A plot of stimulus voltage (independent variable) vs. AP amplitude (dependent variable) constitutes a stimulus-response relation: The locus of points lies on an asymmetric sigmoid (S-shaped) curve that can be modeled by Gompertz kinetics.
Next topic Previous topic Table of Contents
The size of the spike recorded from a nerve bundle depends on how many fibers are activated. A weak stimulus pulse may excite only a few fibers, producing only a small signal.
As the stimulus (set at 0.1 msec duration) is increased in intensity (voltage), the action potential increases in amplitude but remains essentially unchanged in form. Each increment of stimulus excites a few more nerve fibers, and the currents of those fibers contribute to the total record.
The artifact amplitude increases in equal increments corresponding to the stimulus voltage steps, but the AP amplitude grows by unequal steps.
Figure 20. Stimulus-response relation. The data are fit by a Gompertz equation (Easton 1995, 1997, 1999).
A plot of stimulus voltage (independent variable) vs. AP amplitude (dependent variable) constitutes a stimulus-response relation: The locus of points lies on an asymmetric sigmoid (S-shaped) curve that can be modeled by Gompertz kinetics.
Next topic Previous topic Table of Contents