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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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Hinton diagrams of the reflex circuits obtained for the system with the modified .a) Connections involving Ia-type afferents and b) II-type afferents. Unfilled circles represent excitatory connections, and filled circles represent inhibitory connections. The red squares highlight the modified connections with respect to the default system.
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pcbi-1003653-g010: Hinton diagrams of the reflex circuits obtained for the system with the modified .a) Connections involving Ia-type afferents and b) II-type afferents. Unfilled circles represent excitatory connections, and filled circles represent inhibitory connections. The red squares highlight the modified connections with respect to the default system.

Mentions: The reflex circuits resulting from the modification of the geometrical path of the are shown in Figure 10. When compared with the circuits obtained for the default configuration (see Figure 4), one can observe that all the connections with the afferents () and motor elements () have been drastically altered (marked in red); the only exceptions are the homonymous connections (). In fact, these connections are now very similar to those of the which reflects the identical geometrical path followed by both muscles in the new leg configuration.


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

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

Hinton diagrams of the reflex circuits obtained for the system with the modified .a) Connections involving Ia-type afferents and b) II-type afferents. Unfilled circles represent excitatory connections, and filled circles represent inhibitory connections. The red squares highlight the modified connections with respect to the default system.
© Copyright Policy
Related In: Results  -  Collection

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

pcbi-1003653-g010: Hinton diagrams of the reflex circuits obtained for the system with the modified .a) Connections involving Ia-type afferents and b) II-type afferents. Unfilled circles represent excitatory connections, and filled circles represent inhibitory connections. The red squares highlight the modified connections with respect to the default system.
Mentions: The reflex circuits resulting from the modification of the geometrical path of the are shown in Figure 10. When compared with the circuits obtained for the default configuration (see Figure 4), one can observe that all the connections with the afferents () and motor elements () have been drastically altered (marked in red); the only exceptions are the homonymous connections (). In fact, these connections are now very similar to those of the which reflects the identical geometrical path followed by both muscles in the new leg configuration.

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