Chunk #18 — 3. Impact of spatial scale on CSD implementations — 3.1. Empirical considerations for linear (one-dimensional) intracranial recordings — 3.1.1. The cortical dipole and field closure
a stable morphology. Although the field potential amplitude noticeably increases with increased proximity to primary auditory cortex (at about 22 mm), it is only within the generating tissue (i.e., 23–24 mm) that amplitudes and spatial gradients become quite large, whereupon the morphology of the waveform is transformed, and cleanly inverts below the cortical generator (i.e., 25–26 mm). The comparability and polarity-inverted AEPs above and below the generator (e.g., compare waveforms at 20 mm and 26 mm) provide the informal basis for the notion of a cortical dipole.
