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Dorsal spinal interneurons forming a primitive, cutaneous sensory pathway
W-C Li1, S R Soffe, Alan Roberts
1School of Biological Sciences, University of Bristol, Woodland Road, Bristol BS8 1UG, UK. wenchang.li@bristol.ac.uk
Journal of Neurophysiology
|March 19, 2004
Summary
Spinal cord sensory projection neurons, identified as dorsolateral interneurons in Xenopus tadpoles, activate swimming behaviors. These neurons transmit sensory information from skin touch to initiate or accelerate swimming.
Area of Science:
- Neuroscience
- Developmental Biology
- Comparative Physiology
Background:
- Mammalian sensory pathways rely on specific spinal interneurons originating from the roof-plate.
- Understanding the evolutionary origins of these pathways requires studying lower vertebrates.
Purpose of the Study:
- To investigate the presence and function of primitive sensory projection interneurons in a lower vertebrate model.
- To characterize the properties and connectivity of these neurons in the Xenopus tadpole spinal cord.
Main Methods:
- Utilized an immobilized Xenopus tadpole spinal cord preparation.
- Employed whole-cell patch recordings and dye filling for neuron identification.
- Analyzed electrophysiological properties and synaptic connections.
Main Results:
- Identified dorsolateral interneurons in the tadpole spinal dorsal horn.
- These neurons receive direct AMPA receptor-mediated excitation from cutaneous afferents.
- They excite spinal locomotor pattern generators via AMPA and NMDA receptors, projecting rostrally to the midbrain.
Conclusions:
- Spinal dorsolateral interneurons represent a primitive class of excitatory sensory projection neurons.
- These neurons are activated by ipsilateral cutaneous input and contribute to initiating/accelerating swimming.
- They provide a conserved mechanism for sensory-motor integration across vertebrates.