Dr. HongYan Zhang
Vertebrate motor control networks initially assemble before movements begin and continue to develop until mature motor behaviour is in place. Many studies investigate locomotor control at different stages of development using model systems. However, how the spinal central pattern generators (CPGs) control rhythm generation still remains poorly understood. We use young Xenopus and zebrafish adult and larvae to study how their swimming CPGs work. Compared to mammalians, the networks controlling swimming in Xenopus tadpole and zebrafish are simpler and experimentally more accessible. At the time of hatching (stage 37/38) Xenopus tadpoles are only able to generate limited motor outputs including swimming. All types of swimming CPG neurons at this stage have been described in details. Just 24 hours later, at stage 42, a much more flexible swimming behaviour appears. The spinal network must have developed quickly to support this change, but the detailed mechanisms are largely unknown. The transparent feature and ease for genetic manipulation of zebrafish have provided huge advantages to explore spinal circuits. For example, specific CPG neuron subtypes (e.g. mnx1+ neurons) can be genetically marked, viewed directly, and genetically manipulated. Using these two model animals, we are able to monitor swimming activities (motor output) and simultaneously make in vivo patch-clamp recordings of individual neurons. This technique, together with other methods, enables us to investigate the following subjects: the development of spinal CPG neurons; how different rhythmic motor patterns are generated or modulated; and how spinal circuits recover following injuries. Results from simple animals like the Xenopus tadpole and zebrafish will provide critical insights into our understanding of more mature and complex mammalian motor systems.
The University of Edinburgh, Edinburgh Medical School
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