Peripheral feedback mechanisms acting on the central pattern generators for locomotion in fish and cat

1981 ◽  
Vol 59 (7) ◽  
pp. 713-726 ◽  
Author(s):  
O. Andersson ◽  
H. Forssberg ◽  
S. Grillner ◽  
P. Wallén
Keyword(s):  
Negative Feedback ◽  
Positive Feedback ◽  
Muscle Activity ◽  
Hind Limb ◽  
Central Pattern Generators ◽  
Feedback Mechanisms ◽  
Pattern Generators

The feedback mechanisms taking part in the control of locomotion in cat and fish are reviewed, particularly with regard to position- and movement-related feedback. It is shown that in both fish and cat there is a powerful position-dependent negative feedback which will act only in the position range where the muscle activity normally changes, e.g., from extensor to flexor activity. In addition, there is positive feedback in the middle of the movement range which will act in certain conditions, e.g., to promote and maintain flexor activity during the flexion of the hind limb.

scholarly journals Kinesin Kip2 enhances microtubule growth in vitro through length-dependent feedback on polymerization and catastrophe

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Anneke Hibbel ◽  
Aliona Bogdanova ◽  
Mohammed Mahamdeh ◽  
Anita Jannasch ◽  
Marko Storch ◽  
...  
Keyword(s):  
Motor Activity ◽  
Negative Feedback ◽  
Positive Feedback ◽  
Feedback Loop ◽  
Mitotic Spindles ◽  
Feedback Mechanisms ◽  
Biochemical Pathways ◽  
Mechanical Signaling ◽  
Microtubule Growth

The size and position of mitotic spindles is determined by the lengths of their constituent microtubules. Regulation of microtubule length requires feedback to set the balance between growth and shrinkage. Whereas negative feedback mechanisms for microtubule length control, based on depolymerizing kinesins and severing proteins, have been studied extensively, positive feedback mechanisms are not known. Here, we report that the budding yeast kinesin Kip2 is a microtubule polymerase and catastrophe inhibitor in vitro that uses its processive motor activity as part of a feedback loop to further promote microtubule growth. Positive feedback arises because longer microtubules bind more motors, which walk to the ends where they reinforce growth and inhibit catastrophe. We propose that positive feedback, common in biochemical pathways to switch between signaling states, can also be used in a mechanical signaling pathway to switch between structural states, in this case between short and long polymers.

Kinematics of locomotion by cats with a single hindlimb deafferented

1976 ◽  
Vol 39 (4) ◽  
pp. 667-678 ◽  
Author(s):  
M. C. Wetzel ◽  
A. E. Atwater ◽  
J. V. Wait ◽  
D. G. Stuart
Keyword(s):  
High Speed ◽  
Hind Limb ◽  
Stance Phase ◽  
Weight Bearing ◽  
Central Pattern Generators ◽  
Afferent Input ◽  
Normal Position ◽  
Pattern Generators ◽  
The Right ◽  
Stance Duration

1. Cinematographic measurements were made of stepping by cats on a motor-driven treadmill, both normally and 2-3 wk after deafferentation of the LH (left hind) limb. 2. After surgery, rhythmic cycling of the LH limb was blurred whether the leg was dragged, as by some cats, or if it was lifted from the surface, as by others. 3. Interlimb coordination was also blurred with respect to normal, although distinct rhythms were still seen. The RH (right hind) limb descended prematurely and, in the walk, had a prolonged stance phase. The interval between touchdowns of hind- and forelimb on the left side no longer equaled that interval on the right side. 4. As is true for a normal cat, if the LH-deafferented animal stumbled, relatively normal single and interlimb cyclings were regained after several strides. 5. By kinematic analysis, force deficits were found in the deafferented LH limb both during the stance, when extensors should be most active, and the swing, when the limb failed to attain a normal position above the surface of the belt. Weight bearing by the LF (left fore) limb was altered in some animals. 6. At high speed, mean LH stance duration failed to decrease in the normal fashion. Inter-limb timings were reset to greater extent than in low-speed walking, as if the LH limb was being used only minimally. 7. It was concluded that both rhythm and force were impaired in the deafferented limb and also in the three intact limbs, whose weight bearing had to compensate for LH weakness. The changed mechanical demands after surgery were probably met by interactions between the remaining afferent input and central pattern generators so as to secure fairly effective and expedient locomotion.

scholarly journals Sustained Responses to Brief Stimuli: Swimming in Xenopus Embryos

1984 ◽  
Vol 112 (1) ◽  
pp. 321-335
Author(s):  
ALAN ROBERTS ◽  
N. DALE ◽  
S. R. SOFFE
Keyword(s):  
Spinal Cord ◽  
Positive Feedback ◽  
Digital Computer ◽  
Computer Modelling ◽  
Central Pattern Generators ◽  
Motor Systems ◽  
Xenopus Embryos ◽  
Model Networks ◽  
Pattern Generators ◽  
Sustained Responses

Prolonged responses to brief triggering or releasing stimuli are commonplace in animal behaviour. The initiation of locomotion is an example but hypotheses for the central nervous origin of locomotory rhythms generally do not explain how activity is sustained. After a brief review, which suggests that positive feedback excitation could be involved, evidence from Xenopus embryos is considered. Here a brief skin stimulus can evoke long episodes of swimming even in curarized embryos. Feedback excitation provides a possible explanation for sustaining fictive swimming. This hypothesis is evaluated by simulation of simple neuronal networks using a physiologically realistic digital computer modelling programme. The results from simulations suggest that: (1) positive feedback excitation could sustain activity either in central pattern generators for locomotion or in postural motor systems and (2) that the model networks tested here are not appropriate to produce the pattern of motor output from the Xenopus embryo spinal cord.

Asymmetry of Hindlimb Muscle Activity and Cutaneous Reflexes After Tendon Transfers in Kittens

1999 ◽  
Vol 82 (6) ◽  
pp. 3392-3405 ◽  
Author(s):  
G. E. Loeb
Keyword(s):  
Muscle Activity ◽  
Central Pattern Generators ◽  
Mechanical Action ◽  
Emg Activity ◽  
Sham Operation ◽  
Cutaneous Reflexes ◽  
Tendon Transfers ◽  
Cutaneous Reflex ◽  
Hindlimb Muscle ◽  
Pattern Generators

The mechanical actions of various ankle muscles were changed by surgically crossing or transferring the tendons in kittens. After the kittens grew to adults, both hindlimbs were implanted with multiple electromyogram (EMG) recording and cutaneous nerve stimulation electrodes to compare the activity of altered and normal muscles. The tendon transfers showed a remarkable tendency to regrow toward normal or only slightly altered mechanical action. In these animals and in the sham-operation controls, the patterns of muscle activity and reflexes were symmetrical in corresponding muscles of the two legs, although they could differ substantially between animals, particularly for the cutaneous reflexes. Eleven animals had at least some persistent alterations in muscle action. Their cutaneous reflex patterns tended to be asymmetric, in some cases quite markedly. EMG activity during unperturbed locomotion and paw-shaking was more symmetrical, but there were some changes in altered muscles and their synergists. The central pattern generators for locomotion and paw-shaking and particularly for cutaneous reflexes during locomotion appear to be at least partially malleable rather than entirely hardwired. This may provide a tool for studying their development and spinal plasticity in general.

Effect of Central Pattern Generators Depended Different Walking Strategies on Gait Ability of Patients after Stroke

2017 ◽  
Vol 27 (2) ◽  
pp. 40
Author(s):  
Hua WU ◽  
Zaihua RU ◽  
Congying XU ◽  
Xudong GU ◽  
Jianming FU
Keyword(s):  
Central Pattern Generators ◽  
Pattern Generators

Rhythmic Pattern Generation in Invertebrates

2018 ◽  
pp. 390-400
Author(s):  
Astrid A. Prinz
Keyword(s):  
Central Pattern Generators ◽  
Pattern Generation ◽  
Rhythmic Pattern ◽  
Neuronal Circuit ◽  
Neuronal Circuits ◽  
Timing Circuit ◽  
Core Components ◽  
Pattern Generators

This chapter begins by defining central pattern generators (CPGs) and proceeds to focus on one of their core components, the timing circuit. After arguing why invertebrate CPGs are particularly useful for the study of neuronal circuit operation in general, the bulk of the chapter then describes basic mechanisms of CPG operation at the cellular, synaptic, and network levels, and how different CPGs combine these mechanisms in various ways. Finally, the chapter takes a semihistorical perspective to discuss whether or not the study of invertebrate CPGs has seen its prime and what it has contributed—and may continue to offer—to a wider understanding of neuronal circuits in general.

scholarly journals Suppression of personality variation in boldness during foraging in three-spined sticklebacks

2021 ◽  
Vol 75 (4) ◽  
Author(s):  
Hannah E. A. MacGregor ◽  
Aislinn Cottage ◽  
Christos C. Ioannou
Keyword(s):  
Negative Feedback ◽  
Risk Taking ◽  
Positive Feedback ◽  
Gasterosteus Aculeatus ◽  
Control Treatment ◽  
Refuge Use ◽  
Individual Level ◽  
Behavioural Type ◽  
State Behaviour

Abstract Consistent inter-individual variation in behaviour within a population, widely referred to as personality variation, can be affected by environmental context. Feedbacks between an individual’s behaviour and state can strengthen (positive feedback) or weaken (negative feedback) individual differences when experiences such as predator encounters or winning contests are dependent on behavioural type. We examined the influence of foraging on individual-level consistency in refuge use (a measure of risk-taking, i.e. boldness) in three-spined sticklebacks, Gasterosteus aculeatus, and particularly whether changes in refuge use depended on boldness measured under control conditions. In the control treatment trials with no food, individuals were repeatable in refuge use across repeated trials, and this behavioural consistency did not differ between the start and end of these trials. In contrast, when food was available, individuals showed a higher degree of consistency in refuge use at the start of the trials versus controls but this consistency significantly reduced by the end of the trials. The effect of the opportunity to forage was dependent on behavioural type, with bolder fish varying more in their refuge use between the start and the end of the feeding trials than shyer fish, and boldness positively predicted the likelihood of feeding at the start but not at the end of the trials. This suggests a state-behaviour feedback, but there was no overall trend in how bolder individuals changed their behaviour. Our study shows that personality variation can be suppressed in foraging contexts and a potential but unpredictable role of feedbacks between state and behaviour. Significance statement In this experimental study, we examined how foraging influences consistency in risk-taking in individual three-spined sticklebacks. We show that bolder individuals become less consistent in their risk-taking behaviour than shyer individuals during foraging. Some bolder individuals reinforce their risk-taking behaviour, suggesting a positive feedback between state and behaviour, while others converge on the behaviour of shyer individuals, suggesting a negative feedback. In support of a role of satiation in driving negative feedback effects, we found that bolder individuals were more likely to feed at the start but not at the end of the trials. Overall, our findings suggest that foraging can influence personality variation in risk-taking behaviour; however, the role of feedbacks may be unpredictable.

scholarly journals Bayesian analysis of time-varying interactions between stock returns and foreign equity flows

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Boubekeur Baba ◽  
Güven Sevil
Keyword(s):  
Stock Returns ◽  
Negative Feedback ◽  
Positive Feedback ◽  
Positive Response ◽  
Time Varying ◽  
Economic Uncertainty ◽  
Foreign Investors ◽  
New Findings ◽  
Net Flows ◽  
Feedback Trading

AbstractThis study discusses the trading behavior of foreign investors with respect to economic uncertainty in the South Korean stock market from a time-varying perspective. We employ a news-based measure of economic uncertainty along with the model of time-varying parameter vector autoregression with stochastic volatility. The empirical analysis reveals several new findings about foreign investors’ trading behaviors. First, we find evidence that positive feedback trading often appears during periods of high economic uncertainty, whereas negative feedback trading is exclusively observable during periods of low economic uncertainty. Second, the foreign investors’ feedback trading appears mostly to be well-timed and often leads the time-varying economic uncertainty except in periods of global crises. Third, lagged negative (positive) response of net flows to economic uncertainty is found to be coupled with lagged positive (negative) feedback trading. Fourth, the study documents an asymmetric response of foreign investors with regard to negative and positive shocks of economic uncertainty. Specifically, we find that they instantly turn to positive feedback trading after a negative contemporaneous response of net flows to shocks of economic uncertainty. In contrast, they move slowly toward negative feedback trading after a positive response of net flows to uncertainty shocks.

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