Broadened frequency tuning correlates with loss of suppression in auditory nerve fibers

Evidence

There is substantial variability in the relative contribution of suppression to ANF responses (Fig. 5a ), similar to that observed with tone stimuli in the “fractional-response” metric (e.g., Miller et al. 1997 ). There is a group of fibers (both NH and HI) across the CF axis, which show no significant suppression ( ; Fig. 5a ). These are mainly, but not exclusively, of the high-spontaneous-rate class (≥ 18 spikes s‑1 ). HI fibers in the region of greatest damage (~ 2–5 kHz) tend to have reduced suppression. Plotting vs . CF-normalized 10-dB bandwidth, we find a significant correlation between broadened tuning and loss of suppression (Fig. 5b ). Considering only CFs > 2 kHz in this linear regression increased the variance explained from 9.1 to 18.4 %. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3871

Decomposing h 2 into its excitatory and suppressive sub-kernels, we observe a broad area of suppressive tuning which overlaps with the excitatory tuning in time and frequency (Fig. 4d and f ). There is also an “on-CF” component to the suppression, occurring before the excitation. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3816

There is substantial variability in the relative contribution of suppression to ANF responses (Fig. 5a ), similar to that observed with tone stimuli in the “fractional-response” metric (e.g., Miller et al. 1997 ). There is a group of fibers (both NH and HI) across the CF axis, which show no significant suppression ( ; Fig. 5a ). These are mainly, but not exclusively, of the high-spontaneous-rate class (≥ 18 spikes s‑1 ). HI fibers in the region of greatest damage (~ 2–5 kHz) tend to have reduced suppression. Plotting vs . CF-normalized 10-dB bandwidth, we find a significant correlation between broadened tuning and loss of suppression (Fig. 5b ). Considering only CFs > 2 kHz in this linear regression increased the variance explained from 9.1 to 18.4 %. — Dijk, Pim van, Physiology, Psychoacoustics and…, 3865

Categorization

• QUESTION: Is loss of suppression a cause or a consequence of broadened tuning after noise damage, or do both stem from a shared mechanism?
• XREF: Connects to the reader’s ongoing thread on psychoacoustic tuning and cochlear damage from prior chapters. — connects to: Conductive hearing loss shifts tuning curves upward without degrading frequency resolution. — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 1884; Suppression tuning curves mirror inner-ear neurophysiological frequency selectivity; Inhibitory networks that sharpen spectral peaks can aid listeners with reduced frequency selectivity — Professor Dr.-Ing. Hugo Fastl, Professor Dr.-Ing. Eberhard, Psychoacoustics- Facts and Models, 2013 (+8 more)
• corroborated: 4 independent passages support this claim — Dijk, Pim van, Physiology, Psychoacoustics and…, 3871; Dijk, Pim van, Physiology, Psychoacoustics and…, 3816; Dijk, Pim van, Physiology, Psychoacoustics and…, 3865

Broader Connections

• Hearing loss reduces cochlear suppression and compressive nonlinearity together #corroborates (0.88) — Dijk, Pim van, Physiology, Psychoacoustics and…, 3878
• Wider peripheral tuning from hearing loss suppresses low-frequency fluctuation amplitude #corroborates (0.82)
• Broader cochlear filtering reduces low-frequency noise fluctuations, explaining lost masking release #qualifies (0.78) — Dijk, Pim van, Physiology, Psychoacoustics and…, 2161
• Hearing loss impairs frequency selectivity beyond what stimulus level differences explain. #expands (0.75) — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 558