Turning behavior in lamprey in response to descending unilateral commands: Experiments and modeling

摘要

Steering maneuvers in vertedbrates are characterized by asymmetric modulation of the cycle duration and the intensity of the symmetric rhythmic locomotor activity. In the lamprey in vitro model system, turns can be evoked by electrical skin stimuli applied to one side of the head, which give rise to descending unilateral excitatory commands. Turns are observed as increased activity on one side of the spinal cord, followed by a rebound on the other. We investigated the generation of turns in single-segment models if the lamprey locomotor Spinal network, and were able to reproduce all main experimental results. Sufficient mecha- Nisms to explain changes in the locomotor rhythm, including rebound, are asymmetric activa- Tion of crossing inhibitory neurons, accompanied by a calcium influx in these neurons.