What is true about the initial waveform recorded of a near-field potential?

The initial waveform recorded of a near-field potential is characterized as positive due to electrotonic depolarization of the membrane under the recording electrode. This occurs when an action potential or synaptic event induces a local change in the membrane potential that spreads to nearby tissues. The electrotonic potential reflects the local depolarization, which is seen as a positive deflection in the recorded waveform at the electrode site.

In the context of neurophysiological monitoring, this type of potential is influenced by the proximity of the electrode to the site of activity; thus, it can capture rapid changes in membrane potential closely and effectively, leading to the positive initial waveform.

The other options are misleading. While stimulus artifact can sometimes overlap with the recorded signals, it does not universally obscure the initial waveform. Not all near-field potentials are negative, as they can indeed present as positive due to the mechanisms mentioned. Additionally, the amplitude of near-field potentials is typically not low due to distance; rather, they are strong and robust when recorded close to the neuron of interest.