1. Why does the CAP increase in size and duration with increasing stimulus strength?
The CAP is the sum of the individual fibre action potentials. As you increase stimulus strength
you recruit more fibres, thus generating more action potentials, making the CAP look like a
larger bell-curve like shape. Since the nerve is composed of many fibres with various diameters,
the fast fibres (larger diameters) appear at the head section of the CAP, and slow fibres (small
diameters) appear at the tail section of the CAP. As stimulus strength increases, you get a wider
CAP with longer duration.
2. What is the significance of measuring the latency to the beginning of the CAP, vs. measuring it to
the peak of the CAP?
Measuring the latency for the beginning of the CAP shows how long it takes for fast fibres to
produce an action potential from the stimulus to the recording electrode. Taking the
measurement of the latency at the peak of the CAP shows the latency for the AVERAGE fibres in
3. What is the significance of the threshold voltage?
The threshold voltage is the voltage needed to produce at least ONE AP from a fi