Digital operations can be deceptive. Squid giant axon membrane.

Action potentials produced by current clamp stimuli have been used to voltage-clam axons, an analogue, and computers. The final currents reproduced the original stimulus except during the action potential, when fluctuations of greater than +/- 20% were found. But all of these operations were digitalized. When the original action potential from an analogue was recorded directly on magnetic tape and played back as the voltage clamp, the original stimulus was reproduced within experimental error. Five collaborators and I have shown that the digital transients can accumulate to surprising values.