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PubMed1980

Localization of a descending pathway in the spinal cord which is necessary for controlled treadmill locomotion.

The spinal cord pathways which are important for controlled treadmill locomotion evoked by stimulation of the mesencephalic locomotor region (MLR) were investigated in cats subjected to subtotal spinal cord lesions at the C1-C2 level. Locomotion could be evoked following bilateral lesions of the dorsal columns, the dorsolateral funiculi, and the ventromedial funiculi, and after combined lesions of the dorsolateral and ventromedial funiculi, but not after bilateral lesions of the ventrolateral quadrant. Unilateral lesions of the ventrolateral quadrant abolished locomotion in the limbs is ipsilateral to the lesion. It is suggested that MLR stimulation may give rise to locomotion by activation of pontine and medullary reticulospinal pathways projecting through the ventrolateral quadrant.

Animals↗
PubMed1987

Monopodal fictive locomotion evoked by cervical cord stimulation in decerebrate cats.

Rhythmic motor discharges evoked by stimulation of the cervical lateral funiculus (LF) were compared with fictive forelimb locomotion evoked by stimulation of the mesencephalic locomotor region (MLR). In the same animals, extensor and flexor nerve discharges alternated in an essentially similar fashion on the LF-stimulated side, but on the contralateral side, such alternated activities were found only in the MLR-evoked fictive locomotion. Thus, it was concluded that the LF-evoked rhythm is monopodal fictive locomotion. Detailed analysis of temporal patterns of nerve discharges during monopodal fictive locomotion revealed 4 components of centrally programmed locomotor discharges for the elbow extensors; tonic back-ground discharges; gradually increasing excitation prior to flexor bursts; small excitation following flexor bursts; crossed excitation. These functional meanings are discussed.

Action Potentials↗
PubMed1984

The role of the nucleus reticularis tegmenti pontis in locomotion: a lesion study in the rat.

Bilateral anodal and cathodal electrolytic lesions of the nucleus reticularis tegmenti pontis (NRTP) increased forward locomotion in rats. The correlation between the magnitude of locomotion and percent of NRTP damage demonstrated that the more complete the NRTP destruction the greater the increase of locomotion. The lesioned rats exhibited at the same time low level rearing and running wheel activity as well as some lack of motor coordination during body balance tests. Taking into consideration the neural connections of the NRTP we suggest that disruption of NRTP-cerebellar pathways, rather than connection with forebrain structures is associated with the lesion-induced increase of forward locomotion.

Animals↗
PubMed1990

Posterior midbrain-induced locomotion.

The purpose of this study was to determine the nature of the neurochemical signals which impinge on the mesencephalic locomotor region (MLR) to produce locomotion in the rat. Injections of GABA antagonists into NADPH diaphorase-positive regions (PPN) were found to induce locomotion for short episodes (5-30 sec) which were repeated for several minutes (1-40 min). Such activity was blocked by injections of GABA and the GABA agonist, muscimol. Locomotion was induced by injection of substance P (SP), which also produced short, repeated episodes of locomotion. The more potent excitatory amino acid agonist, n-methyl-d-aspartic acid (NMDA), however, did produce dose-dependent, long-lasting (20 sec-5 min) locomotor episodes which were repeated over prolonged periods at the higher concentrations used (2-24 min). Additional injections of NMDA could drive stepping from a walk to a trot to a gallop. The effects of NMDA were blocked by injections of the excitatory amino acid antagonist, aminophosphonovalerionic acid (APV) (1-10 mM). Preliminary evidence suggests that carbachol (10-50 mM), a cholinergic agonist, inhibits NMDA-induced increases in muscle tone and episodes of stepping. The effect of carbachol was blocked by the cholinergic antagonist, atropine.

Animals↗
PubMed2005

Hippocampal theta activity related to elicitation and inhibition of approach locomotion.

This study determined if the hippocampal theta rhythm showed phase relationships or changes in amplitude and frequency with the onset of stimuli and locomotion in a task in which auditory cues initiated and suppressed approach locomotion. Rats with electrodes in the dorsal hippocampus lapped at a milk dipper and were presented a tone which predicted the delivery of a food pellet. In some trials the pellet cue tone was negated by 60-Hz clicks beginning 0.3 s after onset, and no pellet was delivered. A video capture system (20-ms sampling) synchronized to the hippocampal recording system (10-ms sampling) was used to determine the onset of locomotor approach to the pellet area. The findings failed to support proposals that phase-related mechanisms play a role in encoding and retrieval of movement-related information. Neither the pellet cue nor the negating cue reset the theta rhythm, and they did not produce differential evoked potentials. During milk lapping, theta amplitude increased in the 1/2s prior to all pellet cues regardless of their locomotor effect. Frequency also rose but only when a non-negated pellet elicited short-latency locomotion. During locomotor execution, theta peak amplitude peaked earlier than theta frequency by approximately one period. In general during performance of this task, increasing theta amplitude reflected a general preparation to process the cue and increasing theta frequency reflected the readiness to respond to the cue with locomotion.

Acoustic Stimulation↗
PubMed2005

Spatio-temporal analysis of locomotion in BALB/cByJ and C57BL/6J mice in different environmental conditions.

We analysed spatial and temporal characteristics of mouse locomotion and investigated whether mouse gait differed between strains and environments. To this end, we used two inbred strains of mice (BALB/cByJ and C57BL/6J) known for their contrasting inherent level of anxiety, in three different visual surroundings. The animal position was determined relative to each environment. Gait cycle, defined as the sequence of limb movements, was analysed relative to time. We also recorded spatial parameters of gait such as stride length, track width and footfall characteristics. These measures allowed us to obtain an accurate description of locomotion and to assess subtle modifications of the gait. We found that mice adjusted their position in space, posture and gait in order to either stabilize their body on the ground in a potentially unsafe environment, or to optimize propulsion and maneuverability in a safer location. In addition, the two strains of mice used different strategies, suggesting that the inherent level of emotionality may affect the organization of locomotion in mice. We further concluded that higher structures of the central nervous system are involved in the online control of locomotion.

Animals↗
PubMed2006

In humans Ib facilitation depends on locomotion while suppression of Ib inhibition requires loading.

The role of force feedback during gait is still a matter of debate. From work on cats, it is known that input from Golgi tendon organs from triceps surae does produce Ib facilitation during locomotion instead of autogenic inhibition. In humans, Stephens and Yang (Stephens, M.J., Yang, J.F., 1996. Short latency, non-reciprocal group I inhibition is reduced during the stance phase of walking in humans. Brain Res. 743, 24-31) found that voluntary contraction results in a reduction of Ib inhibition. During gait, they even observed Ib facilitation in a subset of subjects. This raises the question whether the crucial elements involved in these changes are either loading of the leg or locomotion. To examine this question, Ib reflexes were investigated during sitting, lying supine, lying supine with 300 N pressure applied to the foot sole, standing, and a rhythmic loading and unloading task called "reduced" gait. Ib inhibition was obtained during sitting and lying supine. This inhibition was significantly reduced or disappeared during standing and when lying supine but loaded. During the stance phase of "reduced" gait, the inhibition disappeared in eight subjects, and even a facilitation was observed in six subjects. It is concluded that the decrease in Ib inhibition from gastrocnemius to soleus occurs during a load-bearing condition and does not require locomotion. In contrast, Ib facilitation requires locomotion at least in a rudimentary form.

Electromyography↗
PubMed2005

Froude and the contribution of naval architecture to our understanding of bipedal locomotion.

It is fascinating to think that the ideas of two 19th century naval architects could offer useful insights for 21st century scientists contemplating the exploration of our planetary system or monitoring the long-term effects of a neurosurgical procedure on gait. The Froude number, defined as Fr = v2/gL, where v is velocity, g is gravitational acceleration and L is a characteristic linear dimension (such as leg length), has found widespread application in the biomechanics of bipedal locomotion. This review of two parameters, Fr and dimensionless velocity beta = (Fr)1/2, that have served as the criterion for dynamic similarity, has been arranged in two parts: (I) historical development, including the contributions by William Froude and his son Edmund, two ship designers who lived more than 130 years ago, the classic insights of D'Arcy Wentworth Thompson who, in his magnum opus On Growth and Form, espoused the connection between mathematics and biology, and the pioneering efforts of Robert McNeill Alexander, who popularised the application of Fr to animal locomotion; and (II) selected applications, including a comparison of walking for people of different heights, exploring the effects of different gravitational fields on human locomotion, establishing the impact of pathology and the benefits of treatment, and understanding the walking patterns of bipedal robots. Although not all applications of Fr to locomotion have been covered, the review offers an important historical context for all researchers of bipedal gait, and extends the idea of dimensionless scaling of gait parameters.

History, 19th Century↗
PubMed2005

Assessment of human locomotion by using an insole measurement system and artificial neural networks.

A new method for measuring and characterizing free-living human locomotion is presented. A portable device was developed to objectively record and measure foot-ground contact information in every step for up to 24h. An artificial neural network (ANN) was developed to identify the type and intensity of locomotion. Forty subjects participated in the study. The subjects performed level walking, running, ascending and descending stairs at slow, normal and fast speeds determined by each subject, respectively. The device correctly identified walking, running, ascending and descending stairs (accuracy 98.78%, 98.33%, 97.33%, and 97.29% respectively) among different types of activities. It was also able to determine the speed of walking and running. The correlation between actual speed and estimated speed is 0.98, p< 0.0001. The average error of walking and running speed estimation is -0.050+/-0.747 km/h (mean +/- standard deviation). The study has shown the measurement of duration, frequency, type, and intensity of locomotion highly accurate using the new device and an ANN. It provides an alternative tool to the use of a gait lab to quantitatively study locomotion with high accuracy via a small, light and portable device, and to do so under free-living conditions for the clinical applications.

Adolescent↗
PubMed2005

An analytical estimation of the energy cost for legged locomotion.

Legged locomotion requires the determination of a number of parameters such as stride period, stride length, order of leg movements, leg trajectory, etc. How are these parameters determined? It has been reported that the locomotor patterns of many legged animals exhibit common characteristics, which suggests that there exists a basic strategy for legged locomotion. In this study we derive an equation to estimate the cost of transport for legged locomotion and examine a criterion of the minimization of the transport cost as a candidate of the strategy. The obtained optimal locomotor pattern that minimizes the cost suitably represents many characteristics of the pattern observed in legged animals. This suggests that the locomotor pattern of legged animals is well optimized with regard to the energetic cost. The result also suggests that the existence of specific gait patterns and the phase transition between them could be the result due to optimization; they are induced by the change in the distribution of ground reaction forces for each leg during locomotion.

Animals↗
PubMedDate not supplied

Trunk muscle proprioceptive input assists steering of locomotion.

During locomotion, human subjects navigate in their environment and choose the direction by means of the internal representation of space that is continuously updated by sensory input. Aim of this study was to assess whether trunk proprioceptive information plays a role in the definition of the reference frame for orientation. Unilateral trunk muscle vibration was applied during locomotion along a straight path in seven subjects. Vibration was administered either from the onset or in the middle of a seven-step task, under eyes-open (EO) or blindfolded condition. The deviation of the walking trajectory was quantified by the distance of the seventh from the first foot print along the medio-lateral axis. Foot angles and stride lengths were computed for all foot-falls. Vibration produced a clear-cut deviation from the straight-ahead direction when delivered in the middle of blindfolded locomotion. With EO the deviation was much smaller. A mild deviation was obtained in blindfolded condition when vibration started at the onset of locomotion. All deviations from the straight-ahead were accompanied by coherent changes in foot orientation on the ground. Trunk proprioception plays a major role in the definition of locomotor trajectory. Trunk input seems to be weighted against vision and whole-body kinematic information.

Analysis of Variance↗
PubMed2004

Low micromolar concentrations of 4-aminopyridine facilitate fictive locomotion expressed by the rat spinal cord in vitro.

Upregulating the operation of spinal locomotor networks is one mechanism to restore, at least partially, lesion-impaired locomotion. We investigated if the K+ channel blocker 4-aminopyridine (4-AP) could facilitate spinal locomotor networks in addition to its well-known effect on motor nerve conduction. Fictive locomotor patterns were recorded from ventral roots (VRs) of the isolated spinal cord of the neonatal rat. 4-AP (0.1-50 microM) produced synchronous VR oscillations which did not develop into fictive locomotion. These oscillations had network origin, required intact glutamatergic transmission and were probably amplified via electrotonic coupling because of their depression by the selective gap junction blocker carbenoxolone. 4-AP (5 microM) slightly increased input resistance of lumbar motoneurons without affecting their action or resting potentials. Dorsal root (DR) evoked synaptic responses were enhanced (217 +/- 65%) by 5 microM 4-AP without changes in axon conduction. 4-AP (5 microM) accelerated fictive locomotion induced by N-methyl-d-aspartate (NMDA) and serotonin (5-HT) without altering cycle amplitude and facilitated the onset of fictive locomotion in the presence of sub-threshold concentrations of NMDA and 5-HT. Furthermore, in the presence of 4-AP, weak DR stimuli, previously insufficient to activate locomotor patterns, generated alternating VR discharges. Thus, although 4-AP per se could not directly activate the locomotor network of the spinal cord, it could strongly facilitate the locomotor program initiated by neurochemicals or electrical stimuli. These data suggest that the reported improvement by 4-AP in locomotor activity of spinal-injury patients may include activation of locomotor networks when low concentrations of this drug are administered in coincidence with appropriate stimuli.

4-Aminopyridine↗
PubMed2003

Microinjection of CART peptide 55-102 into the nucleus accumbens blocks amphetamine-induced locomotion.

The role played by the biologically active CART 55-102 peptide in NAcc AMPH induced locomotion was investigated. When microinjected alone into this site, none of the doses of CART 55-102 tested (0.1, 0.4, 1.0 or 2.5 microg/0.5 microl/side) produced effects on locomotion during a two-h test. However, when co-injected with AMPH (2.5 microg/0.5 microl/side) into the NAcc, moderately high (2.5 microg/side) and middle to high (0.4-2.5 microg/side) doses of CART 55-102 significantly attenuated the effects of AMPH on locomotion and rearing, respectively. These results indicate that CART peptides can exert an antagonistic effect on the generation of locomotion by AMPH in the NAcc.

Amphetamine↗
PubMed2004

Ontogeny of corticotropin-releasing factor effects on locomotion and foraging in the Western spadefoot toad (Spea hammondii).

We investigated the effects of corticotropin-releasing factor (CRF) and corticosterone (CORT) on foraging and locomotion in Western spadefoot toad (Spea hammondii) tadpoles and juveniles to assess the behavioral functions of these hormones throughout development. We administered intracerebroventricular injections of ovine CRF or CRF receptor antagonist alphahelical CRF((9-41)) to tadpoles and juveniles, and observed behavior within 1.5 h after injection. In both premetamorphic (Gosner stage 33) and prometamorphic (Gosner stages 35-37) tadpoles, CRF injections increased locomotion and decreased foraging. Injections of alphahelical CRF((9-41)) reduced locomotion but did not affect foraging in premetamorphic tadpoles, but dramatically increased foraging in prometamorphic tadpoles compared to both placebo and uninjected controls. Similarly, alphahelical CRF((9-41)) injections stimulated food intake and prey-catching behavior in juveniles. These results suggest that in later-staged amphibians, endogenous CRF secretion modulates feeding by exerting a suppressive effect on appetite. By contrast to the inhibitory effect of CRF, 3-h exposure to CORT (500 nM added to the aquarium water) stimulated foraging in prometamorphic tadpoles. These tadpoles also exhibited a CORT-mediated increase in foraging 6 h after CRF injection, which was associated with elevated whole-body CORT content and blocked by glucocorticoid receptor (GR) antagonist (RU486) injections. Thus, exogenous CRF influences locomotion and foraging in both pre- and prometamorphic tadpoles, but endogenous CRF secretion in relatively unstressed animals does not affect foraging until prometamorphic stages. Furthermore, the opposing actions of CRF and CORT on foraging suggest that they are important regulators of energy balance and food intake in amphibians throughout development.

Age Factors↗
PubMed1998

Depletion of dopamine in the nucleus accumbens prevents the generation of locomotion by metabotropic glutamate receptor activation.

The contribution of dopamine (DA) to the locomotion elicited by activation of nucleus accumbens (NAcc) metabotropic glutamate receptors (mGluRs) was investigated in the rat. Different groups of rats were pretreated with bilateral microinjections of either 6-hydroxydopamine (6-OHDA) or its vehicle into the NAcc and, on separate tests starting 10 days later, were tested for locomotion following microinjections (into the same site) of saline, the mGluR agonist, 1-aminocyclopentane-trans-1,3-dicarboxylic acid [(1S, 3R)-ACPD, 0.5 nmol/side] and amphetamine (AMPH, 6.8 nmol/side). DA levels at the microinjection sites were significantly depleted in 6-OHDA-treated rats (42-99% depletions compared to control values obtained in vehicle-treated rats). In contrast to the increased locomotion observed in non-lesioned animals, rats pretreated with 6-OHDA showed no increase in locomotor activity in response to (1S, 3R)-ACPD or AMPH when these were microinjected into the NAcc. The two groups of rats were indistinguishable when tested following NAcc saline. These findings suggest that, as with AMPH, enhanced locomotion produced by NAcc mGluR activation is dependent on intact DA neurotransmission in this site.

Amphetamine↗
PubMed1999

Sensitization of anorexia and locomotion induced by chronic administration of ephedrine in rats.

Repeated daily administration of the sympathomimetic agent ephedrine (EPH) leads to an augmentation (sensitization) of locomotor activity in rats. The present experiments examined the impact of repeated administration of the (-)- and (+)-EPH enantiomers on feeding in rats to assess whether the anorexic activity of EPH exhibits tolerance or sensitization during chronic exposure and whether the time course of these effects follows that observed in studies of locomotion. Adult male rats were injected once daily for 12 days with either vehicle or 5, 10 or 20 mg/kg (-)-EPH or with 10 or 20 mg/kg (+)-EPH. Horizontal locomotion and diet consumption were assessed for 60 min in an activity chamber. Suppression of feeding and the induction of locomotion were augmented over the first four days of administration of either 10 mg/kg or 20 mg/kg of the (-)-EPH enantiomer. In contrast, repeated administration of 20 mg/kg (+)-EPH resulted in augmentation of appetite suppression but not locomotion. These results confirm and extend the phenomenon of locomotor and feeding sensitization for ephedrine, but suggest that these effects may differ for the two enantiomers of ephedrine.

Animals↗
PubMed1996

Neurochemical bases of locomotion and ethanol stimulant effects.

The locomotor stimulant effect produced by alcohol (ethanol) is one of a large number of measurable ethanol effects. Ethanol-induced euphoria in humans and locomotor stimulation in rodents, a potential animal model of human euphoria, have long been recognized and the latter has been extensively characterized. Since the euphoria produced by ethanol may influence the development of uncontrolled or excessive alcohol use, a solid understanding of the neurochemical substrates underlying such effects is important. Such an understanding for spontaneous locomotion and for ethanol's stimulant effects is beginning to emerge. Herein we review what is known about three neurochemical substrates of locomotion and of ethanol's locomotor stimulant effects. Several lines of research have implicated dopaminergic, GABAergic, and glutamatergic neurotransmitter systems in determining these behaviors. A large collection of work is cited, which strongly implicates the above-mentioned neurotransmitter substances in the control of spontaneous locomotion. A smaller, but persuasive, body of evidence suggests that central nervous system processes utilizing these transmitters are involved in determining the effects of ethanol on locomotion. Particular emphasis has been placed on the mesolimbic ventral tegmental area to nucleus accumbens dopaminergic pathway, and on the ventral pallidum/substantia innominata, where GABA and glutamate have been found to play a role in altering the activity of this dopaminergic pathway. Research on ethanol and drug locomotor sensitization, increased responsiveness to the substance with repeated administration, is also reviewed as a process that may be important in the development of drug addiction.

Animals↗
PubMed1993

Finite state model of locomotion for functional electrical stimulation systems.

A finite state model of locomotion was developed to simplify a controller design for motor activities of handicapped humans. This paper presents a model developed for real time control of locomotion with functional electrical stimulation (FES) assistive systems. Hierarchical control of locomotion was adopted with three levels: voluntary, coordination and actuator level. This paper deals only with coordination level of control. In our previous studies we demonstrated that a skill-based expert system can be used for coordination level of control in multi-joint FES systems. Basic elements in this skill-based expert system are production rules. Production rules have the form of If-Then conditional expressions. A technique of automatic determination of these conditional expressions is presented in this paper. This technique for automatic synthesis of production rules uses fuzzy logic and artificial neural networks (ANN). The special class of fuzzy logic elements used in this research is called preferential neurons. The preferential neurons were used to estimate the relevance of each of the sensory inputs to the recognition of patterns defined as finite states. The combination of preferential neurons forms a preferential neural network. The preferential neural network belongs to a class of ANNs. The preferential neural network determined the set of finite states convenient for a skill-based expert system for different modalities of locomotion.

Ankle Joint↗