Institut de Neurosciences Cognitives et Intégratives d'Aquitaine (UMR5287)

Aquitaine Institute for Cognitive and Integrative Neuroscience

Université de Bordeaux

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CNRS Ecole Pratique des Hautes Etudes Université de Bordeaux

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Home > Teams > HYBRID ( De RUGY) > Themes

Theme 6: Hybrid crayfish

by Daniel Cattaert, Hybrid, Loïc Grattier - published on

Daniel Cattaert , Julien Bacqué-Cazenave

In order to study the processing of sensory feedback during ongoing movements, we developed a hybrid system comprising the thoracic ventral nerve cord with ganglia controlling legs and a simulation of the crayfish body.

In the in vivo situation, leg movements (produced in response to central commands) activate proprioceptors present at the various leg joints. This information is continuously integrated by the CNS to the ongoing command. Therefore, sensory information participates to dynamic processing of motor command. However, it is not possible to analyze this processing in vitro preparations of the CNS because no movement is produced.

To solve this problem, we developed a hybrid system in which a simulated body (comprising muscles, joints and segments whose properties are adjusted to biological measures in real crayfish) is connected to the in vitro preparation of the CNS. Connections are both motor (recorded motor nerve activities are sent to the simulation to activate the virtual muscles that act on virtual segments) and sensory (the virtual movements of the simulated leg produce changes in proprioceptor geometry that are used to apply the same deformations to the real biological proprioceptors dissected with the CNS).

In the experiment presented here, only one joint was tested in the hybrid system configuration. When the sensory-motor loop was open, i.e. when there is no connection from the motor nerve activity to the simulated muscles, the CNS generally presents a tonic activity.

When the loop is closed, the virtual leg that was horizontal moves downward due to gravity, and thereby induces a resistance reflex (activation of levator motor neurons ).

After a few seconds, the CNS engages a rhythmic motor activity that will last as long the hybrid system is in closed loop configuration. (Chung, B., Bacque-Cazenave, J., Cofer, D., Cattaert, D., and Edwards, D.H. 2014)