Dynamic clamp half-center oscillator construction as an assay of variability in intrinsic properties

Rachel Grashow
 
I use the dynamic clamp to construct two-cell reciprocally inhibitory circuits out of gastric mill (GM) neurons from the crab Cancer borealis. Using the dynamic clamp I control both the synaptic connectivity strength (g_syn) between the two neurons, as well as the amount of hyperpolarization-activated inward conductance (g_h) in each cell. I have systematically varied the g_h and g_syn for each biological circuit and searched the parameter space for half-center oscillator behavior. I have found that within the parameter space there exist regimes where cells are silent, bursting, tonically spiking or show an irregular network behavior. In parameter regimes where the cells form half-center oscillators, our findings confirm those of Sharp et al. (1996) in terms of the effects of individually varying g_h or g_syn on the burst frequency of the network. Finally, I have found that disparate amounts of g_h and g_syn can produce similar network output within one experiment. Across experiments the half-center activity regimes within the parameter vary. My hope is to use this method as a functional assay of the variability of the intrinsic properties of neurons across animals.