Threshold burst current

As with all initiators, we cannot state an exact firing energy, or in this case burst current, because of the statistical nature of these devices. We must describe the firing requirement in terms of mean and standard deviation. The mean burst current, for a given EBW detonator, is called the threshold burst current, and its symbol is i bth-... 

ACh can sometimes inhibit neurons by increasing K+ conductance and although it has been found to hyperpolarise thalamic neurons, which would normally reduce firing, strong depolarisation may still make the cell fire even more rapidly than normal. This appears to be because the hyperpolarisation counters the inactivation of a low-threshold Ca + current which is then activated by the depolarisation to give a burst of action potentials (McCormick and Prince 1986b). 

Now we have seen that the burst action is constant for a particular wire material and diameter that the shape of the current-time trace is not a factor in achieving burst that the current-time trace is determined by the fire set and cable parameters that as long as we get burst, and as long as that burst current is sufficiently above threshold, we will detonate the initial pressing. To emphasize this. Figure 25.11 shows current traces and burst points that fired detonators from a wide variety of fireset/cable values. 

White G, Lovinger DM, Weight FF 1989 Transient low-threshold Ca current triggers burst firing through an afterdepolarizing potential in an adult mammalian neuron. Proc Natl Acad Sci USA 86 6802-6806... 

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