Development of Posture and Locomotion in Free-ranging Primates

The brain requires internal or external reference frames to determine body orientation in space. These frames may change, however, to meet changing conditions. During quadrupedal overground locomotion by monkeys, the head rotates on a stabilized trunk during walking, but the trunk rotates on a stabilized head during galloping. Do the same movement patterns occur during in-place locomotion? Head and trunk pitch rotations were measured, and yaw and roll rotations estimated from cine films of three adult vervet monkeys (Cercopithecus aethiops L. 1758) walking and galloping quadrupedally on a treadmill. Head and trunk rotational patterns during treadmill walks were comparable to the patterns found during overground walks. The rotational velocities of these segments during both treadmill walks and gallops were also comparable to the velocities found during natural locomotion. By contrast, whereas head and trunk rotational patterns during treadmill gallops did occur that were comparable to the patterns practiced during overground gallops, a significantly different pattern involving large and simultaneous head and trunk rotations was more commonly observed. Simultaneous head and trunk rotations may be possible during treadmill gallops because the fixed visual surround is providing an adequate spatial reference frame. Alternatively, or in addition to this visual information, a re-weighting in other sensory modalities may be occurring. Specifically, the vestibular inputs used during overground locomotion to reference gravity or a gravity-derived vector may become less important than proprioceptive inputs that are using the treadmill belt surface as a reference. Regardless, the spatial reference frame being used, blinks that occur at specific times during the largest head yaw rotations may be necessary to avoid the initiation of unwanted and potentially destabilizing lateral sway brought on by sudden increases in optic flow velocity.

mentioning

confidence: 99%

Stabilization and mobility of the head and trunk in vervet monkeys(Cercopithecus aethiops) during treadmill walks and gallops

Dunbar

2004

“…Studies in the wild (Dunbar and Badam, 1998) and in captivity (Strait and Ross, 1999) reveal that the head in several primate species is commonly stabilized rotationally in space during natural and volitional quadrupedal locomotion. Preliminary evidence indicates, however, that the head frequently rotates through several degrees in the pitch and yaw planes during quadrupedal walks but rotates through less than 20°in the pitch plane and only minimally in any other plane during gallops (Dunbar and Badam, 1998).…”

mentioning

confidence: 99%

Stabilization and mobility of the head and trunk in wild monkeys during terrestrial and flat-surface walks and gallops

Dunbar

Badam

Hallgrímsson

et al. 2004

The vestibular system has been hypothesized to play a critical role in both gaze stabilization and the perception of spatial orientation. Morphological studies of the vestibular apparatus have included investigations of otolith organ and semicircular canal orientation, canal arc size and scaling to body size, and/or how vestibular design relates to control of gaze, head and neck orientation, and balance during posture and locomotion (e.g. Blanks et al., 1985;Graf et al., 1997;Jones and Spells, 1963;Matano et al., 1985Matano et al., , 1986Spoor and Zonneveld, 1998;Spoor et al., 1994). Physiological studies This study investigated the patterns of rotational mobility (>20°) and stability (≤20°) of the head and trunk in wild Indian monkeys during natural locomotion on the ground and on the flat-topped surfaces of walls. Adult hanuman langurs (Semnopithecus entellus) and bonnet macaques (Macaca radiata) of either gender were cine filmed in lateral view. Whole-body horizontal linear displacement, head and trunk pitch displacement relative to space (earth horizontal), and vertical head displacement were measured from the cine films. Head-to-trunk pitch angle was calculated from the head-to-space and trunk-tospace measurements. Locomotor velocities, cycle durations, angular segmental velocities, mean segmental positions and mean peak frequencies of vertical and angular head displacements were then calculated from the displacement data. Yaw rotations were observed qualitatively. During quadrupedal walks by both species, the head was free to rotate in the pitch and yaw planes on a stabilized trunk. By contrast, during quadrupedal gallops by both species, the trunk pitched on a stabilized head. During both gaits in both species, head and trunk pitch rotations were symmetrical about comparable mean positions in both gaits, with mean head position aligning the horizontal semicircular canals near earth horizontal. Head pitch direction countered head vertical displacement direction to varying degrees during walks and only intermittently during gallops, providing evidence that correctional head pitch rotations are not essential for gaze stabilization. Head-to-space pitch velocities were below 350·deg.·s -1 , the threshold above which, at least among humans, the vestibulo-ocular reflex (VOR) becomes saturated. Mean peak frequencies of vertical translations and pitch rotations of the head ranged from 1·Hz to 2·Hz, a lower frequency range than that in which inertia is predicted to be the major stabilizer of the head in these species. Some variables, which were common to both walks and gallops in both species, are likely to reflect constraints in sensorimotor control. Other variables, which differed between the two gaits in both species, are likely to reflect kinematic differences, whereas variables that differed between the two species are attributed primarily to morphological and behavioural differences. It is concluded that either the head or the trunk can provide the nervous system with a reference frame for spatial orientation...

“…An ontogenetic transition in limb phase preference has also been demonstrated for other mammals such as rodents (Eilam, 1997), cats (Peters, 1983) and primates (Hildebrand, 1967;Rollinson and Martin, 1981;Hurov, 1982;Vilensky and Gankiewicz, 1989;Nakano, 1996;Dunbar and Badam, 1998;Shapiro and Raichlen, 2005;Shapiro and Raichlen, 2006). These transitions are in part associated with neurological maturation (Muir, 2000), but there is also evidence that limb phases preferred by juveniles compensate for growth-related changes in limb proportions or the position of the body's center of mass (Hildebrand, 1967;Rollinson and Martin, 1981;Peters, 1983;Blumberg-Feldman and Eilam, 1995;Shapiro and Raichlen, 2006).…”

Section: Age Affects Quadrupedal Kinematics In P Brevicepsmentioning

confidence: 79%

“…DSDC walking, along with a complex of other kinematic features, has been associated with adaptation to a small branch arboreal niche (Larson, 1998;Cartmill et al, 2002;Lemelin et al, 2003;Cartmill et al, 2007), but the potential biomechanical advantage provided by DSDC for walking on small diameter substrates remains unclear (Stevens, 2006;Shapiro and Raichlen, 2007;Stevens, 2007;Wallace and Demes, 2008), and adult sugar gliders prefer LSDC walking, even on very narrow substrates (Shapiro and Young, 2010). In addition, infant primates have been shown to differ from adults in their gait preferences as a means to enhance stability or reduce limb interference (Hildebrand, 1967;Rose, 1977;Rollinson and Martin, 1981;Hurov, 1982;Vilensky and Gankiewicz, 1989;Nakano, 1996;Dunbar and Badam, 1998;Shapiro and Raichlen, 2005;Shapiro and Raichlen, 2006). Ontogenetic transitions in limb phase have also been documented for other mammals such as cats (Peters, 1983) and rodents (Eilam, 1997).…”

Section: Functional Rationale and Predictions For Kinematic Variablesmentioning

confidence: 99%

Kinematics of quadrupedal locomotion in sugar gliders (Petaurus breviceps): effects of age and substrate size

Shapiro

Young

2012

SUMMARY Arboreal mammals face unique challenges to locomotor stability. This is particularly true with respect to juveniles, who must navigate substrates similar to those traversed by adults, despite a reduced body size and neuromuscular immaturity. Kinematic differences exhibited by juveniles and adults on a given arboreal substrate could therefore be due to differences in body size relative to substrate size, to differences in neuromuscular development, or to both. We tested the effects of relative body size and age on quadrupedal kinematics in a small arboreal marsupial (the sugar glider, Petaurus breviceps; body mass range of our sample 33-97 g). Juvenile and adult P. breviceps were filmed moving across a flat board and three poles 2.5, 1.0 and 0.5 cm in diameter. Sugar gliders (regardless of age or relative speed) responded to relative decreases in substrate diameter with kinematic adjustments that promote stability; they increased duty factor, increased the average number of supporting limbs during a stride, increased relative stride length and decreased relative stride frequency. Limb phase increased when moving from the flat board to the poles, but not among poles. Compared with adults, juveniles (regardless of relative body size or speed) used lower limb phases, more pronounced limb flexion, and enhanced stability with higher duty factors and a higher average number of supporting limbs during a stride. We conclude that although substrate variation in an arboreal environment presents similar challenges to all individuals, regardless of age or absolute body size, neuromuscular immaturity confers unique problems to growing animals, requiring kinematic compensation.