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Author |
Etienne, A.S.; Maurer, R.; Seguinot, V. |
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Title |
Path integration in mammals and its interaction with visual landmarks |
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Journal Article |
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Year |
1996 |
Publication |
The Journal of Experimental Biology |
Abbreviated Journal |
J Exp Biol |
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Volume |
199 |
Issue  |
Pt 1 |
Pages |
201-209 |
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Keywords |
Animals; Cognition/physiology; Cricetinae; Gerbillinae; Humans; Locomotion/*physiology; Mammals/*physiology; Mesocricetus; Mice; Proprioception/physiology; Rats; Visual Pathways/*physiology; Visual Perception/*physiology |
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Abstract |
During locomotion, mammals update their position with respect to a fixed point of reference, such as their point of departure, by processing inertial cues, proprioceptive feedback and stored motor commands generated during locomotion. This so-called path integration system (dead reckoning) allows the animal to return to its home, or to a familiar feeding place, even when external cues are absent or novel. However, without the use of external cues, the path integration process leads to rapid accumulation of errors involving both the direction and distance of the goal. Therefore, even nocturnal species such as hamsters and mice rely more on previously learned visual references than on the path integration system when the two types of information are in conflict. Recent studies investigate the extent to which path integration and familiar visual cues cooperate to optimize the navigational performance. |
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Laboratoire d'Ethologie, FPSE, Universite de Geneve, Carouge, Switzerland |
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0022-0949 |
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PMID:8576691 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
2758 |
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Author |
Witte, T.H.; Knill, K.; Wilson, A.M. |
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Title |
Determination of peak vertical ground reaction force from duty factor in the horse (Equus caballus) |
Type |
Journal Article |
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Year |
2004 |
Publication |
The Journal of Experimental Biology |
Abbreviated Journal |
J Exp Biol |
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Volume |
207 |
Issue |
Pt 21 |
Pages |
3639-3648 |
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Keywords |
*Acceleration; Animals; Biomechanics; Forelimb/physiology; *Gait; Hindlimb/physiology; Horses/*physiology; Locomotion/*physiology; Telemetry; Time Factors |
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Abstract |
Measurement of peak vertical ground reaction force (GRFz) from multiple limbs simultaneously during high-speed, over-ground locomotion would enhance our understanding of the locomotor mechanics of cursorial animals. Here, we evaluate the accuracy of predicting peak GRFz from duty factor (the proportion of the stride for which the limb is in contact with the ground). Foot-mounted uniaxial accelerometers, combined with UHF FM telemetry, are shown to be practical and accurate for the field measurement of stride timing variables, including duty factor. Direct comparison with the force plate produces a mean error of 2.3 ms and 3.5 ms for the timing of foot on and foot off, respectively, across all gaits. Predictions of peak GRFz from duty factor show mean errors (with positive values indicating an overestimate) of 0.8+/-0.04 N kg(-1) (13%; N=42; mean +/- S.E.M.) at walk, -0.3+/-0.06 N kg(-1) (3%; N=75) at trot, -2.3+/-0.27 N kg(-1) (16%; N=18) for the non-lead limb at canter and +2.1+/-0.7 N kg(-1) (19%; N=9) for the lead limb at canter. The substantial over- and underestimate seen at canter, in the lead and non-lead limbs, respectively, is attributed to the different functions performed by the two limbs in the asymmetrical gaits. The difference in load experienced by the lead and non-lead limbs decreased with increasing speed. |
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Structure and Motion Lab, The Royal Veterinary College, Hawkshead Lane, Hatfield, Hertfordshire, AL9 7TA, UK |
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0022-0949 |
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PMID:15371472 |
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Equine Behaviour @ team @ |
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3658 |
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Author |
Dutto, D.J.; Hoyt, D.F.; Clayton, H.M.; Cogger, E.A.; Wickler, S.J. |
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Title |
Moments and power generated by the horse (Equus caballus) hind limb during jumping |
Type |
Journal Article |
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Year |
2004 |
Publication |
The Journal of Experimental Biology |
Abbreviated Journal |
J Exp Biol |
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Volume |
207 |
Issue |
Pt 4 |
Pages |
667-674 |
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Keywords |
Animals; Biomechanics; Hindlimb/*physiology; Horses/*physiology; Locomotion/*physiology |
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Abstract |
The ability to jump over an obstacle depends upon the generation of work across the joints of the propelling limb(s). The total work generated by one hind limb of a horse and the contribution to the total work by four joints of the hind limb were determined for a jump. It was hypothesized that the hip and ankle joints would have extensor moments performing positive work, while the knee would have a flexor moment and perform negative work during the jump. Ground reaction forces and sagittal plane kinematics were simultaneously recorded during each jumping trial. Joint moment, power and work were determined for the metatarsophalangeal (MP), tarsal (ankle), tibiofemoral (knee) and coxofemoral (hip) joints. The hip, knee and ankle all flexed and then extended and the MP extended and then flexed during ground contact. Consistent with our hypothesis, large extensor moments were observed at the hip and ankle joints and large flexor moments at the knee and MP joints throughout ground contact of the hind limb. Peak moments tended to occur earlier in stance in the proximal joints but peak power generation of the hind limb joints occurred at similar times except for the MP joint, with the hip and ankle peaking first followed by the MP joint. During the first portion of ground contact (approximately 40%), the net result of the joint powers was the absorption of power. During the remainder of the contact period, the hind limb generated power. This pattern of power absorption followed by power generation paralleled the power profiles of the hip, ankle and MP joints. The total work performed by one hind limb was 0.71 J kg(-1). Surprisingly, the knee produced 85% of the work (0.60 J kg(-1)) done by the hind limb, and the positive work performed by the knee occurred during the first 40% of the take-off. There is little net work generated by the other three joints over the entire take-off. Velocity of the tuber coxae (a landmark on the pelvis of the animal) was negative (downward) during the first 40% of stance, which perhaps reflects the negative work performed to decrease the potential energy during the first 40% of contact. During the final 60% of contact, the hip, ankle and MP joints generate positive work, which is reflected in the increase of the animal's potential energy. |
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Department of Kinesiology and Health Promotion, California State Polytechnic University, Pomona, CA 91768, USA. ddutto@csupomona.edu |
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0022-0949 |
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Notes |
PMID:14718509 |
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Call Number |
Equine Behaviour @ team @ |
Serial |
3654 |
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