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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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The reflex circuitry involving spindle afferents from primary () and secondary () fibres.Filled circles represent inhibitory connections and unfilled circles represent excitatory connections. From a qualitative point of view, the connectivity between both types of afferents (from different muscles) and the α-motoneuron of a given muscle is similar (see text). This figure has been adapted from [61].
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pcbi-1003653-g015: The reflex circuitry involving spindle afferents from primary () and secondary () fibres.Filled circles represent inhibitory connections and unfilled circles represent excitatory connections. From a qualitative point of view, the connectivity between both types of afferents (from different muscles) and the α-motoneuron of a given muscle is similar (see text). This figure has been adapted from [61].

Mentions: The mammalian circuitry mediating primary (type-Ia) and secondary (type-II) spindle afferents, and α-motoneurons is shown in Figure 15. Relative to the primary Ia afferent fibres [61], [62], the α-motoneurons of a given muscle receive direct excitatory connections both from afferents of homonymous () as well as of synergistic muscles (). The same muscle receives inhibitory connections from afferents of antagonist muscles through inhibitory interneurons (). From a functional point of view the connectivity of the secondary afferent is similar to that of the primary afferents, but in the former all the connections seem to be mediated via an additional excitatory interneuron [61].


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

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

The reflex circuitry involving spindle afferents from primary () and secondary () fibres.Filled circles represent inhibitory connections and unfilled circles represent excitatory connections. From a qualitative point of view, the connectivity between both types of afferents (from different muscles) and the α-motoneuron of a given muscle is similar (see text). This figure has been adapted from [61].
© Copyright Policy
Related In: Results  -  Collection

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

pcbi-1003653-g015: The reflex circuitry involving spindle afferents from primary () and secondary () fibres.Filled circles represent inhibitory connections and unfilled circles represent excitatory connections. From a qualitative point of view, the connectivity between both types of afferents (from different muscles) and the α-motoneuron of a given muscle is similar (see text). This figure has been adapted from [61].
Mentions: The mammalian circuitry mediating primary (type-Ia) and secondary (type-II) spindle afferents, and α-motoneurons is shown in Figure 15. Relative to the primary Ia afferent fibres [61], [62], the α-motoneurons of a given muscle receive direct excitatory connections both from afferents of homonymous () as well as of synergistic muscles (). The same muscle receives inhibitory connections from afferents of antagonist muscles through inhibitory interneurons (). From a functional point of view the connectivity of the secondary afferent is similar to that of the primary afferents, but in the former all the connections seem to be mediated via an additional excitatory interneuron [61].

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