Reorganization of the efferent activity of the locomotor generator controlling forelimb movements for electrical stimulation of the descending systems

The reorganization of the parameters of the efferent activity of the forelimb locomotion generator for electrical stimulation of the descending systems is determined in experiments on decerebrate immobilized cats. This generator is found to be characterized by a stable state at which the sum of influences of the signals from different descending systems on the generator is extremely limited. It is concluded that under the influence of these signals, the reorganizations of the activity of the locomotion generators of different limbs bring the motor program into a dynamic (or nearly dynamic) relationship with the supraspinal inflow, allowing for a sufficient limitation and balancing of the influences of the corresponding descending systems on the interneuronal networks determining the temporal and phase characteristics of the activity of these generators.A. A. Bogomolets Institute of Physiology, Ukrainian Academy of Sciences, Kiev. Translated from Neirofiziologiya, Vol. 23, No. 6, pp. 704–708, November–December, 1991.     

Locomotion induced by non-contingent intracranial electrical stimulation: Dopamine dependence and general characteristics

Intracranial self-stimulation (ICSS) is induced by delivery of electrical stimulation contingent upon a response such as bar pressing. This procedure has been widely used to investigate the brain reward system. Recent investigations, however, have noted that non-contingent electrical stimulation, also called experimenter applied stimulation (EAS), produces a unique set of locomotion behaviors that appear to be related to ICSS, and that these behaviors resemble locomotion similar to those elicited by dopamine enhancing drugs. However, little is known about the general characteristics of EAS-induced locomotion. While ICSS appears to be robust, long lasting, and highly rewarding in that the rat will invest vast amounts of time or energy to obtain the electrical stimulation, these parameters have not been explored for EAS. Moreover, the dopamine dependence of EAS-evoked locomotion is also not firmly established. Thus, the present study investigated dopamine dependence and general characteristics of the EAS-induced locomotion to determine its similarity to ICSS. Results suggested that motor and limbic systems were strongly activated by non-contingent EAS, and that the resulting locomotion was dopamine dependent, robust, continued across long time horizons, and was greater than that evoked by contingent electrical stimulation.     

Locomotion and adhesion of polymorphonuclear leukocytes effects of the supporting substratum

Contact angle measurements have been used to correlate surface hydrophobicity of a supporting substratum with adhesion and locomotion of polymorphonuclear leukocytes. The binding of human serum albumin, a well-known chemokinetic substance, to hydrophilic glass slides gave rise to hydrophobic surfaces with adhesive properties conducive, to cell polarization thus allowing cell locomotion. Parallel contact angle and cell adhesion measurements suggested that albumin modified the cellsubstratum interaction by increasing the van der Waals forces of attraction and reducing the electrostatic forces. By allowing cells to adhere to a hydrophobic surface (siliconized glass), it was found that protein could be omitted from in vitro test systems for leukocyte locomotion. It is suggested that quantitatively equal cell adhesion values may, depending on the type of attraction forces working in adhesion to the substratum, result in different locomotion patterns.     

Locomotion and adhesion of polymorphonuclear leukocytes. Effects of the supporting substratum

Contact angle measurements have been used to correlate surface hydrophobicity of a supporting substratum with adhesion and locomotion of polymorphonuclear leukocytes. The binding of human serum albumin, a well-known chemokinetic substance, to hydrophilic glass slides gave rise to hydrophobic surfaces with adhesive properties conductive to cell polarization, thus allowing cell locomotion. Parallel contact angle and cell adhesion measurements suggested that albumin modified the cell-substratum interaction by increasing the van der Waals forces of attraction and reducing the electrostatic forces. By allowing cells to adhere to a hydrophobic surface (siliconized glass), it was found that protein could be omitted from in vitro test systems for leukocyte locomotion. It is suggested that quantitatively equal cell adhesion values may, depending on the type of attraction forces working in adhesion to the substratum, result in different locomotion patterns.     

Deductive biology—Some cautious steps

For certain environments, the Darwinian model allows unique prediction of a function that any surviving system adapted to such an environment has to perform. This is the case for those environments that determine a “survival functional” of position in space-time of known shape. Purely temporal survival functionals can be distinguished from spatial and mixed ones. In each case, there exists an optimum path in combined physical and (reduced) metabolic space. Dependent on the admissible error, approximate solutions of different complexity are sufficient. All solutions possess an afferent, a central, and an efferent part. Within this general frame, specific, “probably simplest”, solutions are proposed for adaptive chemotaxis, insect locomotion, lower vertebrates locomotion, higher vertebrates locomotion, chronobiological systems, and immune systems, respectively—or rather, for the underlying functionals. Presented at the Society for Mathematical Biology Meeting, University of Pennsylvania, Philadelphia, August 19–21, 1976.     

A comparison of the locomotion of two desert-living Australian mammals, Antechinomys spenceri (Marsupialia: Dasyuridae) and Notomys cervinus (Rodentia: Muridae)

The locomotion of the marsupial, Antechinomys spenceri and the rodent, Notomys cervinus was studied by recording their tracks on long strips of smoked kymograph paper and by means of slow-motion cinematography. Although both animals occupy the same habitat and are similar in their general appearance, their methods of locomotion differ greatly, since Antechinomys leaps quadrupedally, while Notomys leaps bipedally at fast speeds and runs quadrupedally at slower speeds. The mean speed of both genera was 2.7 m/sec but the mean length of stride of Notomys was 51.2 cm compared with 44.3 cm in Antechinomys. The locomotion of the two Australian genera is compared with that of the North American rodents, Dipodomys and Microdipodops.
The significance of the different types of locomotion is discussed.     

On the applicability of the decentralized control mechanism extracted from the true slime mold: a robotic case study with a serpentine robot

A systematic method for an autonomous decentralized control system is still lacking, despite its appealing concept. In order to alleviate this, we focused on the amoeboid locomotion of the true slime mold, and extracted a design scheme for the decentralized control mechanism that leads to adaptive behavior for the entire system, based on the so-called discrepancy function. In this paper, we intensively investigate the universality of this design scheme by applying it to a different type of locomotion based on a 'synthetic approach'. As a first step, we implement this design scheme to the control of a real physical two-dimensional serpentine robot that exhibits slithering locomotion. The experimental results show that the robot exhibits adaptive behavior and responds to the environmental changes; it is also robust against malfunctions of the body segments due to the local sensory feedback control that is based on the discrepancy function. We expect the results to shed new light on the methodology of autonomous decentralized control systems.     

Travelling wave patterns in a model of the spinal pattern generator using spiking neurons

The aim of this study is to produce travelling waves in a planar net of artificial spiking neurons. Provided that the parameters of the waves – frequency, wavelength and orientation – can be sufficiently controlled, such a network can serve as a model of the spinal pattern generator for swimming and terrestrial quadruped locomotion. A previous implementation using non-spiking, sigmoid neurons lacked the physiological plausibility that can only be attained using more realistic spiking neurons. Simulations were conducted using three types of spiking neuronal models. First, leaky integrate-and-fire neurons were used. Second, we introduced a phenomenological bursting neuron. And third, a canonical model neuron was implemented which could reproduce the full dynamics of the Hodgkin–Huxley neuron. The conditions necessary to produce appropriate travelling waves corresponded largely to the known anatomy and physiology of the spinal cord. Especially important features for the generation of travelling waves were the topology of the local connections – so-called off-centre connectivity – the availability of dynamic synapses and, to some extent, the availability of bursting cell types. The latter were necessary to produce stable waves at the low frequencies observed in quadruped locomotion. In general, the phenomenon of travelling waves was very robust and largely independent of the network parameters and emulated cell types.     

Environmental and cow-related factors affect cow locomotion and can cause misclassification in lameness detection systems

To tackle the high prevalence of lameness, techniques to monitor cow locomotion are being developed in order to detect changes in cows’ locomotion due to lameness. Obviously, in such lameness detection systems, alerts should only respond to locomotion changes that are related to lameness. However, other environmental or cow factors can contribute to locomotion changes not related to lameness and hence, might cause false alerts. In this study the effects of wet surfaces, dark environment, age, production level, lactation and gestation stage on cow locomotion were investigated. Data was collected at Institute for Agricultural and Fisheries Research research farm (Melle, Belgium) during a 5-month period. The gait variables of 30 non-lame and healthy Holstein cows were automatically measured every day. In dark environments and on wet walking surfaces cows took shorter, more asymmetrical strides with less step overlap. In general, older cows had a more asymmetrical gait and they walked slower with more abduction. Lactation stage or gestation stage also showed significant association with asymmetrical and shorter gait and less step overlap probably due to the heavy calf in the uterus. Next, two lameness detection algorithms were developed to investigate the added value of environmental and cow data into detection models. One algorithm solely used locomotion variables and a second algorithm used the same locomotion variables and additional environmental and cow data. In the latter algorithm only age and lactation stage together with the locomotion variables were withheld during model building. When comparing the sensitivity for the detection of non-lame cows, sensitivity increased by 10% when the cow data was added in the algorithm (sensitivity was 70% and 80% for the first and second algorithm, respectively). Hence, the number of false alerts for lame cows that were actually non-lame, decreased. This pilot study shows that using knowledge on influencing factors on cow locomotion will help in reducing the number of false alerts for lameness detection systems under development. However, further research is necessary in order to better understand these and many other possible influencing factors (e.g. trimming, conformation) of non-lame and hence ‘normal’ locomotion in cows.     

Analysis of the mechanisms of interaction between generators of cyclic motor reactions and inputs from suprasegmental systems

The simulation mathematical model of neuronal generator systems was used for analyzing the interaction between inputs from descending (afferent) systems and generators of scratching (locomotion). The data obtained indicate that in cases when generators of cyclic motor reactions influence the effectiveness of synaptic transmission from the fibers of descending (or afferent) systems, the differences in the main characteristics of signals that are produced by these generators themselves and those that come to them are emphasized. These data allow us to conclude that the system supplying interaction between inputs from suprasegmental (afferent) fiber systems and generators of locomotion of scratching can be interpreted as an adaptive filter which processes spatial and temporal information coming to the spinal cord via different suprasegmental or primary afferent inputs and allows generators of cyclic motor reactions to correct their functioning in accordance with changing external conditions.Neirofiziologiya/Neurophysiology, Vol. 25, No. 3, pp. 211–215, May–June, 1993.     

How locomotion sub-functions can control walking at different speeds?

Inspired from template models explaining biological locomotory systems and Raibert׳s pioneering legged robots, locomotion can be realized by basic sub-functions: elastic axial leg function, leg swinging and balancing. Combinations of these three can generate different gaits with diverse properties. In this paper we investigate how locomotion sub-functions contribute to stabilize walking at different speeds. Based on this trilogy, we introduce a conceptual model to quantify human locomotion sub-functions in walking. This model can produce stable walking and also predict human locomotion sub-function control during swing phase of walking. Analyzing experimental data based on this modeling shows different control strategies which are employed to increase speed from slow to moderate and moderate to fast gaits.     

Brainstem pathways of the initiation of locomotion

Conclusion This overview of the brainstem pathways of the initiation of locomotion can be summarized as follows. There are locomotor regions (hypothalamic and mesencephalic) whose stimulation leads to the appearance of rhythmic stepping movements. These regions are nonuniform in composition: transient fibers as well as cells are found. The locomotor effects of electrical stimulation of these regions can largely be explained on the basis of the presence of efferent projections of the neurons to the medial reticular formation, as well as the activation of the transient fibers of other brain systems. The ventromedial parts of the reticular formation of the medulla oblongata, including areas of the macrocellular and (to a lesser extent) gigantocellular nuclei, form the final element in the suprasegmental system of locomotion initiation. The inconclusive data of different scientists who have used chemical microinjections into the locomotor regions make it impossible at present to specify precisely the neurochemical mechanisms underlying the initiation of locomotion. NMDA has been found to play an important role. The activation of the reticular formation during the triggering of stepping movements can take place either from the locomotor regions or by means of signals coming from the collaterals of the ascending sensory tracts. The wide spectrum of possible pathways of the initiation of locomotion apparently affords the organism a choice of ways by which to realize this process and is an important factor in its adaptation to its environment.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 23, No. 4, pp. 488–505, July–August, 1991.     

Estimating the speed of Drosophila locomotion using an automated behavior detection and analysis system

A fundamental phenotypic trait in Drosophila melanogaster is the speed of movement. Its quantification in response to environmental and experimental factors is highly useful for behavioral and neurological studies. Quantifying this behavioral characteristic in freely moving flies is difficult, and many current systems are limited to evaluating the speed of movement of one fly at a time or rely on expensive, time-consuming methods. Here, we present a novel signal processing method of quantifying the speed of multiple flies using a system with automatic behavior detection and analysis that we previously developed to quantify general activity. By evaluating the shape of the signal wave from recordings of a live and simulated single fly, a metric for speed of movement was found. The feasibility of using this metric to estimate the speed of movement in a population of flies was then confirmed by evaluating recordings taken from populations of flies maintained at two different temperatures. The results were consistent with those reported in the literature. This method provides an automated way of measuring speed of locomotion in a fly population, which will further quantify fly behavioral responses to the environment.     

Walk,swim or fly? Locomotor mode predicts genetic differentiation in vertebrates

Limited dispersal is commonly used to explain differences in diversification rates. An obvious but unexplored factor affecting dispersal is the mode of locomotion used by animals. Whether individuals walk, swim or fly can dictate the type and severity of geographical barriers to dispersal, and determine the general range over which genetic differentiation might occur. We collated information on locomotion mode and genetic differentiation (F_ST) among vertebrate populations from over 400 published articles. Our results showed that vertebrate species that walk tend to have higher genetic differentiation among populations than species that swim or fly. Within species that swim, vertebrates in freshwater systems have higher genetic differentiation than those in marine systems, which is consistent with the higher number of species in freshwater environments. These results show that locomotion mode can impact gene flow among populations, supporting at a broad‐scale what has previously been proposed at smaller taxonomical scales.     

Resting nymphal stages and the nature of individual development in trombiculid mites (Acariformes: Trombiculidae)

A morphological expression of quiescent nymphal instars (calyptostases) in trombiculid mites (Trombiculidae) is analysed. The analysis takes into consideration ontogenetic functions of different instars during the individual development of these mites, which includes an alternation of active and regressive quiescent instars. Cyclic start and blocking of different integumental differentiation programs in Trombiculidae is caused by the cyclic reduction and renewal of particular functions of respective instars, whereas internal organs of these mites do not transform significantly during the life cycle. The reduction of some functions, particularly the locomotion and feeding, in the quiescent nymphal instars with changed integumental function has an inevitable result in a complication and prolongation of the moulting process. The moulting of these instars begins at once after finishing the previous moulting cycle, i.e. it is realized in "automatic pattern" without the intermoult phase. In general, the organization of both quiescent proto- and tritonymph is the same, because it expresses concordant morphological correlations and synchronous reductions of certain functions and structures in these instars during the evolutionary process. At the same time, the trombiculid mites and, perhaps, other representatives of Parasitengona reveal the most generalized type of ontogenesis in Acariformes within the "alternating calyptostasy" phenomenon.     

Comparative analysis of the kinematics of hind limb movements in rats during different kinds of locomotion

A comparative analysis of phases of the locomotor cycle and the dynamics of changes in hind limb joint angles during swimming and stepping movements (on a treadmill), involving the fore- and hind limbs to different degrees, were undertaken in rats. Differences in the sequence and degree of changes in joint angles during locomotion of the types investigated were participation of the forelimbs in locomotion was found to be accompanied by more marked forward carrying of the hind limb. Dependence of the swing phase on duration of the cycle was observed and differences were found in the period of protraction of the limb (F period) during swimming and stepping. The role of central spinal processes and influences of peripheral afferents in the formation of different types of locomotion is discussed.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vol. 17, No. 2, pp. 189–198, March–April, 1985.     

Effects of ICV administration of the alpha1A-adrenoceptor antagonist 5-methylurapidil on concurrent measures of eating and locomotion after cocaine in the rat

Psychostimulants including amphetamine and cocaine induce locomotion and stereotypy and suppress eating. Although the capacity of cocaine to alter locomotion is usually viewed as related to dopamine neurotransmission, recent studies suggest that norepinephrine, acting through alpha1-adrenergic receptors (alpha1-ARs) can facilitate cocaine-stimulated locomotion. Of the three alpha1-AR subtypes (alpha(1A), alpha(1B), and alpha(1D)) identified to date, inactivation of the alpha(1B)-AR subtype diminishes cocaine-stimulated locomotion, whereas the impact of inactivation of the alpha(1A)-AR subtype on either eating or locomotion is unknown. In the present study, we assessed the relative impact of ICV administration of the alpha(1B)-AR antagonist 5-methylurapidil (5-MU) on cocaine-stimulated hyperlocomotion and hypophagia, using a concurrent method [Wellman, P.J., Ho, D.H., Davis, K.W., 2005. Concurrent measures of feeding and locomotion in rats. Physiology of Behavior 84 (5), 769-774.]. Rats were infused ICV with one of 3 doses of 5-MU (0, 3, or 30 nmol) and then injected (i.p.) with 0, 2.5, 5.0, 10.0, or 20.0 mg/kg cocaine HCl on each of five tests. Rats always received the same 5-MU dose, but a different cocaine dose on each trial. Feeding and locomotion were assessed concurrently during a 45-min postinjection period. Significant suppression of eating was noted at 2.5 mg/kg cocaine, a dose that does not alter forward locomotion in the rat. Administration of 5-MU did not alter locomotion in rats treated with saline, but did significantly increase baseline food intake. Neither cocaine-induced hypophagia nor hyperlocomotion was altered by ICV administration of 5-MU. These results suggest that the capacity of alpha1-AR agonists (e.g. phenylpropanolamine) to suppress eating may be related to activation of the alpha(1A)-AR subtype, whereas cocaine does not act through the alpha(1A)-AR subtype to suppress eating nor does this subtype modulate cocaine-induced hyperlocomotion.     

Reduction of biology to fundamental physics

It was shown that, while interpreting life as a physical phenomenon, fundamental physics allows for the following alternatives: relativity of animate and inanimate upon canonical transformations; the impossibility of the change from animate to inanimate state of isolated systems; the abandonment of attempts to reduce biology to the physics of isolated systems. The possibility of reducing biology to phenomenological physics was considered. A number of equations for the general phenomenological dynamics of density matrix was proposed.     

Motional instabilities in prey-predator systems

Differential fluxes can destabilize the locally stable stationary density distributions in interaction systems with diffusion, advection, and/or locomotion of chemical or biological species. By this method they can cause the formation of stationary or travelling spatial structures. Different scenarios of this general mechanism of spatio-temporal pattern formation in reaction-diffusion-advection systems will be demonstrated, using a simple two-species predator-prey system as an example model.