Turning bias and lateral dominance in a sample of able-bodied and amputee participants

Neuropsychological Evidence Underlying Counterclockwise Bias in Running: Electroencephalography and Functional Magnetic Resonance Imaging Studies of Motor Imagery

We aimed to answer the question "why do people run the track counterclockwise (CCW)?" by investigating the neurophysiological differences in clockwise (CW) versus CCW direction using motor imagery. Three experiments were conducted with healthy adults. Electroencephalography (EEG) was used to examine hemispheric asymmetries in the prefrontal, frontal, and central regions during CW and CCW running imagery (n = 40). We also evaluated event-related potential (ERP) N200 and P300 amplitudes and latencies (n = 66) and conducted another experiment using functional magnetic resonance imaging (fMRI) (n = 30). EEG data indicated greater left frontal cortical activation during CCW imagery, whereas right frontal activation was more dominant during CW imagery. The prefrontal and central asymmetries demonstrated greater left prefrontal activation during both CW and CCW imagery, with CCW rotation exhibiting higher, though statistically insignificant, asymmetry scores than CW rotation. As a result of the fMRI experiment, greater activation was found during CW than during CCW running imagery in the brain regions of the left insula, Brodmann area 18, right caudate nucleus, left dorsolateral prefrontal cortex, left superior parietal cortex, and supplementary motor area. In the ERP experiment, no significant differences were found depending on direction. These findings suggest that CCW rotation might be associated with the motivational approach system, behavioral activation, or positive affect. However, CW rotation reflects withdrawal motivation, behavioral inhibition, or negative affect. Furthermore, CW rotation is understood to be associated with neural inefficiency, increased task difficulty, or unfamiliarity.

Gait asymmetry is associated with performance-based physical function among adults with lower-limb amputation

BACKGROUND

Adults with lower-limb amputation walk with an asymmetrical gait and exhibit poor functional outcomes, which may negatively impact quality-of-life.

OBJECTIVE

To evaluate associations between gait asymmetry and performance-based physical function among adults with lower-limb amputation.

METHODS

A cross-sectional study involving 38 adults with a unilateral transtibial (N = 24; 62.5 ± 10.5 years) or transfemoral amputation (N = 14; 59.9 ± 9.5 years) was conducted. Following gait analysis (capturing step length and stance time asymmetry at self-selected (SSWS) and fast walking speeds (FWS)), participants completed performance-based measures (i.e. Timed Up and Go (TUG), the 10-Meter Walk Test (10mwt), and the 6-Minute Walk Test (6MWT)).

RESULTS

Step length and stance time asymmetry (at SSWS and FWS) were significantly correlated with each performance-based measure (p < .001 to p = .035). Overall, models with gait measures obtained at SSWS explained 40.1%, 46.8% and 40.1% of the variance in TUG-time (p = .022), 10mwt-speed (p = .003) and 6MWT-distance (p = .010), respectively. Models with gait measures obtained at FWS explained 70.0%, 59.8% and 51.8% of the variance in TUG-time (p < .001), 10mwt-speed (p < .001), and 6MWT-distance (p < .001), respectively.

CONCLUSIONS

Increases in step length or stance time asymmetry are associated with increased TUG-time, slower 10mwt-speed, and reduced 6MWT-distance. Findings suggest gait asymmetry may be a factor in poor functional outcomes following lower-limb amputation.

A study of turn bias in people with idiopathic Parkinson's disease

The objective of the study is to explore whether people with Parkinson's disease (PwPD) display a preferential turn bias dependent upon disease asymmetry, and whether specific disease features predict turn bias. PwPD and age-matched controls were instructed to walk on an instrumented gait mat making "normal" turns. Trials were analyzed using Proto Kinetics Movement Analysis Software (PKMAS) and time-locked video recordings to obtain turn directionality and spatiotemporal turn measures. Turn bias was estimated using previously defined formulas. Seventy-two PwPD and 28 controls were included. One hundred percent of controls and 85% of PwPD had left turn bias. Turn bias was not significantly associated with age, gender, handedness, disease asymmetry, cognition, or disease severity. The Freezing of Gait Questionnaire (FOGQ) questions 5 and 6 showed linear-by-linear association with turn bias. In binary logistic and ordinal regression models, FOGQ question 6 (average duration of turn freezing) and turn width were predictive of turn bias. Rightward turns had greater frequency of freezing episodes. Turn bias in our PwPD cohort does not appear related to disease asymmetry or other disease features, except gait freezing. Whether freezing severity on turning leads to non-left turn bias or vice versa requires more focused studies. Physical therapy interventions targeting turning direction in PwPD could reduce freezing severity.

A novel virtual reality approach for functional lateralization in healthy adults

Functional lateralization relates to a natural asymmetry in the dominance right or left body side, and is a fundamental principle of the brain. The hemispheres of the brain control the contralateral body side, and show subtle, yet striking, anatomical asymmetries and functional lateralization. Innovative technologies, including Virtual Reality (VR), are entering the areas of experimental research, modeling and simulation related to the study of lateralization, with new perspectives of different applications in modern medical practice. Researchers/clinicians note that there are fewer VR studies with healthy participants, and which are important in evaluating/interpreting clinical outcomes, and testing the usefulness, limitations, and sensitivity of VR. The presented influence of the domination of upper/lower limbs on the performance of VR exercises was studied in healthy right-handed adults. Virtual testing sessions were performed independently with both/ dominant/ non-dominant hands, and the similar VR sessions were conduced on a Wii Balance Board (WBB) with the choice of body side, at different levels of the difficulty. The obtained results are consistent with other studies which show that cognitive-motor training in VR with the WBB platform is a very sensitive and promising tool for recognizing/assessing functional asymmetries of the right-left body side not only in disturbed lateralization, but also in the test training of healthy subjects.

Leg dominance as a determinant in laterality of lower extremity amputation in diabetic patients: retrospective study and literature review

Background/Aims

Diabetic patients with peripheral vascular manifestations often develop foot ulcers and sometimes have to undergo lower extremity amputation. This retrospective study investigated leg dominance and laterality of lower extremity amputation in diabetic, dysvascular amputees.

Methods

All patients who met the inclusion criteria had their medical records reviewed for their dominant side and a correlation with a side of amputation was analysed. This information is routinely obtained as part of the admission history. For the literature review, PubMed, Google Scholar, ScienceDirect and Cochrane Library were searched with no date restriction until February 2018. Relevant studies were included and analysed.

Results

Of all the patients (n=27), 16 had diabetes and of these, 12 (75%) had their dominant leg amputated.

Conclusions

The data and literature analysis suggest that diabetic, dysvascular patients' dominant legs may be at higher risk for amputation than the non-dominant side. Larger studies are needed to clarify the relationship between leg dominance and laterality of lower extremity amputation.

Four meta-analyses across 164 studies on atypical footedness prevalence and its relation to handedness

Human lateral preferences, such as handedness and footedness, have interested researchers for decades due to their pronounced asymmetries at the population level. While there are good estimates on the prevalence of handedness in the population, there is no large-scale estimation on the prevalence of footedness. Furthermore, the relationship between footedness and handedness still remains elusive. Here, we conducted meta-analyses with four different classification systems for footedness on 145,135 individuals across 164 studies including new data from the ALSPAC cohort. The study aimed to determine a reliable point estimate of footedness, to study the association between footedness and handedness, and to investigate moderating factors influencing footedness. We showed that the prevalence of atypical footedness ranges between 12.10% using the most conservative criterion of left-footedness to 23.7% including all left- and mixed-footers as a single non-right category. As many as 60.1% of left-handers were left-footed whereas only 3.2% of right-handers were left-footed. Males were 4.1% more often non-right-footed compared to females. Individuals with psychiatric and neurodevelopmental disorders exhibited a higher prevalence of non-right-footedness. Furthermore, the presence of mixed-footedness was higher in children compared to adults and left-footedness was increased in athletes compared to the general population. Finally, we showed that footedness is only marginally influenced by cultural and social factors, which play a crucial role in the determination of handedness. Overall, this study provides new and useful reference data for laterality research. Furthermore, the data suggest that footedness is a valuable phenotype for the study of lateral motor biases, its underlying genetics and neurodevelopment.

Impact of using immersive virtual reality over time and steps in the Timed Up and Go test in elderly people

Today, falls constitute a substantial health problem, especially in the elderly, and the diagnostic tests used by clinicians present often a low sensitivity and specificity. This is the case for the Timed Up and Go test which lacks contextualization with regard to everyday life limiting the relevance of its diagnosis. Virtual reality enables the creation of immersive, reproducible and secure environments, close to situations encountered in daily life, and as such could improve falling risk assessment. This study aims to evaluate the effect of immersive virtual reality by wearing a virtual reality headset with a non-disturbing virtual environment compared to real world on the Timed Up and Go test completion. Thirty-one elders (73.7 ± 9 years old) volunteered to participate in the study and the mean times and number of steps to complete a Timed Up and Go were compared in two conditions: actual-world clinical and virtual reality conditions. The results showed that the mean completion times and most of the mean number of steps of the Timed Up and Go in virtual reality condition were significantly different to those in clinical condition. These results suggest that there is a virtual reality effect and this effect is significantly correlated to the time taken to complete the Timed Up and Go. This information will be of interest to quantify the potential part of virtual reality effect on the motor control, measured in a virtual task using virtual controlled disturbances.

Childrens' left-turning preference is not modulated by magical ideation

The literature on human turning preferences is inconsistent. While the few studies with children below 14 years of age uniformly describe an overall left-turning (counterclockwise) tendency, a recent Internet study with more than 1500 adults found a right-sided (clockwise) bias. We set out to investigate spontaneous turning behaviour in children age 5-3 years and, based on neuropsychiatric work in adults, also explored a potential association with magical thinking. Findings indicated a clear left-turning preference, independent of a participant's sex and handedness. Whether a child responded a question about the existence of extrasensory communication in the affirmative or not was unrelated to direction and size of turning bias and lateral preference. Our results are consistent with a left-sided turning preference reported for children, but in opposition to the clockwise bias recently described in a large-scale study with adults. Whether they point to a maturational gradient in the preferred direction of spontaneous whole-body rotation or rather to a lack of comparability between measures used in observational versus Internet-based studies remains to be further investigated. Regarding a purported association between body turns and magical thinking, our study is preliminary, as only one single question was used to probe the latter.

The effect of stopping before turning on the direct observational measure of whole body turning bias

Turning bias, the preferential tendency to turn toward a given direction has been reported in both rodents and human participants. The observational gait method of determining turning bias in humans requires a stop prior to turning. This study removed the stop and hypothesised that turning bias would remain the same between stop and non-stop conditions if bias was solely under the control of neurochemical asymmetries. The results showed that statistically turning bias remained the same (to the left) regardless of method used but there was no agreement between the methods thus rejecting the hypothesis. It is likely that when not stopping biomechanical factors related to gait when turning influence the direction of turn rather than solely neurochemical asymmetries.

Absence of lateral navigational bias in young children

Previous research has shown American adults exhibit a systematic navigational bias to favor moving to the right when locomoting around obstacles and other people. To further investigate how and when the right-side navigational bias develops, the authors tested pre-school and early elementary school aged American children. Children ran down a straight pathway with an object at the center of the end-line. Unlike replicated findings with adults, both pre-school and early elementary school aged children showed no tendency to favor either side of the object. These findings support that the rightward navigation bias found in adults is not present in children up to elementary school, and suggest that the onset of bias occurs during the age range of late elementary or secondary school.

Parkinson's disease and segmental coordination during turning: I. Standing turns

OBJECTIVE

Many of the falls among people with Parkinson's disease (PD) occur during sudden, on-the-spot turning which requires systematic reorientation of axial segments towards the new direction. We examined whether a disturbance in the coordination of segmental reorientation is an important cause of turning difficulty in individuals with PD and is altered by dopaminergic medication.

METHODS

The sequence and timing of segmental reorientation during 45° and 90° on-the-spot turns was examined in fourteen individuals with PD while "off" and "on" medication and nineteen healthy controls (HC).

RESULTS

Regardless of the magnitude of the turn, HC reoriented their head, shoulder, and pelvis simultaneously followed by mediolateral foot displacement. PD patients displayed temporal coordination patterns similar to the HC. PD however, reduced the velocity and early magnitude of reorientation of each body segment which were both slightly improved by dopaminergic medication.

CONCLUSION

Our finding that the HC and PD patients turn en bloc when the turn is predictable and there are no time constraints shows that the strategy of en bloc turning is not wrong if the movement parameters are unconstrained. However, in real life situations, which usually require quick and unpredictable turns, the en bloc strategy may be unsafe and more likely to result in falls. While in such situations HC are able to change the strategy from en bloc to sequential segmental turning, PD patients may not be able to do so and continue to turn en bloc.

Lower limb preference on goal-oriented tasks in unilateral prosthesis users

The aim of this study was to determine lower limb preference in 31 prosthesis users and 19 able-bodied controls on 11 goal-oriented tasks in free-standing and supported conditions. The action leg used in 6 or more tasks was considered the preferred leg. We hypothesized that the prosthetic leg in amputees would be used as the preferred leg as often as the dominant leg in controls. For prosthesis users in the free-standing condition, 65% used the prosthetic leg as the preferred leg. This was significantly different (p<0.003) from able-bodied controls, where 100% used the dominant leg as the preferred leg. This discrepancy became even more pronounced in the supported condition and was overall more prevalent among those who used prosthesis for more than 10 years. These findings may have implications for therapy and gait training.

The temporal-spatial and ground reaction impulses of turning gait: is turning symmetrical?

This study had two aims. Firstly, to characterise the temporal-spatial and ground reaction impulse adjustments, compared to straight gait, required to complete step turns to the left and to the right and secondly, to assess if the turns were asymmetrical. Seven participants were instructed to perform 90 degrees step turns to the left and right. The actual angle turned was less for both turns (right 80.2+/-5.5 degrees , left 82.8+/-5.3 degrees ). Data were collected using a 7 camera VICON infra-red motion analysis system (120 Hz) and a Kistler force plate (600 Hz). Adjustments were made in the approach, turn and depart strides compared to straight gait. The mean velocity was significantly lower and the stride was significantly shorter in the approach stride before the turn (p<0.0125) compared to straight gait, indicating a possible feed-forward mechanism prior to turning. Velocity was significantly lower and the stride length significantly shorter during the depart stride (p<0.0125) compared to straight gait. Participants did not return to a normal pattern within one stride. For the turn step, the velocity, step length and step width were all significantly different (p<0.0125) compared to straight gait. The turning ground reaction impulses were significantly greater (p<0.0125) compared to straight gait, indicating a need for increased support, medial shift, braking and propulsion. The turns to the left and right were statistically asymmetrical (p<0.0125) in 11 of the 18 variables. However, impulses were generally symmetrical, which does not generally support the functional asymmetry theory, though the contributions to propulsion were significantly greater when turning from the dominant limb.

The influence of classical dance training on preferred supporting leg and whole body turning bias

A rightward turning bias has been more frequently noted during adult classical dance practice than during spontaneous rotations. Training could play a role in inducing a preferred direction. We observed the preferred direction for executing four spontaneous whole-body full turns (pirouettes), with eyes open or closed, in pre-pubertal untrained girls and classical dance students. Of untrained girls, 58% showed a leftward turning bias (LTB) and 42% a rightward turning bias (RTB), independently of vision, lateral preferences, and supporting leg. Only one dancer showed a consistent LTB while the majority showed a RTB, with a tendency to use the left leg to turn towards the right. These results suggest that the role of the vestibular and visual systems is minimal for untrained girls, and suggest a training influence for dancers. The dance students' choice of a supporting leg for turning may exploit some biomechanical properties facilitating the pirouette.

Local dynamic stability in turning and straight-line gait

Successful community and household ambulation require the ability to navigate corners and maneuver around obstacles, posing unique challenges compared to straight-line walking. The challenges associated with turning may contribute to an increased incidence of falling and the occurrence of fall-related injuries. A measure of stability applied to turning gait may be able to quantify a system's response to naturally occurring disturbances associated with turning and identify subjects at greater risk of falling. An index of stability has been used previously to assess the rate of kinematic separation (local dynamic stability) during straight-line gait. The purpose of this study was to determine if local dynamic stability during constant speed turning is reduced compared to straight-line treadmill walking. Maximum finite-time Lyapunov exponents (lambda) were used to estimate the local stability of able-bodied subjects' (n=19) sagittal plane hip, knee, and ankle trajectories for turning compared to straight-line walking at two different walking speeds. Turning lambda was greater than straight lambda for the hip, right knee, and ankle (p<0.05). Turning lambda for the left knee angle was similar to straight lambda. There were no differences in lambda between left and right limbs for the hip and ankle and also no differences between the inside and outside limbs during turning for all joints. These findings indicate able-bodied subjects' hip, right knee, and ankle kinematics are less locally stable while turning than walking in a straight line and may be used as a comparative tool for determining the efficacy of therapeutic interventions for mobility-impaired populations.