Implementation of specific motor expertise during a mental rotation task of hands

Exploring the role of disgust in hands and feet laterality judgement tasks

The hand laterality task (HLT) and the foot laterality task (FLT) are used to explore motor imagery, the ability to imagine an action without executing it. With our limbs, we interact with our body, with others, and with the environment. These contacts might cause negative feelings, such as disgust. Disgust is elicited by different drivers. For instance, body products and body envelope violations provoke disgust to avoid contaminations and to avoid damaging our bodies. However, not much is known about how disgust changes our motor imagery processes. In this study, we examined whether there is any difference in the ability to imagine hands and feet when these are emotionally charged with reminders of disgust. Thirty-six participants completed an online version of a classic (neutral) HLT and FLT and two emotionally charged (disgust) versions. Our findings show that when body parts are modified so that they elicit emotional processing, disgust is salient overall, rather than being salient specifically for actions. This is true for both our hands and our feet.

Does dynamic balance affect cube mental rotation task in badminton vs. volleyball female players?

BACKGROUND

Changing from a static to a dynamic balance condition could affect the performance of a cognitive task such as mental rotation. Thus, the main goal of this study is to investigate aspects of visual-spatial cognition between two non-contact sports (i.e., badminton and volleyball) in different upright conditions (i.e., standing position, frontal balance, and sagittal balance).

METHODS

Thirty-five volunteer female sports and physical education students, fourteen specialists in badminton and twenty-one specialists in volleyball agreed to participate in this study. Each of the assessments was a 3D cube mental rotation task with and/or without balance exercises (i.e., frontal and/or sagittal balance) on a wobble board. Five stimuli were used in the mental rotation task (i.e., 45°, 135°, 180°, 225° and 315° for objected-based cube condition with egocentric transformation) which included pairs of standard and comparison images.

RESULTS

The findings indicate that there was a notable decrease (p < 0.001; d = 1.745) in response time in both dynamic balance conditions (i.e., frontal and sagittal balance) compared to standing position condition. In addition, results revealed significant interaction between balance conditions (i.e., frontal and/or sagittal balance) and groups (i.e., badminton and volleyball) in the response time at 225° angle and in the error percentage.

CONCLUSIONS

In sum, dynamic balance is also an activity that involves mental manipulation of objects in 3D space, which can enhance badminton and volleyball female players' ability to rotate 3D cube stimuli.

More implicit and more explicit motor imagery tasks for exploring the mental representation of hands and feet in action

The mental representation of the body in action can be explored using motor imagery (MI) tasks. MI tasks can be allocated along a continuum going from more implicit to more explicit tasks, where the discriminant is the degree of action monitoring required to solve the tasks (which is the awareness of using the mental representation of our own body to monitor our motor imagery). Tasks based on laterality judgments, such as the Hand Laterality Task (HLT) and the Foot Laterality Task (FLT), provide an example of more implicit tasks (i.e., less action monitoring is required). While, an example of a more explicit task is the Mental Motor Chronometry task (MMC) for hands and feet, where individuals are asked to perform or imagine performing movements with their limbs (i.e., more action monitoring is required). In our study, we directly compared hands and feet at all these tasks for the first time, as these body districts have different physical features as well as functions. Fifty-five participants were asked to complete an online version of the HLT and FLT (more implicit measure), and an online version of the MMC task for hands and feet (more explicit measure). The mental representation of hands and feet in action differed only when the degree of action monitoring decreased (HLT ≠ FLT); we observed the presence of biomechanical constraints only for hands. Differently, when the degree of action monitoring increased hands and feet did not show any difference (MMC hands = MMC feet). Our results show the presence of a difference in the mental representation of hands and feet in action that specifically depends on the degree of action monitoring.

Body Schema as Assessed by Upper Limb Left/Right Judgment Tasks Is Altered in Stroke: Implications for Motor Imagery Training

BACKGROUND AND PURPOSE

Individuals with stroke often experience significant impairment of the upper limb. Rehabilitation interventions targeting the upper limb are typically associated with only small to moderate gains. The knowledge that body schema can be altered in other upper limb conditions has contributed to the development of tailored rehabilitation approaches. This study investigated whether individuals with stroke experienced alterations in body schema of the upper limb. If so, this knowledge may have implications for rehabilitation approaches such as motor imagery.

METHODS

An observational study performed online consisting of left/right judgment tasks assessed by response time and accuracy of: (i) left/right direction recognition; (ii) left/right shoulder laterality recognition; (iii) left/right hand laterality recognition; (iv) mental rotation of nonembodied objects. Comparisons were made between individuals with and without stroke. Secondary comparisons were made in the stroke population according to side of stroke and side of pain if experienced.

RESULTS

A total of 895 individuals (445 with stroke) participated. Individuals with stroke took longer for all tasks compared to those without stroke, and were less accurate in correctly identifying the laterality of shoulder (P < 0.001) and hand (P < 0.001) images, and the orientation of nonembodied objects (P < 0.001). Moreover, the differences observed in the hand and shoulder tasks were greater than what was observed for the control tasks of directional recognition and nonembodied mental rotation. No significant differences were found between left/right judgments of individuals with stroke according to stroke-affected side or side of pain.

DISCUSSION AND CONCLUSIONS

Left/right judgments of upper limb are frequently impaired after stroke, providing evidence of alterations in body schema. The knowledge that body schemas are altered in individuals with longstanding stroke may assist in the development of optimal, well-accepted motor imagery programs for the upper limb.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A394).

The effect of handedness on mental rotation of hands: a systematic review and meta-analysis

Body-specific mental rotation is thought to rely upon internal representations of motor actions. Handedness is a source of distinctly different motor experience that shapes the development of such internal representations. Yet, the influence of handedness upon hand mental rotation has never been systematically evaluated. Five databases were searched for studies evaluating hand left/right judgement tasks in adults. Two independent reviewers performed screening, data extraction, and critical appraisal. Eighty-seven datasets were included, with 72 datasets pooled; all had unclear/high risk of bias. Meta-analyses showed that right-handers were faster, but not more accurate, than left-handers at hand mental rotation. A unique effect of handedness was found on performance facilitation for images corresponding to the dominant hand. Meta-analyses showed that right-handers were quicker at identifying images of right hands than left hands-a dominance advantage not evident in left-handers. Differing hand representations (more lateralised hand dominance in right-handers) likely underpin these findings. Given potential differences between hand preference and motor performance, future research exploring their distinct contributions to mental rotation is warranted.

Performing the hand laterality judgement task does not necessarily require motor imagery

When people judge the laterality of rotated hand images, that is they perform the laterality judgement task (LJT), they are thought to use motor imagery. However, recent studies have suggested that its completion does not necessarily require the use of motor imagery. In this study, we investigated whether and how many people preferentially use motor imagery to perform the LJT in 37 healthy adults. We assessed the presence of behavioural features associated with motor imagery at the individual level, namely, the linear angle-response time (RT) relationship and the biomechanical constraints effect in the LJT and in the same-different judgement task (SDJT), in which people are not thought to use motor imagery. We found that at most 50% of participants showed both behavioural features in the palmar view condition of the LJT. Moreover, this proportion did not differ from that in the dorsal view condition of the LJT or that in both view conditions of the SDJT. These results demonstrate that a motor imagery-based strategy is not universally and specifically used to perform the LJT. Therefore, previous results of the LJT, in particular, regarding the biomechanical constraints effect, should be reinterpreted in light of our findings.

The Role of Time Constraints in Athletes' Egocentric Mental Rotation Performance

A selective effect of motor expertise on mental rotation is revealed by a high correlation between the performance of sports experts and ability on a mental rotation task. Evidence is shown by studies involving a spatial factor, such as image interference or a movement constraint. Alternatively, the time constraint, as another performance factor, is considered critical in the effect of sport expertise on mental rotation. Three experiments were conducted to examine the role of time constraints in egocentric mental rotation and the stage performance of athletes (divers) and nonathletes. In Experiment 1, an egocentric mental rotation task in an untimed condition was conducted, and reaction times (RTs), error rates (ERs), RTs at 0 °, and mental rotation speed were assessed. The results indicated that divers outperformed nonathletes in terms of RT, as well as perceptual and decision stages and rotation stages. Experiments 2 and 3 added a relative time constraint (subtracting 1/2 SD of all the subjects' RT from the M of each group's RT) and an absolute time constraint (subtracting 1/2 SD of all the subjects' RT from the M of all the subjects' RT) to the task, respectively. Superior RT and lower ER were observed for the divers in the time constraint condition. Moreover, the results illustrated that divers were faster than nonathletes in both stages when facing time pressure. In general, the present study has, for the first time, confirmed the role of time in the relationship between sports expertise and mental rotation.

Differential influence of habitual third-person vision of a body part on mental rotation of images of hands and feet

Left/right judgement (LRJ) tasks involve determining the laterality of presented hand or feet images. Allocentric images (third-person perspective; 3PP) take longer to identify than egocentric images (first-person perspective; 1PP), supporting that implicit motor imagery (IMI)-mentally manoeuvring one's body to match the shown posture-is used. While numerous cognitive processes are involved during LRJs, it remains unclear whether features of the individual (e.g., visual exposure, experience, task-dependent use) influence the type of recognition strategy used during LRJs (IMI versus non-IMI). To investigate whether an individual's routine visual exposure to hands/feet in 3PP disrupts the typical perspective-reaction time (RT) relationship in LRJs, hand therapists, podiatrists, and healthy controls completed online LRJ tasks of hand and feet images. A group-specific reduction in RT for only allocentric images would represent a switch to non-IMI strategies. The results show that routine visual exposure to feet in 3PP (podiatrists) results in quicker RTs only for allocentric images of feet, suggesting a switch from IMI to non-IMI (e.g., visual object-based recognition) strategies. In contrast, routine visual exposure to hands in 3PP (hand therapists) does not alter RT for allocentric images, suggesting maintenance of IMI. However, hand therapists have quicker RTs (vs other groups) for egocentric hand images, supporting enhanced sensorimotor processing for the hand, consistent with task-dependent use (precise hand use). Higher accuracy in health professionals (vs control) on both tasks supports enhanced body schema. Combined, this suggests that 3PP visual exposure to body parts and task-dependent use contribute to LRJ performance/recognition strategy.

(Lack of) Corticospinal facilitation in association with hand laterality judgments

In recent years, mental practice strategies have drawn much interest in the field of rehabilitation. One form of mental practice particularly advocated involves judging the laterality of images depicting body parts. Such laterality judgments are thought to rely on implicit motor imagery via mental rotation of one own's limb. In this study, we sought to further characterize the involvement of the primary motor cortex (M1) in hand laterality judgments (HLJ) as performed in the context of an application designed for rehabilitation. To this end, we measured variations in corticospinal excitability in both hemispheres with motor evoked potentials (MEPs) while participants (n = 18, young adults) performed either HLJ or a mental counting task. A third condition (foot observation) provided additional control. We hypothesized that HLJ would lead to a selective MEP facilitation when compared to the other tasks and that this facilitation would be greater on the right than the left hemisphere. Contrary to our predictions, we found no evidence of task effects and hemispheric effects for the HLJ task. Significant task-related MEP facilitation was detected only for the mental counting task. A secondary experiment performed in a subset of participants (n = 6) to further test modulation during HLJ yielded the same results. We interpret the lack of facilitation with HLJ in the light of evidence that participants may rely on alternative strategies when asked to judge laterality when viewing depictions of body parts. The use of visual strategies notably would reduce the need to engage in mental rotation, thus reducing M1 involvement. These results have implications for applications of laterality tasks in the context of the rehabilitation program.

Maturation and experience in action representation: Bilateral deficits in unilateral congenital amelia

Congenital unilateral absence of the hand (amelia) completely deprives individuals of sensorimotor experiences with their absent effector. The consequences of such deprivation on motor planning abilities are poorly understood. Fourteen patients and matched controls performed two grip selection tasks: 1) overt grip selection (OGS), in which they used their intact hand to grasp a three-dimensional object that appeared in different orientations using the most natural (under-or over-hand) precision grip, and 2) prospective grip selection (PGS), in which they selected the most natural grip for either the intact or absent hand without moving. For the intact hand, we evaluated planning accuracy by comparing concordance between grip preferences expressed in PGS vs. OGS. For the absent hand, we compared PGS responses with OGS responses for the intact hand that had been phase shifted by 180°, thereby accounting for mirror symmetrical biomechanical constraints of the two limbs. Like controls, amelic individuals displayed a consistent preference for less awkward grips in both OGS and PGS. Unexpectedly, however, they were slower and less accurate for PGS based on either the intact or the absent hand. We conclude that direct sensorimotor experience with both hands may be important for the typical development or refinement of effector-specific internal representations of either limb.