When analyzing te functions of the mammalian nervous system great difficulties are encountered due to the complexity of a system, with thousands of neurones involved in the regulation of even a simple reflex. To analyze the networks controlling different motor acts, specifically the control of locomotion, two "model systems" are used with relatively few neurons. The nervous system of the lamprey, a lower vertebrate, and the crayfish, a crustacean, have proven well suited for analyses at the level of "neurone-to-neurone interaction". The generality of the findings in these "model systems" will be assessed by comparing them with a relatively accessible, mammalian systems, the in vitro preparation of the neonate rat spinal cord generating locomotor-like activity.
The lamprey locomotor network is analyzed in the Stockholm laboratory In Marseille, the crayfish neuronal system is analysed as well as the mammalian spinal cord in vitro preparation has recently been developped. Both groups have over a number of years explored the neuronal bases of behaviour in these preparations and provided much of the knowledge currently available. A close interaction with an interchange of ideas and interpretations will in itself provide an obvious advantage for achieving a deeper understanding. The collaborative efforts will be focused on the following areas: (1) in Stockholm extensive computer simulations of the lamprey neuronal network generating locomotion have been performed with experimentally realistic neurons. The crayfish neuronal network will be simulated using the software currently available in the Stockholm laboratory. (2) 3-D characterization of the crayfish network interneurons with the confocal microscope available and developped in association with the Stockholm laboratory. (3) Sensory control of the locomotor network. Rather detailed information is now available of the network effects exerted by sensory afferents activated during ongoing movements. The crustacean (limb) and lamprey (trunk) sensory systems will be compared to understand this type of control system on the cellular level. This data will be used to further explore the mammalian control system, which has been analyzed previously on an organizational level by both Grillner and Orlovski independently. (4) The new in vitro preparation of the neonate rat spinal cord with fictive locomotion is analyzed in Marseille by using the knowledge developped in the lamprey spinal cord, and from studies in the cat.
Funding SchemeCSC - Cost-sharing contracts