Rhythmic activity is widespread in nervous
systems, and plays a central role in motor pattern production and
sensory processing. These rhythms are generated endogenously by central
neural networks, and are thus an example of the nervous system's ability
to spontaneously create patterns. Network rhythmically has been extensively
studied, and we have a general understanding of the mechanisms underlying
it. However, we understand much less about its dynamic regulation
(how pattern period and phasing are controlled), and how these networks
interact with their peripheral effectors to continually generate behaviorally
appropriate motor outputs.
We study these issues in the pyloric
neuromuscular system of the lobster, Panulirus interruptus. The pyloric
network produces a 3 phase rhythmic neural output, and is composed
of ~14 neurons divided into 6 types. The lab has two main projects.
In the first, we have shown that the network maintains phase (neuron
burst durations and inter-neuronal delays proportionally change as
period changes) when cycle period is varied 3 to 5 fold; we are now
studying the cellular and network mechanisms underlying this ability.
Our second major interest is determining
the effect changing neural output has on muscle activity. We have
shown that pyloric muscles have very non-linear responses to changing
neural input (including transforming rhythmic input into tonic contraction),
and that each muscle responds differently to changes in neural input.
We are now investigating the cellular basis of these non-linear responses,
and describing their consequences on pyloric motor output.
