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From spontaneous motor activity to coordinated behaviour: a developmental model.

Marques HG, Bharadwaj A, Iida F - PLoS Comput. Biol. (2014)

Bottom Line: Our model is tested in a simulated musculoskeletal leg actuated by six muscles arranged in a number of different ways.Hopping is used as a case study of coordinated behaviour.In addition, our results show that our model can naturally adapt to different morphological changes and perform behavioural transitions.

View Article: PubMed Central - PubMed

Affiliation: Dept. of Mechanical and Process Engineering, ETH, Zurich, Switzerland.

ABSTRACT
In mammals, the developmental path that links the primary behaviours observed during foetal stages to the full fledged behaviours observed in adults is still beyond our understanding. Often theories of motor control try to deal with the process of incremental learning in an abstract and modular way without establishing any correspondence with the mammalian developmental stages. In this paper, we propose a computational model that links three distinct behaviours which appear at three different stages of development. In order of appearance, these behaviours are: spontaneous motor activity (SMA), reflexes, and coordinated behaviours, such as locomotion. The goal of our model is to address in silico four hypotheses that are currently hard to verify in vivo: First, the hypothesis that spinal reflex circuits can be self-organized from the sensor and motor activity induced by SMA. Second, the hypothesis that supraspinal systems can modulate reflex circuits to achieve coordinated behaviour. Third, the hypothesis that, since SMA is observed in an organism throughout its entire lifetime, it provides a mechanism suitable to maintain the reflex circuits aligned with the musculoskeletal system, and thus adapt to changes in body morphology. And fourth, the hypothesis that by changing the modulation of the reflex circuits over time, one can switch between different coordinated behaviours. Our model is tested in a simulated musculoskeletal leg actuated by six muscles arranged in a number of different ways. Hopping is used as a case study of coordinated behaviour. Our results show that reflex circuits can be self-organized from SMA, and that, once these circuits are in place, they can be modulated to achieve coordinated behaviour. In addition, our results show that our model can naturally adapt to different morphological changes and perform behavioural transitions.

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Convergence of all the reflex weights involving the Rectus Femoris motor element, .a) Reflex weights relative to the Ia -type afferents, and b) relative to the II-type afferents. For clarity, the raw data has been smoothed using a moving average filter with a window of
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pcbi-1003653-g005: Convergence of all the reflex weights involving the Rectus Femoris motor element, .a) Reflex weights relative to the Ia -type afferents, and b) relative to the II-type afferents. For clarity, the raw data has been smoothed using a moving average filter with a window of

Mentions: In Figure 5, we show how the connections between the motor element of the Rectus Femoris, and the sensor afferents of all the muscles, evolve during the passive stage. As can be seen the weights converge to rather stable values after around time at which each muscle has twitched once. When modifying the parameters in eq.5 our observations are consistent with those in the literature; lower values of () lead to a slower convergence of the weights, and values significantly higher () lead the weights to oscillate without any real convergence. We observe a similar convergence for the other muscles. These results indicate that spinal reflex circuits can be obtained from the self-organization of sensory and motor information induced by SMA.


From spontaneous motor activity to coordinated behaviour: a developmental model.

Marques HG, Bharadwaj A, Iida F - PLoS Comput. Biol. (2014)

Convergence of all the reflex weights involving the Rectus Femoris motor element, .a) Reflex weights relative to the Ia -type afferents, and b) relative to the II-type afferents. For clarity, the raw data has been smoothed using a moving average filter with a window of
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4109855&req=5

pcbi-1003653-g005: Convergence of all the reflex weights involving the Rectus Femoris motor element, .a) Reflex weights relative to the Ia -type afferents, and b) relative to the II-type afferents. For clarity, the raw data has been smoothed using a moving average filter with a window of
Mentions: In Figure 5, we show how the connections between the motor element of the Rectus Femoris, and the sensor afferents of all the muscles, evolve during the passive stage. As can be seen the weights converge to rather stable values after around time at which each muscle has twitched once. When modifying the parameters in eq.5 our observations are consistent with those in the literature; lower values of () lead to a slower convergence of the weights, and values significantly higher () lead the weights to oscillate without any real convergence. We observe a similar convergence for the other muscles. These results indicate that spinal reflex circuits can be obtained from the self-organization of sensory and motor information induced by SMA.

Bottom Line: Our model is tested in a simulated musculoskeletal leg actuated by six muscles arranged in a number of different ways.Hopping is used as a case study of coordinated behaviour.In addition, our results show that our model can naturally adapt to different morphological changes and perform behavioural transitions.

View Article: PubMed Central - PubMed

Affiliation: Dept. of Mechanical and Process Engineering, ETH, Zurich, Switzerland.

ABSTRACT
In mammals, the developmental path that links the primary behaviours observed during foetal stages to the full fledged behaviours observed in adults is still beyond our understanding. Often theories of motor control try to deal with the process of incremental learning in an abstract and modular way without establishing any correspondence with the mammalian developmental stages. In this paper, we propose a computational model that links three distinct behaviours which appear at three different stages of development. In order of appearance, these behaviours are: spontaneous motor activity (SMA), reflexes, and coordinated behaviours, such as locomotion. The goal of our model is to address in silico four hypotheses that are currently hard to verify in vivo: First, the hypothesis that spinal reflex circuits can be self-organized from the sensor and motor activity induced by SMA. Second, the hypothesis that supraspinal systems can modulate reflex circuits to achieve coordinated behaviour. Third, the hypothesis that, since SMA is observed in an organism throughout its entire lifetime, it provides a mechanism suitable to maintain the reflex circuits aligned with the musculoskeletal system, and thus adapt to changes in body morphology. And fourth, the hypothesis that by changing the modulation of the reflex circuits over time, one can switch between different coordinated behaviours. Our model is tested in a simulated musculoskeletal leg actuated by six muscles arranged in a number of different ways. Hopping is used as a case study of coordinated behaviour. Our results show that reflex circuits can be self-organized from SMA, and that, once these circuits are in place, they can be modulated to achieve coordinated behaviour. In addition, our results show that our model can naturally adapt to different morphological changes and perform behavioural transitions.

Show MeSH