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Spinobulbar neurons in lamprey: cellular properties and synaptic interactions
James F Einum1, James T Buchanan
1Department of Biological Sciences, Marquette University, Milwaukee, WI 53233, USA.
Journal of Neurophysiology
|July 14, 2006
Summary
Lamprey spinobulbar neurons project to the brain stem, relaying sensory and locomotor information. These neurons form excitatory and inhibitory connections with reticulospinal neurons, influencing motor networks.
Area of Science:
- Neuroscience
- Comparative Physiology
- Spinal Cord Research
Background:
- Spinal neurons projecting to the brain stem are crucial for sensory-motor integration.
- Lamprey nervous system offers a model for studying fundamental neural circuits.
Purpose of the Study:
- Characterize the properties of lamprey spinobulbar (SB) neurons.
- Investigate their axonal projections, dendritic morphology, and synaptic interactions.
Main Methods:
- In vitro electrophysiology in lamprey spinal cord preparations.
- Extracellular and intracellular recordings.
- Biocytin tracing for axonal and dendritic morphology.
- Paired recordings to assess synaptic connections.
Main Results:
- Identified 144 ascending spinal neurons with projections to the brain stem (SB neurons).
- SB neurons exhibit diverse axonal projections (ipsilateral, contralateral, bilateral) and dendritic distributions.
- SB neurons receive excitatory input from sensory neurons and reticulospinal neurons, and form both excitatory and inhibitory synapses onto reticulospinal neurons.
- SB neurons show rhythmic activity during fictive swimming.
Conclusions:
- SB neurons integrate sensory and locomotor network information.
- They play a significant role in transmitting neural signals from the spinal cord to the brain stem in lampreys.
- Synaptic interactions reveal complex feedback loops between SB and reticulospinal neurons.