Transmitters, Membrane Properties and Network Circuitry in the Control of Locomotion in Lamprey
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Trends in Neurosciences
The lamprey brainstem and spinal cord can be maintained in vitro. It is a simple vertebrate preparation with comparatively few neurones. The neural correlates of different patterns of behaviour can be elicited in this in-vitro preparation. The subject of this review is the neuronal organization underlying locomotion, and, in particular, the role of different types of interneurones and their transmitters and mode of synaptic interaction. Excitatory amino acids, glycine, GABA, 5-HT, tachykinins and CCK have been implied as putative transmitters. The activation of one type of excitatory amino acid receptor, the NMDA receptor, can elicit TTX-resistant pacemaker-like membrane, potential oscillations. 5-HT can exert indirectly a potentiating effect via a depression of the postspike after-hyperpolarization (Ca2+-dependent potassium channels).