Institute for Mathematics and Its Applications
Sten Grillner, Nobel Institute for Neurophysiology
The lamprey is a primitive vertebrate with a nervous system that has the same basic plans as that of more advanced vertebrates. This nervous system can be maintained in vitro (isolated) for several days, and under these conditions the network underlying the locomotor behavior can be activated. This has permitted a detailed analysis of the network that generates the motor pattern and the structures that control the initiation and maintenance of the locomotor activity, as well as the sensory feedback control. The pattern generating part of the network is comprised of excitatory glutamatergic neurons and inhibitory glycinergic neurons. The network on the left and right sides of a segment are coupled with reciprocal inhibition. The membrane properties providing spike frequency adaptation and also post burst hyperpolarisation are important components in the control system. The knowledge has been developed through an interaction between experiments and detailed biophysical modelling. Recently the forebrain control system for goal-directed locomotor activity has been investigated, as well as the control of turning and maintenance of body orientation during movement.