Perceptuomotor Task Research Articles

Locomotor circumvention strategies are altered by stroke: I. Obstacle clearance

BackgroundFunctional locomotion requires the ability to adapt to environmental challenges such as the presence of stationary or moving obstacles. Difficulties in obstacle circumvention often lead to restricted community ambulation in individuals with stroke. The objective of this study was to contrast obstacle circumvention strategies between post-stroke (n = 12) and healthy individuals (n = 12) performing locomotor and perceptuomotor (joystick navigation) tasks with different obstacle approaches.MethodsParticipants walked and navigated with a joystick towards a central target, in a virtual environment simulating a large room, while avoiding an obstacle that either remained stationary at the pre-determined point of intersection or moved from head-on or diagonally 30° left/right. The outcome measures included dynamic clearance (DC), instantaneous distance from obstacle at crossing (IDC), number of collisions and preferred side of circumvention. These measures were compared between groups (stroke vs. healthy), obstacle parameter (stationary vs. moving head-on) and direction of approach (left/paretic vs. right/non-paretic).ResultsDC was significantly larger when circumventing a moving obstacle that approached head-on as compared to a stationary obstacle for both groups during both tasks, while not significantly different in either diagonal approach in either group. IDC was smaller in the stroke group while walking and larger in both groups during joystick navigation when avoiding moving as compared to stationary obstacle. IDC was significantly larger in the stroke group compared to controls for diagonal approaches during walking, wherein two different strategies emerged amongst individuals with stroke: circumventing to the same (Vsame n = 6) or opposite (Vopp n = 4) side of obstacle approach. This behavior was not seen in the perceptuomotor task, wherein post-stroke participants circumvented to opposite side of the obstacle approach as seen in healthy participants. In the locomotor task, the Vsame subgroup that had greater functional limitations used larger DC as compared to the Vopp subgroup and healthy individuals. The remaining two individuals with stroke collided with obstacles in >50% trials of either obstacle approach. The underlying mechanisms for collision were however different for both individuals.ConclusionAvoidance strategies in individuals with stroke can vary depending on the individual locomotor capabilities and obstacle characteristics.

Interaction of Perception and Action in Discrete and Continuous Rapid Aiming Tasks

ABSTRACTPreviously, we have shown that discrete and continuous rapid aiming tasks are governed by distinct visuomotor control mechanisms by assessing the combined visual illusion effects on the perceived and effective index of difficulty (ID). All participants were perceptually biased by the combined visual illusion before they performed the rapid aiming tasks. In the current study, the authors manipulated the order of performing perceptual and motor tasks to examine whether perceptual or motor experience with the illusory visual target would influence the subsequent perceived and effective ID in discrete and continuous tapping tasks. The results supported our hypothesis showing that perceptual experience with the illusory visual target in the discrete condition reduced the effective ID in the subsequent discrete tapping task, and motor experience with the illusory visual target in the continuous condition reduced the illusion effects on the perceived ID in the subsequent perceptual judgment task. The study demonstrates the coinfluence of perception and action, and suggests that perception and action influence one another with different magnitude depending on the spatial frame of reference used to perform the perceptuomotor task.

Can Perceptuo-Motor Skills Assessment Outcomes in Young Table Tennis Players (7-11 years) Predict Future Competition Participation and Performance? An Observational Prospective Study.

Forecasting future performance in youth table tennis players based on current performance is complex due to, among other things, differences between youth players in growth, development, maturity, context and table tennis experience. Talent development programmes might benefit from an assessment of underlying perceptuo-motor skills for table tennis, which is hypothesized to determine the players’ potential concerning the perceptuo-motor domain. The Dutch perceptuo-motor skills assessment intends to measure the perceptuo-motor potential for table tennis in youth players by assessing the underlying skills crucial for developing technical and tactical qualities. Untrained perceptuo-motor tasks are used as these are suggested to represent a player’s future potential better than specific sport skills themselves as the latter depend on exposure to the sport itself. This study evaluated the value of the perceptuo-motor skills assessment for a talent developmental programme by evaluating its predictive validity for competition participation and performance in 48 young table tennis players (7–11 years). Players were tested on their perceptuo-motor skills once during a regional talent day, and the subsequent competition results were recorded half-yearly over a period of 2.5 years. Logistic regression analysis showed that test scores did not predict future competition participation (p >0.05). Yet, the Generalized Estimating Equations analysis, including the test items ‘aiming at target’, ‘throwing a ball’, and ‘eye-hand coordination’ in the best fitting model, revealed that the outcomes of the perceptuo-motor skills assessment were significant predictors for future competition results (R2 = 51%). Since the test age influences the perceptuo-motor skills assessment’s outcome, another multivariable model was proposed including test age as a covariate (R2 = 53%). This evaluation demonstrates promising prospects for the perceptuo-motor skills assessment to be included in a talent development programme. Future studies are needed to clarify the predictive value in a larger sample of youth competition players over a longer period in time.

Dynamic clearance measure to evaluate locomotor and perceptuo-motor strategies used for obstacle circumvention in a virtual environment

Circumvention around an obstacle entails a dynamic interaction with the obstacle to maintain a safe clearance. We used a novel mathematical interpolation method based on the modified Shepard’s method of Inverse Distance Weighting to compute dynamic clearance that reflected this interaction as well as minimal clearance. This proof-of-principle study included seven young healthy, four post-stroke and four healthy age-matched individuals. A virtual environment designed to assess obstacle circumvention was used to administer a locomotor (walking) and a perceptuo-motor (navigation with a joystick) task. In both tasks, participants were asked to navigate towards a target while avoiding collision with a moving obstacle that approached from either head-on, or 30° left or right. Among young individuals, dynamic clearance did not differ significantly between obstacle approach directions in both tasks. Post-stroke individuals maintained larger and smaller dynamic clearance during the locomotor and the perceptuo-motor task respectively as compared to age-matched controls. Dynamic clearance was larger than minimal distance from the obstacle irrespective of the group, task and obstacle approach direction. Also, in contrast to minimal distance, dynamic clearance can respond differently to different avoidance behaviors. Such a measure can be beneficial in contrasting obstacle avoidance behaviors in different populations with mobility problems.

Attention and postural control in patients with conversion paresis

ObjectiveCurrent theories of conversion disorder (CD) propose that motor symptoms are related to heightened self-monitoring and excessive cognitive control of movements. We tested this hypothesis using quantification of performance on a continuous perceptuo-motor task involving quiet standing. MethodsTwelve CD patients and matched controls maintained static balance on a force platform under various attention conditions: (1) with eyes open; (2) with eyes closed (requiring enhanced attention to proprioceptive information to regulate posture); and (3) while performing an attention demanding cognitive task. ResultsCompared to controls, CD patients displayed a greater decrease in postural stability in the ‘eyes-closed’ versus ‘eyes-open’ condition. In contrast, cognitive distraction led to a normalization of balance in CD. Moreover, sensitivity to the balance interventions correlated significantly with trauma reports and dissociative symptoms. ConclusionThese results indicate that attention plays a crucial role in postural control in CD. More specifically, patients seem to inadvertently use deliberate control of posture (i.e., cognitive investment) of an otherwise nearly automatized perceptuo-motor task. Attentional distraction resulted in a temporary normalization of balance, which may be used to train individuals with CD to guide their attention in a more effective way.

Perceptual and locomotor factors affect obstacle avoidance in persons with visuospatial neglect

BackgroundFor safe ambulation in the community, detection and avoidance of static and moving obstacles is necessary. Such abilities may be compromised by the presence of visuospatial neglect (VSN), especially when the obstacles are present in the neglected, i.e. contralesional field.MethodsTwelve participants with VSN were tested in a virtual environment (VE) for their ability to a) detect moving obstacles (perceptuo-motor task) using a joystick with their non-paretic hand, and b) avoid collision (locomotor task) with moving obstacles while walking in the VE. The responses of the participants to obstacles approaching on the contralesional side and from head-on were compared to those during ipsilesional approaches.ResultsUp to 67 percent of participants (8 out of 12) collided with either contralesional or head-on obstacles or both. Delay in detection (perceptuo-motor task) and execution of avoidance strategies, and smaller distances from obstacles (locomotor task) were observed for colliders compared to non-colliders. Participants’ performance on the locomotor task was not explained by clinical measures of VSN but slower walkers displayed fewer collisions.ConclusionPersons with VSN are at the risk of colliding with dynamic obstacles approaching from the contralesional side and from head-on. Locomotor-specific assessments of navigational abilities are needed to appreciate the recovery achieved or challenges faced by persons with VSN.

Altered steering strategies for goal-directed locomotion in stroke

BackgroundIndividuals who have sustained a stroke can manifest altered locomotor steering behaviors when exposed to optic flows expanding from different locations. Whether these alterations persist in the presence of a visible goal and whether they can be explained by the presence of a perceptuo-motor disorder remain unknown. The purpose of this study was to compare stroke participants and healthy participants on their ability to control heading while exposed to changing optic flows and target locations.MethodsTen participants with stroke (55.6 ± 9.3 yrs) and ten healthy controls (57.0 ± 11.5 yrs) participated in a mouse-driven steering task (perceptuo-motor task) while seated and in a walking steering task. In the seated steering task, participants were instructed to head or ‘walk’ toward a target in the virtual environment by using a mouse while wearing a helmet-mounted display (HMD). In the walking task, participants performed a similar steering task in the same virtual environment while walking overground at their comfortable speed. For both experiments, the target and/or the focus of expansion (FOE) of the optic flow shifted to the side (±20°) or remained centered. The main outcome measure was net heading errors (NHE). Secondary outcomes included mediolateral displacement, horizontal head orientation, and onsets of heading and head reorientation.ResultsIn the walking steering task, the presence of FOE shifts modulated the extent and timing of mediolateral displacement and head rotation changes, as well as NHE magnitudes. Participants overshot and undershot their net heading, respectively, in response to ipsilateral and contralateral FOE and target shifts. Stroke participants made larger NHEs, especially when the FOE was shifted towards the non-paretic side. In the seated steering task, similar NHEs were observed between stroke and healthy participants.ConclusionsThe findings highlight the fine coordination between rotational and translational steering mechanisms in presence of targets and FOE shifts. The altered performance of stroke participants in walking but not in the seated steering task suggests that an altered perceptuo-motor processing of optic flow is not a main contributing factor and that other stroke-related sensorimotor deficits are involved.

Experience-dependent alterations in conscious resting state activity following perceptuomotor learning

In monkeys and rats, neural activity patterns during learning are reactivated during subsequent periods of rest or sleep. According to the reactivation–consolidation account, this process underlies the consolidation of memories. Brain imaging studies have extended these findings to humans during sleep, but not yet, during rest. Here, we show that learning-related reactivation also occurs in humans during rest. During functional MRI-scanning, participants trained on a perceptuomotor task flanked by rest periods. During training, we found robust activity in the superior parietal cortex. During post-training rest, this same area reactivated. We also found a link between parietal reactivation and learning. Activity in superior parietal cortex was associated with learning during training, and a control group that did not train on the perceptuomotor task did not show any difference between the pre- and post-training rest blocks in this region. These findings indicate that, during rest, reactivation also occurs in humans. This process may contribute to consolidation of perceptuomotor memories.

Compensatory manual motor responses while object wielding during combined linear visual and physical roll tilt stimulation

Dynamic signals from multiple sensory channels must be integrated by the central nervous system to create a unified perception of self-motion and spatial orientation. Using immersive virtual environments, we altered the relative contribution of visual and inertial inputs and evaluated the effects on perceptuomotor outputs. Subjects seated in a tilting chair were exposed to a combined 0.25 Hz sinusoidal roll-tilt (+/-7.5 degrees) about the naso-occipital axis while viewing one of four visual conditions. One visual condition was in darkness, and the other three depicted 2 m of sinusoidal horizontal or vertical linear motion either synchronous or asynchronous with the roll-tilt. Subjects performed a perceptuomotor task of aligning a handheld object to gravitational vertical (GV) with the entire arm being free to move in six degrees of freedom. Subjects were tested with two objects, a joystick and glass of water, in counter-balanced order. Specific visual effects were as follows: (1) the phase leads of object tilt relative to chair/subject roll-tilt were affected by visual condition, (2) horizontal translation of the object was entrained with visual velocity, rather than with visual acceleration or maximum roll-tilt, and (3) when vertical visual motion was viewed during chair/subject roll-tilt, vertical object translation increased. Although the head-fixed scene meant visual vertical cues were always aligned with the subject's median sagittal plane, object tilt showed sensitivity to inertial roll-tilt (Gain > 0.5) which was not significantly different from the dark condition. Two object effects were found: (1) tilt deviation from GV was greater when wielding a joystick compared to a full glass of water, and (2) the phase of horizontal visual motion relative to subject roll tilt affected the joystick amplitude of horizontal translation but not the glass of water. In conclusion, an attentional shift driven by postural assumptions can account for the two object effects, however, the visual effects suggest that a process for deriving the net gravitoinertial force from visual and inertial cues is involved. Inertial signals dominated the perception of verticality, but visual linear translation affected the spatiotemporal dynamics of the manual motor responses during object wielding.

Parkinson's disease shows perceptuomotor asymmetry unrelated to motor symptoms

Evidence of neglect symptoms in Parkinson's disease (PD) have been reported during visuoperceptual tasks and linked to side of disease onset. The goal of this study was to determine if in PD perceptual asymmetry is also evident in perceptuomotor tasks without visual input. The task was to point to a remembered straight-ahead (SA) target in peripersonal space. During baseline pointing, a bias left of SA was evident in PD patients and right of SA in healthy controls. To evaluate whether this was linked to a proprioceptive bias in PD, pointing during axial twisting of the trunk was tested. Axial rotation (±15°, 1° s −1) of the lower-body about shoulders fixed against rotation induced a non-veridical perception of upper-body rotation and lower-body stationarity. Pointing endpoints were shifted right of the actual SA during clockwise (CW) lower-body rotation and left of SA during counter-clockwise (CC) rotation, despite the fact that the shoulders and head were not rotated. In PD patients, endpoints relative to SA were shifted less during CW than CC rotation of the lower-body, whereas controls showed symmetrical pointing. Levodopa did not significantly change this bias. Both hands were tested in each subject and bias appeared regardless of hand used. Neither disease progression nor side of disease onset was linked to the direction or size of pointing bias. These findings suggest that PD manifests a contraction of left external hemispace relative to right hemispace, which affects generation and execution of motor commands throughout disease progression.

Memory in Early Adolescents Born Prematurely: A Functional Magnetic Resonance Imaging Investigation

This study employed functional magnetic resonance imaging to examine the functional neuroanatomy of the hippocampus and head of the caudate nucleus during 2 different types of memory tasks in a sample of 9 early adolescent children who were born preterm (neonatal intensive care unit [NICU] sample) and a group of 9 age-matched control children who were born at term. The investigation employed delayed match to sample (DMS), delayed nonmatch to sample (DNMS), and spatial memory span tasks, as well as 2 analogous perceptuomotor tasks that placed no demands on memory. The general question examined was whether preterm children show different levels of hippocampal and caudate activation during these tasks when compared to children born at term. The findings indicated that the 2 groups did not differ in functional activation of the hippocampus during the DMS and DNMS tasks. During the encoding phase of the spatial memory span task, the DMS perceptuomotor task, and the spatial memory span perceptuomotor task, the NICU sample showed greater activation change in the right caudate nucleus, and less right caudate activation change during the test phase. During the spatial span perceptuomotor task, the preterm group showed reduced activation change in the left caudate nucleus during both the encoding and test phase. Also, during the DMS perceptuomotor task, the NICU group showed increased activation change in the left caudate nucleus during encoding and decreased activation change at test. The implications of these findings for understanding the functional neuroanatomy of memory deficits are discussed, as is the potential for distinguishing the effects of neural plasticity from those of typical brain maturational processes.

Specific learning disabilities in children: deficits and neuropsychological profile

The public is gradually becoming aware of specific learning disabilities (SLDs), which are very often the cause of academic difficulties. The aim of the study was to assess the SLDs in the clinic population at the Child and Adolescent Psychiatry Clinic at the Postgraduate Institute of Medical Education and Research (PGIMER), Chandigarh using the National Institute of Mental Health and Neurosciences SLD index and subsequently to assess the children's neuropsychological functions using a battery of tests. Thirty-five children in the age range of 7-14 years (both boys and girls) were recruited as the cohort, diagnosed clinically and assessed using the battery of tests for SLDs and neuropsychological tests consisting of the PGIMER memory scale for children, the Wisconsin card sorting test, the Bender visuo-motor gestalt test and Malin's intelligence scale for Indian children. The study revealed deficits in language and writing skills and impairments in specific areas of memory, executive functions and perceptuo-motor tasks. Identification of SLDs is useful in drawing up a treatment plan specific for a particular child.

Performance of a skilled motor task in virtual and real environments

Three experiments compared the performances of adult participants (three groups of 10) on a perceptuo-motor task in both real world (RW) and virtual environments (VEs). The task involved passing a hoop over a bent wire course, and three versions of the task were used: a 3-D wire course with no background, a flattened version of the 3-D course (2½-D course) with no background, and the 2½-D course with added background to provide spatial context. In all three experiments the participants had to prevent the hoop from touching the wire as they moved it. In the first experiment, the VE condition produced about 18 times more errors than the RW task. The VE 2½-D task was found to be as difficult as the 3-D, and the 2½-D with the added background produced more errors than the other two experiments. Taken together, the experiments demonstrate the difficulty of performing fine motor tasks in VEs, a phenomenon that has not been given due attention in many previous studies of motor control in VEs.

Human hippocampal activation in the delayed matching-and nonmatching-to-sample memory tasks: An event-related functional MRI approach.

The delayed matching-to-sample (DMS) and delayed nonmatching-to-sample (DNMS) memory tasks are standard tools used to probe visual recognition memory in human and nonhuman primates. Previous research indicates that structures within the medial temporal lobe, including the hippocampus, make up a crucial memory circuit for successful performance on these tasks. In the present investigation, event-related functional magnetic resonance imaging was used to examine activation in the hippocampus proper during these memory tasks relative to a perceptuomotor task involving the same stimuli. The results indicate that both memory tasks elicited greater activation in the right hippocampus during the encoding phase. These findings are consistent with the work from human patients and animal studies, indicating hippocampal involvement in the DMS and DNMS tasks.

Human hippocampal activation in the delayed matching- and nonmatching-to-sample memory tasks: an event-related functional MRI approach.

The delayed matching-to-sample (DMS) and delayed nonmatching-to-sample (DNMS) memory tasks are standard tools used to probe visual recognition memory in human and nonhuman primates. Previous research indicates that structures within the medial temporal lobe, including the hippocampus, make up a crucial memory circuit for successful performance on these tasks. In the present investigation, event-related functional magnetic resonance imaging was used to examine activation in the hippocampus proper during these memory tasks relative to a perceptuomotor task involving the same stimuli. The results indicate that both memory tasks elicited greater activation in the right hippocampus during the encoding phase. These findings are consistent with the work from human patients and animal studies, indicating hippocampal involvement in the DMS and DNMS tasks.

A neural basis for general intelligence

The Spearman hypothesis is that a general factor of intelligence (g) represents what is general or common to all the abilities that constitute the intelligence quotient (IQ). The Thomson hypothesis is that g as a collection of multitudinous and diverse skills needed to complete most intellectual tasks. The authors of this article used positron emission tomography (PET) to monitor brain activation in volunteers performing different spatial, verbal and perceptuo-motor tasks. They then asked which hypothesis, Spearman’s or Thomson’s, was best supported by their PET scan data. The authors report that the performance of tasks that are good measures of g results in activation of portions of the brain’s frontal lobes. They interpret their results as supporting thg Spearman hypothesis, since the frontal area of the brain, rather than many areas, is primarily activated during performance of different g-based tasks. The authors propose that the neural circuitry of the frontal lobes is the basis of intelligence, although no more than a correlational relationship was shown. The functional significance of these findings is unknown.—Hans E. Grossniklaus

A neural basis for general intelligence.

Universal positive correlations between different cognitive tests motivate the concept of "general intelligence" or Spearman's g. Here the neural basis for g is investigated by means of positron emission tomography. Spatial, verbal, and perceptuo-motor tasks with high-g involvement are compared with matched low-g control tasks. In contrast to the common view that g reflects a broad sample of major cognitive functions, high-g tasks do not show diffuse recruitment of multiple brain regions. Instead they are associated with selective recruitment of lateral frontal cortex in one or both hemispheres. Despite very different task content in the three high-g-low-g contrasts, lateral frontal recruitment is markedly similar in each case. Many previous experiments have shown these same frontal regions to be recruited by a broad range of different cognitive demands. The results suggest that "general intelligence" derives from a specific frontal system important in the control of diverse forms of behavior.

339 Morlet wavelet transform in EEG during perceptuo-motor tasks

339 Morlet wavelet transform in EEG during perceptuo-motor tasks

Deficit in learning of a motor skill requiring strategy, but not of perceptuomotor recalibration, with aging.

We investigated the effect of aging on different aspects of motor skill learning using two computer-presented perceptuomotor tasks. The relationship between visual and proprioceptive feedback was transformed in the first task, which was open to the formation and use of strategies. This task was designed to lead to perceptuomotor adaptation that was then measured by performance on a very similar second task that was not open to the use of strategy task. Older participants showed impaired learning of the strategic task but not of the nonstrategic task. This is in line with the suggestion that the effect of aging on learning and memory may be to reduce working memory resources.

P3B and positive slow wave following real and dummy feedback on arithmetic rule-learning and perceptuomotor tasks.

Event-related Potentials (ERPs) were recorded to feedback during a cognitively demanding, arithmetic rule-learning task and a relatively simple, skill-oriented, perceptuomotor task. For both tasks, a compound feedback display was employed. It consisted of numeric feedback information presented simultaneously with a red or green light (50% each) which indicated whether the numeric information was real (valid) or dummy (invalid). The task and feedback-validity manipulations showed a functional dissociation between the P3b (350-450 msec.) and a Positive Slow Wave (600-900-msec.). P3b was larger for real than for dummy feedback; Positive Slow Wave was larger for rule-learning than for perceptuomotor tasks.