Outline

We use embryos and young tadpoles of the frog Xenopus to ask how nervous systems work at the cellular level, develop to form the correct connections, and are organised to allow animals to behave. Our methods include: analysis of behaviour, whole-cell patch recording, neuron imaging, network modelling. 

The young Xenopus tadpole provides a very simple model animal with limited behaviour. It can swim either spontaneously or when touched anywhere on the body. A pineal eye detects dimming which speeds up swimming. The tadpole stops swimming when the head bumps into solid objects and the tadpole sticks to things with mucus secreted by a cement gland on the head. If the tadpole is held it can make stronger struggling movements.

This simple behaviour is coordinated by an extremely basic nervous circuit with very few differentiated classes of neuron. For example, at the time of hatching, the spinal cord appears to have only 8 different classes of neuron but the spinal tadpole can still swim. Simple methods for testing the behavioural responses of normal and genetically manipulated tadpoles are given.

BBSRC Project: (2014 to 2017): "Cross-modality integration of sensory signals leading to initiation of locomotion”

In this project we are investigating how swimming is initiated in the hatchling Xenopus tadpole. The project is a collaboration with two other labs: Dr Wen-Chang Li in St Andrews University and Prof Roman Borisyuk in Plymouth University. Our aim is to understand how different sensory inputs converge in neurons in the hindbrain and lead to a decision to swim. We have preliminary evidence that the integration and decision to flex and swim are made on one class of neuron in the hindbrain.

As part of this project we have set up a website to explain our work in a way that everyone can understand (tadpoles.org.uk). We are especially keen to inform school children about tadpoles and how they can help us to understand all nervous systems. The website also has a game about tadpoles called Taddypoles (tadpoles.org.uk/games).

BBSRC Project (2009 to 2013): A neuronal network generating flexible locomotor behaviour in a simple vertebrate: studies on function and embryonic self-assembly

Other Projects:

• how simple rules may specify spinal network development.  This was the focus of a 3 year BBSRC supported project which started in 2009.
• role of electrical coupling between excitatory reticulospinal neurons controlling swimming
• role of lateral-line hair cells in mediating responses to water currents.
• Network reconfiguration for struggling
• Modelling the role of different neuron properties in spinal networks for swimming
• how feedback excitation allows prolonged swimming
• Roles of inhibitory interneurons and inhibition during swimming and struggling.
• Sensory control of tonic inhibitory pathways.
•  Role of inhibitory brainstem reticulospinal neurons in the control of swimming and function of stopping pathway
• Tadpole behaviour, role of pineal eye in control of swimming. Neuroanatomy of central neurons in brain and spinal cord.

Publications

Collaborators

• Dr Wen-Chang Li, (Royal Society University Research Fellow, School of Biology, University of St Andrews): Physiology and anatomy of CNS neurons.
• Prof Roman Borisyuk, (Centre for Theoretical and Computational Neuroscience, University of Plymouth): Modelling development of neuronal circuits.

Postgraduate Opportunities

 We are always looking for potential postgraduate students with a genuine interest in studying how the nervous system of frog tadpoles develops and functions. Contact Dr Steve Soffe or Prof Alan Roberts

Links to related sites

• Fetcho Zebrafish lab
• Lewis Zebrafish Lab
• Sillar Xenopus
• Spitzer Xenopus
• Xenbase