively by EA.
Subject(s)
Adaptation, Physiological , Feedback, Sensory/physiology , Proprioception/physiology , Psychomotor Performance/physiology , Visual Perception/physiology , Adult , Female , Humans , MaleABSTRACT
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.
Subject(s)
Movement/physiology , Proprioception/physiology , Visual Perception/physiology , Adaptation, Physiological/physiology , Feedback, Sensory/physiology , Female , Hand/physiology , Humans , Male , Virtual Reality , Young AdultABSTRACT
Muscle fatigue is a complex phenomenon, consisting of central and peripheral mechanisms which contribute to local and systemic changes in motor performance. In particular, it has been demonstrated that afferent processing in the fatigued muscle (e.g., shoulder), as well as in surrounding or distal muscles (e.g., hand) can be altered by fatigue. Currently, it is unclear how proximal muscle fatigue affects proprioceptive acuity of the distal limb. The purpose of the present study was to assess the effects of shoulder muscle fatigue on participants' ability to judge the location of their hand using only proprioceptive cues. Participants' (Nâ¯=â¯16) limbs were moved outwards by a robot manipulandum and they were instructed to estimate the position of their hand relative to one of four visual reference targets (two near, two far). This estimation task was completed before and after a repetitive pointing task was performed to fatigue the shoulder muscles. To assess central versus peripheral effects of fatigue on the distal limb, the right shoulder was fatigued and proprioceptive acuity of the left and right hands were tested. Results showed that there was a significant decrease in the accuracy of proprioceptive estimates for both hands after the right shoulder was fatigued, with no change in the precision of proprioceptive estimates. A control experiment (Nâ¯=â¯8), in which participants completed the proprioceptive estimation task before and after a period of quiet sitting, ruled out the possibility that the bilateral changes in proprioceptive accuracy were due to a practice effect. Together, these results indicate that shoulder muscle fatigue decreases proprioceptive acuity in both hands, suggesting that central fatigue mechanisms are primarily responsible for changes in afferent feedback processing of the distal upper limb.
ABSTRACT
Human movements are remarkably adaptive. We are capable of completing movements in a novel visuomotor environment with similar accuracy to those performed in a typical environment. In the current study, we examined if the control processes underlying movements under typical conditions were different from those underlying novel visuomotor conditions. 16 participants were divided into two groups, one receiving continuous visual feedback during all reaches (CF), and the other receiving terminal feedback regarding movement endpoint (TF). Participants trained in a virtual environment by completing 150 reaches to three targets when (1) a cursor accurately represented their hand motion (i.e., typical environment) and (2) a cursor was rotated 45° clockwise relative to their hand motion (i.e., novel environment). Analyses of within-trial measures across 150 reaching trials revealed that participants were able to demonstrate similar movement outcomes (i.e., movement time and angular errors) regardless of visual feedback or reaching environment by the end of reach training. Furthermore, a reduction in variability across several measures (i.e., reaction time, movement time, time after peak velocity, and jerk score) over time showed that participants improved the consistency of their movements in both reaching environments. However, participants took more time and were less consistent in the timing of initiating their movements when reaching in a novel environment compared to reaching in a typical environment, even at the end of training. As well, angular error variability at different proportions of the movement trajectory was consistently greater when reaching in a novel environment across trials and within a trial. Together, the results suggest a greater contribution of offline control processes and less effective online corrective processes when reaching in a novel environment compared to when reaching in a typical environment.
Subject(s)
Adaptation, Physiological/physiology , Feedback, Sensory/physiology , Motor Activity/physiology , Psychomotor Performance/physiology , Adult , Biomechanical Phenomena , Female , Humans , Male , User-Computer Interface , Young AdultABSTRACT
Recent research has suggested that visual discrimination and detection may be enhanced during movement preparation and execution, respectively. The current study examined if visual perceptual processing is augmented prior to or during a movement through the use of an Inspection Time (IT) task. The IT task involved briefly presenting (e.g., 15-105 ms) a "pi" figure with differing leg lengths, which was then immediately masked for 400 ms to prevent retinal afterimages. Participants were subsequently required to choose which of the two legs was longer. In Experiment 1, participants (n = 28) completed the IT task under three movement conditions: no-movement (NM), foreperiod (FP), and peak velocity (PV). In the NM condition, participants solely engaged in the IT paradigm. In the FP condition, the IT stimulus was presented prior to movement execution when response planning was expected to occur. Finally, in the PV condition, participants made a rapid movement to a target, and the IT stimulus was presented when their limb reached peak velocity. In Experiment 2, participants (n = 18) also performed the IT task in the PV and NM condition; however, vision of the limb's motion was made available during the PV trials (PV-FV) to investigate the potential influence of visual feedback on IT performance. Results showed no significant differences in performance in the IT task between the NM and FP conditions, suggesting no enhancement of visual processing occurred due to response preparation (Experiment 1). However, IT performance was significantly poorer in the PV condition in comparison to both the NM and FP conditions (Experiment 1), and was even worse when visual feedback was provided (Experiment 2). Together, these findings suggest that visual perceptual processing is degraded during execution of a fast, goal-directed movement.
Subject(s)
Feedback, Sensory/physiology , Movement , Psychomotor Performance/physiology , Reaction Time/physiology , Visual Perception/physiology , Adult , Female , Humans , MaleABSTRACT
Reaching for an object is a basic motor skill that requires precise coordination between elbow, shoulder and trunk motion. The purpose of this research study was to examine age-related differences in compensatory arm-trunk coordination during trunk-assisted reaching. To engage the arm and trunk, an older and younger group of participants were asked to (1) maintain a fixed hand position while flexing forward at the trunk [stationary hand task (SHT)] and (2) reach to a within-arm's reach target while simultaneously flexing forward at the trunk [reaching hand task (RHT)] (Raptis et al. in J Neurophysiol 97:4069-4078, 2007; Sibindi et al. in J Vestib Res 23:237-247, 2013). Both tasks were completed with eyes closed. Participants completed the two tasks with their dominant and non-dominant arms, and at both a fast and a preferred speed. On average, young and older participants performed in a similar manner in the SHT, such that they maintained their hand position by compensating for trunk movement with modifications of the elbow and shoulder joints. In the RHT, young and older participants had similar endpoint accuracy. This similarity in performance between young and older participants in the SHT and RHT tasks was observed regardless of the arm used or movement speed. However, for both tasks, movements in older adults were significantly more variable compared to younger adults as shown by the larger variability in arm-trunk coordination performance (gain scores) in the SHT and higher movement time variability in the RHT. Thus, results imply that older adults maintain their ability to coordinate arm and trunk movements efficiently during reaching actions but are not as consistent as younger adults.
Subject(s)
Aging/physiology , Arm/physiology , Movement/physiology , Psychomotor Performance/physiology , Range of Motion, Articular/physiology , Torso/physiology , Adult , Aged , Analysis of Variance , Arm/innervation , Female , Functional Laterality , Humans , Male , Torso/innervation , Young AdultABSTRACT
The ability to mentally represent actions is suggested to play a role in the online control of movement in healthy adults. Children's movement imagery ability and online control have been shown to develop at similar nonlinear rates. The current study investigated the relationship between movement imagery and online control in children by comparing implicit and explicit movement imagery measures with the ability to make online trajectory corrections. Imagery ability was a significant predictor of children's online control of movement once general reaching efficiency was controlled for. These findings extend the proposed relationship between movement imagery and online control.
Subject(s)
Child Development/physiology , Imagination/physiology , Movement , Psychomotor Performance , Child , Female , Humans , MaleABSTRACT
Explicit (strategic) and implicit (unconscious) processes play a role in visuomotor adaptation (Bond and Taylor, J Neurophysiol 113:3836-3849, https://doi.org/10.1152/jn.00009.2015 , 2015; Werner et al., PLoS ONE 10:1-18, https://doi.org/10.1371/journal.pone.0123321 , 2015). We investigated the contributions of explicit and implicit processes to visuomotor adaptation when awareness was manipulated directly vs. indirectly, and asked how these contributions changed over time. Participants were assigned to a Strategy or No-Strategy group. Those in the Strategy group were made aware of the visuomotor distortion directly. Participants were further subdivided into groups to train with a large (60°), medium (40°) or small (20°) visuomotor distortion, providing the potential for awareness to develop indirectly. Participants reached with their respective distorted cursor, followed by a series of no-cursor reaches to assess the contributions of explicit and implicit processes to visuomotor adaptation after every 30 reach training trials. Within the no-cursor reaching trials, participants reached (1) with any strategies they had gained during training (explicit + implicit processes), and (2) as accurately to the target as possible (implicit processes). Results showed that implicit contributions were greatest in the No-Strategy group, took time to develop, and were transient, as partial decay was seen following a 5-min rest. As well, implicit contributions were similar (i.e., plateaued), regardless of the rotation size participants trained with. In contrast, explicit contributions were greatest in the Strategy group, increased with rotation size, and remained consistent over time. Taken together, results reveal that there are notable differences in the stability of explicit and implicit processes and their potential to contribute to visuomotor adaptation depending on if awareness is provided directly.
Subject(s)
Adaptation, Physiological/physiology , Adaptation, Psychological , Awareness/physiology , Psychomotor Performance/physiology , Rotation , Adolescent , Adult , Analysis of Variance , Feedback, Sensory , Female , Humans , Male , Surveys and Questionnaires , Teaching , Time Factors , Visual Perception , Young AdultABSTRACT
Sensorimotor changes are well documented following reaches with altered visual feedback of the hand. Specifically, reaches are adapted and proprioceptive estimates of felt hand position shifted in the direction of the visual feedback experienced. While research has examined one's ability to retain reach adaptation, limited attention has been given to the retention of proprioceptive recalibration. This experiment examined retention of proprioceptive recalibration in the form of recall and savings (i.e., faster proprioceptive recalibration on subsequent testing days) over an extended period of time (i.e., four days). As well, we looked to determine the benefits of additional training on short-term retention (i.e., one day) of proprioceptive recalibration. Twenty-four participants trained to reach to a visual target while seeing a cursor that was rotated 30° clockwise relative to their hand on an initial day of testing. Half of the participants then completed additional reach training trials on 4 subsequent testing days (Training group), whereas the second half of participants did not complete additional training until Day 5 (Non-Training group). Participants provided estimates of their felt hand position on all 5 testing days to establish retention of proprioceptive recalibration. Results revealed that proprioceptive recalibration was recalled 24â¯h after initial training across all participants. Recall of proprioceptive recalibration was not observed on subsequent testing days for the Non-Training group, while recall of proprioceptive recalibration was retained at a similar level across all subsequent testing days for the Training group. Retention of proprioceptive recalibration in the form of savings was observed on Day 5 in the Non-Training group. These results reveal that short-term recall of proprioceptive recalibration does not benefit from additional training. Moreover, the different time scales (i.e., retention in the form of recall seen only at 24â¯h after initial training versus savings observed 4 days after initial training in the Non-Training group), suggest that distinct processes may underlie recall and savings of proprioceptive recalibration.