Healthy band-enhanced midbrain cells encode formants as rate valleys via synchrony capture

Evidence

Figure 4 shows model responses to the vowel/æ/for the three MTF types for healthy and impaired model AN inputs. The healthy band-enhanced responses (Fig. 4a , blue) reflect the patterns of F0-synchronized rate shown in Fig. 2 ; responses are decreased near formant frequencies (orange arrows), because synchrony capture in the healthy AN reduces the low-frequency fluctuations that ultimately drive this IC type. Band-enhanced neurons tuned to frequencies between formants (Fig. 4a , green arrow) have strong responses due to the strong F0-synchronized rate in the healthy AN for these frequency channels (Fig. 2d , green arrow). The strong contrast in rate across frequency channels for the band-enhanced responses is robust across SPLs and in background noise (Carney et al. 2015 ). — Dijk, Pim van, Physiology, Psychoacoustics and…, 5488

Categorization

Category: Causal Relationships

Related

• Midbrain band-enhanced neurons encode vowels via robust across-frequency contrast (similarity 0.92)
• Healthy band-enhanced IC neurons respond between formants not at them (similarity 0.89)
• Downstream neurons recode F0 phase-locking information into a rate contrast across frequency channels (similarity 0.87)
• Midbrain vowel profiles arise from synchrony-to-rate transformation, not AN rate (similarity 0.85)
• Midbrain formant coding arises from a synchrony-to-rate transformation (similarity 0.84)
• Sensorineural hearing loss changes midbrain coding from contrast-based to energy-based (similarity 0.82)
• Formant frequency coding relies on F0 fluctuation contrast across fibers (similarity 0.82)
• Hybrid midbrain neurons respond to contrasts across fluctuation-rate bands (similarity 0.81)
• Formant frequencies are encoded by F0 fluctuation amplitude across auditory nerve fibres. (similarity 0.80)
• Vowel coding relies on F0-synchronized rate contrasts, not just formant peaks. (similarity 0.80)
• Synchrony capture near formants suppresses F0 phase locking while fibers between formants encode F0 (similarity 0.80)
• Hearing loss erases the neural fluctuation profile that encodes vowel formants (similarity 0.80)
• SNHL disrupts the fluctuation pattern that normally codes vowel formants. (similarity 0.80)
• SNHL reduces synchrony capture so nerve fibers encode multiple harmonics (similarity 0.80)
• The band-enhanced neuron’s timing constrains the band-suppressed neuron’s tuning (similarity 0.80)

Broader Connections

• Neurons can convert stimulus frequency directly into firing rate at the brainstem #corroborates (0.75) — Dijk, Pim van, Physiology, Psychoacoustics and…, 4494
• Groups of nerves firing in staggered cycles code frequencies above 300 Hz #corroborates (0.70) — David M. Howard, Jamie Angus, Acoustics and Psychoacoustics, 900