Gait Acquisition Research Articles

Locomotor evolution in camels revisited: a quantitative analysis of pedal anatomy and the acquisition of the pacing gait

ABSTRACT Extant camelids (llamas and camels) are unique among wild mammals in their regular employment of a pacing gait. They also have a unique foot morphology, assumed to be an adaptation for this mode of locomotion: their feet are secondarily digitigrade, with the loss of hooves and the addition of a broad foot pad. We examined 22 measurements of the metapodials and phalanges of camelids and ruminants with bivariate and multivariate analyses, including 18 genera of extinct camelids from the Tertiary of North America. Extant camelids and ruminants were clearly distinguishable from each other. Most extinct camelids showed some morphological features typical of extant forms, five out of eighteen clustered with the extant camelids. Pacing may have evolved independently within the subfamilies Camelinae and Protolabinae. Additionally, evolutionary change towards a condition resembling that of extant camelids also occurred within the subfamilies Stenomylinae and Miolabinae. These parallel changes in camelid locomotor anatomy occurred in the late Oligocene or early Miocene, preceding the formation of widespread open grassland habitats in the late Miocene.

Involuntary rhythmic leg movements time-locked with the respiratory cycle

Involuntary rhythmic leg movements in childhood is an uncommon condition, the generators of which remain unknown. We report on a male 3 years of age with distinct features providing important clues concerning the location of one of these generators. At the age of 7 months, the previously healthy young male started with low frequency, rhythmic, and continuous (both during wakefulness and sleep) flexion/extension movements of the lower limbs. Movements interfered significantly with gait acquisition, and, despite normal cognitive development, he was able to walk only at age 2 years, 4 months. The neurologic examination revealed the absence of automatic stepping in the neonatal period, but was otherwise normal. A polygraphic electroencephalogram/electromyogram (EEG/EMG) recording, at the age of 2 years, 9 months, revealed rhythmic and synchronous legs with EMG activity at 0.5 Hz. A more complete polygraphic recording at the age of 3 years, 10 months, showed a lower frequency (0.35 Hz) for the movements, which were time-locked with the respiratory cycle. Magnetic resonance imaging (MRI) of the brain revealed an increased T 2 signal in the upper medulla-lower pons regions. The generator of the rhythmic legs movements is postulated to be the respiratory center, connecting with the reticulospinal projecting neurons through an aberrant pathway.

Compatibility of two 3D kinematic motion analysis systems during simultaneous real time gait acquisition

Compatibility of two 3D kinematic motion analysis systems during simultaneous real time gait acquisition

免疫ネットワークを用いた６脚歩行ロボットの歩容獲得

Recently, a strong demands of developing autonomous decentralized system has been arisen since systems have been increasing in their scale and complexity. On the other hand, biological systems can be said the ultimate decentral-ized systems, and are expected to provide feasible ideas to engineering fields. Among them immune systems work as on-line fault diagnosis systems by constructing self-nonself recognition networks. In this study, we try to apply this immunological self-nonself recognition networks to a gait acquisition of a 6-legged walking robot as a practical example.

Acquiring Adaptive Gaits For Many-Legged Robots by Reinforcement Learning.

A legged robot should be able to walk through an unknown environment and avoid unpredictable breakage. To realize this capability, the robot should learn to control its legs without being precisely informed of its internal and external environments. Since the worst condition is the situation where no environmental model is given and where only sensory input that informs the success or failure of walking is available, it is necessary to establish a learning mechanism to developing rules for walking under this situation. This paper proposes a reinforcement-learning-based method to realize this adaptive gait acquisition with minimal information. It was shown by computer simulations that the 6-and the 8-legged wall-climbing robots could successfully establish their gaits without any initial knowledge. It was also demonstrated that the simulated 8-legged robot could establish a new gait after one of its legs was broken.

A Review of Myotatic Reflexes and the Development of Motor Control and Gait in Infants and Children: A Special Communication

Although the mechanism of the phasic myotatic (or "stretch") reflex is well-known, the role of this reflex in adult gait remains speculative. The acquisition and development of locomotor skills with respect to the development of the myotatic reflex require further study in both healthy and neurologically impaired children. In this article, the well-documented properties of the healthy adult's myotatic reflex are compared with recent findings of the myotatic reflex in healthy infants and children and contrasted with reflex properties in patients with cerebral palsy. These data allow us to begin to characterize the emerging features of the stretch reflex in normal and pathological early development. From these data, we can begin to speculate about the relationship between changes in stretch reflexes and the acquisition of skillful movement and gait in early childhood.