One powerful means of controlling excitability is to directly modulate the site of spike initiation, the axon initial segment (AIS).
Arbor configurations differed in number of spike initiation zones (3 5) and initial end-organ sizes (13 20).
Mechanisms for spike initiation by subthreshold fluctuations are probably of crucial importance in such a theory.
The bifurcation structure, starting with spike initiation, is SNIC-HB-SN.
Here, (tau_{m}=5mbox{ ms}) is the membrane time constant, (varDelta_{T}= 3mbox{ mV}) gives the slope of the spike initiation, and (V_{S}= -53mbox{ mV}) is the "soft" threshold for spike initiation.
An input of size γ c is sufficient to push the voltage across the threshold for single spike initiation.
Spike initiation in a quiescent neuron is often associated with a threshold phenomenon, which happens when a critical transmembrane potential is exceeded.
Further, the feasibility of the adopted method is interpreted from the point of view of the biophysical basis of spike initiation.
These properties are adaptations that allow these channels to produce currents that can specifically enable fast repolarization of action potentials without compromising spike initiation or height.
Highest LOD scores were obtained for the dates of spike initiation and flowering on chromosome 2H, and for plant height and spike length on chromosome 3H.
For these experiments, 9 connections were chosen with suprathreshold EPSPs and rapid spike initiation.
