Optimization Reduces Knee-Joint Forces During Walking and Squatting: Validating the Inverse Dynamics Approach for Full Body Movements on Instrumented Knee Prostheses.

Because of the redundancy of our motor system, movements can be performed in many ways. While multiple motor control strategies can all lead to the desired behavior, they result in different joint and muscle forces. This creates opportunities to explore this redundancy, for example, for pain avoidance or reducing the risk of further injury.

Angular velocity around the longitudinal axis in combination with head movements of springboard divers during twisted somersaults.

The ability of springboard divers to perform and control difficult elements with multiple twisted somersaults before entering the water is of great interest for coaches and researchers. In order to produce twists within somersaults, divers use both 'contact' and 'aerial' techniques. After completing body axes rotations, head movements seem to be important, as they enable visual information in the air.

Planning Catching Movements: Advantages of Expertise, Visibility and Self-Throwing.

In a ball catching task, the catcher guides their hand to the ball's future trajectory. The hand may start to move even before the exact position is known, and the interceptive movement may be corrected online. Using a recent method for detecting the phases of catching movements we investigate how juggling experience, self-throwing, and delayed visibility of the ball, influence the timing of the hand's trajectory.

Single limb dynamics of jumping turns in dogs.

Maneuverability is of paramount importance for many animals, e.g., in predator-prey interactions.

Multimodal Sensorimotor Integration of Visual and Kinaesthetic Afferents Modulates Motor Circuits in Humans.

Optimal motor control requires the effective integration of multi-modal information. Visual information of movement performed by others even enhances potentials in the upper motor neurons through the mirror-neuron system. On the other hand, it is known that motor control is intimately associated with afferent proprioceptive information.

Gaze, head and eye movements during somersaults with full twists.

Somersaults with or without twists are the most important elements in sports such as gymnastics or trampolining. Moreover, to perform elements with the highest possible difficulty gymnasts should show good form and execution during the flight phase. In order to ensure perfect body control and a safe landing, gaze behavior has been proven to be crucial for athletes to orientate in the air.

Gaze behavior of trampoline gymnasts during a back tuck somersault.

In trampolining, gymnasts perform a variety of rotational jumping elements and have to demonstrate perfect control of the body during the flying phase. The performance of a somersault should include an opening phase, i.e.

Limb dynamics in agility jumps of beginner and advanced dogs.

A considerable body of work has examined the dynamics of different dog gaits, but there are no studies that have focused on limb dynamics in jumping. Jumping is an essential part of dog agility, a dog sport in which handlers direct their dogs through an obstacle course in a limited time. We hypothesized that limb parameters like limb length and stiffness indicate the skill level of dogs.

Opposite asymmetries of face and trunk and of kissing and hugging, as predicted by the axial twist hypothesis.

The contralateral organization of the forebrain and the crossing of the optic nerves in the optic chiasm represent a long-standing conundrum. According to the Axial Twist Hypothesis (ATH) the rostral head and the rest of the body are twisted with respect to each other to form a left-handed half turn. This twist is the result, mainly, of asymmetric, twisted growth in the early embryo.

Neck muscle responses of driver and front seat passenger during frontal-oblique collisions.

Background: Low-velocity motor vehicle crashes often lead to severe and chronic neck disorders also referred to as whiplash-associated disorders (WAD). The etiology of WAD is still not fully understood. Many studies using a real or simulated collision scenario have focused on rear-end collisions, whereas the kinematics and muscular responses during frontal-oblique collisions have hardly been investigated.

Analyzing the kinematics of hand movements in catching tasks-An online correction analysis of movement toward the target's trajectory.

Free, 3-D interceptive movements are difficult to visualize and quantify. For ball catching, the endpoint of a movement can be anywhere along the target's trajectory. Furthermore, the hand may already have begun to move before the subject has estimated the target's trajectory, and the subject may alter the targeted position during the initial part of the movement.

Vision adds to haptics when dyads perform a whole-body joint balance task.

When two or more people aim to produce joint action outcomes they need to coordinate their individual actions in space and time. Successful joint action performance has been reported to depend, among others, on visual and somatosensory information provided to the joint actors. This study investigated whether and how the systematic manipulation of visual information modulates real-time joint action when dyads performed a whole-body joint balance task.

Increased Throwing Accuracy Improves Children's Catching Performance in a Ball-Catching Task from the Movement Assessment Battery (MABC-2).

The Movement Assessment Battery for Children (MABC-2) is a functional test for identifying deficits in the motor performance of children. The test contains a ball-catching task that requires the children to catch a self-thrown ball with one hand. As the task can be executed with a variety of different catching strategies, it is assumed that the task success can also vary considerably.

Motor-Evoked Potentials in the Lower Back Are Modulated by Visual Perception of Lifted Weight.

Facilitation of the primary motor cortex (M1) during the mere observation of an action is highly congruent with the observed action itself. This congruency comprises several features of the executed action such as somatotopy and temporal coding. Studies using reach-grasp-lift paradigms showed that the muscle-specific facilitation of the observer's motor system reflects the degree of grip force exerted in an observed hand action.

An Internal Focus Leads to Longer Quiet Eye Durations in Novice Dart Players.

While the benefits of both an external focus of attention (FOA) and of a longer quiet eye (QE) duration have been well researched in a wide range of sporting activities, little is known about the interaction of these two phenomena and how a potential interaction might influence performance. It was this study's aim to investigate the interaction and potential effect on performance by using typical FOA instructions in a dart throwing task and examining both the QE and performance outcome. The results replicate neither the benefit of an external FOA nor the benefit of a longer QE duration.

Comment on "Cortical folding scales universally with surface area and thickness, not number of neurons".

The cerebrum of large mammals is convoluted, whereas that of small mammals is smooth. Mota and Herculano-Houzel (Reports, 3 July 2015, p. 74) inspired a model on an old theory that proposed a fractal geometry.

Perception of biological motion from size-invariant body representations.

The visual recognition of action is one of the socially most important and computationally demanding capacities of the human visual system. It combines visual shape recognition with complex non-rigid motion perception. Action presented as a point-light animation is a striking visual experience for anyone who sees it for the first time.

Decussation as an axial twist: A comment on Kinsbourne (2013).

One of the great mysteries of the brain, which has puzzled all-time students of brain form and function, is the contralateral organization of the forebrain and the crossings of its major afferent and efferent connections. As a novel explanation, two recent studies have proposed that the rostral part of the head, including the forebrain, is rotated by 180° with respect to the rest of the body (de Lussanet and Osse, 2012; Kinsbourne, 2013). Kinsbourne proposes one 180° turn while we consider the 180° being the result of two 90° turns in opposite directions.

Observing a movement correction during walking affects evoked responses but not unperturbed walking.

Seeing an action activates neurons in the premotor, motor, and somatosensory cortex. Since a significant fraction of these pyramidal neurons project to the spinal motor circuits, a central question is why we do not automatically perform the actions that we see. Indeed, seeing an action increases both cortical and spinal excitability of consistent motor patterns that correspond to the observed ones.

A computational model unifies apparently contradictory findings concerning phantom pain.

Amputation often leads to painful phantom sensations, whose pathogenesis is still unclear. Supported by experimental findings, an explanatory model has been proposed that identifies maladaptive reorganization of the primary somatosensory cortex (S1) as a cause of phantom pain. However, it was recently found that BOLD activity during voluntary movements of the phantom positively correlates with phantom pain rating, giving rise to a model of persistent representation.

Impaired visual perception of hurtful actions in patients with chronic low back pain.

Visually presented biological motion stimuli activate regions in the brain that are also related to musculo-skeletal pain. We therefore hypothesized that chronic pain impairs the perception of visually presented actions that involve body parts that hurt. In the first experiment, chronic back pain (CLBP) patients and healthy controls judged the lifted weight from point-light biological motion displays.

Brain activity for visual judgment of lifted weight.

It is well established that humans can recognize high-level aspects from point-light biological motion, such as gender and mood. If the task is to judge the manipulated weight we expected that sensorimotor regions should be recruited in the brain. Moreover, we have recently shown that chronic pain in a limb that is involved in the presented movement disturbs the weight judgment.

Influence of delayed muscle reflexes on spinal stability: model-based predictions allow alternative interpretations of experimental data.

Model-based calculations indicate that reflex delay and reflex gain are both important for spinal stability. Experimental results demonstrate that chronic low back pain is associated with delayed muscle reflex responses of trunk muscles. The aim of the present study was to analyze the influence of such time-delayed reflexes on the stability using a simple biomechanical model.

Phase-dependent reflex modulation in tibialis anterior during passive viewing of walking.

It is well established that reflexes are highly adaptive, as they depend both on our intention and on the active state of the muscles. Reflex gains change dynamically during actions such as walking and running, with the gain of cutaneous reflexes being increased at the end of the stance phase but decreased at the end of the swing phase in the tibialis anterior (TA) muscle. Reflex gains can even change during the mere observation of an action.

Depth perception from point-light biological motion displays.

Humans have a clear impression of facing in depth for point-light biological motion. However, this has not been measured systematically nor is it known on which cues humans rely for their judgment. In the present study subjects judged the facing orientation-in-depth of point-light displays.