Neural degeneration shifts eCAP firing-component scaling and latency in measurable ways.

Evidence

The ratio of the scaling factors of the late and early component increased with neural degeneration in the guinea pig. This ratio decreased with stimulation intensity in humans. The latency of the early component decreased with neural degeneration in the guinea pig. Indirectly, this was observed in humans as well, assuming that the cochlear base exhibits more neural degeneration than the apex. Differences between guinea pigs and humans were observed, among other parameters, in the width of the early component: very robust in guinea pig, and dependent on stimulation intensity and cochlear region in humans. We conclude that the deconvolution of the eCAP is a valuable addition to existing analyses, in particular as it reveals two separate firing components in the auditory nerve. — Dijk, Pim van, Physiology, Psychoacoustics and…, 2380

Categorization

• QUESTION: The inferential step assuming the cochlear base degenerates more than the apex in humans is worth scrutinizing — how strong is the evidence for that assumption?
• XREF: Connects to the broader cochlear-implant and auditory-nerve physiology work in this volume, and to the mechanism linking neural health to eCAP shape.