Neural and molecular control of motor circuits











       


We are also interested in how patterns of motor activity are generated and controlled. A behavior we have particularly focused on is egg-laying. Since the motorneurons that drive egg-laying are functionally complex, making use of at least two neuromodulators (serotonin and a neuropeptide) and one fast neurotransmitter (acetylcholine), egg-laying behavior provides an accessible model for how neumodulators control the functional states of complex synapses. Analysis of data obtained with an automated tracking system demonstrated that nematode egg-laying could be modeled as a novel random process in which animals fluctuate between discrete behavioral states: an inactive state and an active state. Using a combination of genetics, behavioral analysis, and in vivo neuroimaging, we are probing the molecular and neural basis for these behavioral states and attempting to understand mechanisms underlying the generation of patterned motor activity.
       











       




 



       



Movies:




       



A worm laying eggs






       
           




       











       
Vulval muscles contracting--calcium influx




       











       
           




       











       

   

Recent papers:

Egg-laying:

Shyn SI, Kerr R, Schafer WR. (2003) "Serotonin and Go modulate functional states of neurons and muscles involved in C. elegans egg-laying behavior" Curr. Biol. 13: 1910-1915. +supplementary data

Waggoner LE , Hardaker LA, Golik S, Schafer WR. (2000) “Effect of a neuropeptide gene on behavioral states in Caenorhabditis elegans egg-laying”. Genetics 134: 1181-1192

Waggoner LE, Zhou GT, Schafer RW, Schafer WR. (1998) “Control of alternative behavioral states by serotonin in Caenorhabditis elegans” Neuron 21: 203-214.

Zhou GT, Schafer WR, Schafer RW. (1998) “A three-state biological point process model and its parameter estimation” IEEE Trans. Signal Process. 46: 2698-2707.

Kim J, Poole DS, Waggoner LE, Kempf A, Ramirez DS, Treschow PA, Schafer WR (2001) “Genes affecting affecting the activity of nicotinic receptors involved in Caenorhabditis elegans egg-laying behavior” Genetics 157: 1599-1610.

Waggoner LE, Dickinson KA, Poole DS, Tabuse Y, Miwa J, Schafer WR. (2000) “Long-term nicotine adaptation in Caenorhabditis elegans involves PKC-dependent changes in nicotinic receptor abundance” J. Neurosci. 20: 8802-8811.

Schafer WR (2006) "Genetics of egg-laying in worms" Ann Rev Genet. 40: 487-509.

  





       


 






       


           

       










       


           

       










       


           

       










       

               
       



 






       

Links with other motor programs:

Schafer W, Sanchez BM, Kenyon CJ. (1996) "Genes affecting sensitivity to serotonin in Cenorhabditis elegans." Genetics 143: 1219-1230.

Schafer, WR, Kenyon C. (1995) "A calcium channel homologue required for adaptation to dopamine and serotonin in Caenorhabditis elegans." Nature 375: 73-78.

Hardaker, LA, Singer E, Kerr R, Zhou GT, Schafer WR. (2001) "Serotonin modulates locomotory behavior and coordinates egg-laying and movement in Caenorhabditis elegans" J. Neurobiol. 49: 303-313.

Kerr R, Lev-Ram V, Baird G, Vincent P, Tsien RY, Schafer WR. (2000) “Optical imaging of calcium transients in C. elegans neurons and pharyngeal muscle” Neuron 26: 583-594.