Cochlear nonlinearities establish F0-synchronized firing patterns that the midbrain converts into rate codes

Evidence

Due to nonlinearities in the healthy ear, phase-locking in each frequency channel is dominated either by a single harmonic, for channels tuned near formants, or by F0, for channels between formants. The alternating dominance of these factors sets up a robust pattern of F0-synchronized rate across best frequency (BF). This profile of a temporally coded measure is transformed into a mean rate profile in the midbrain (inferior colliculus, IC), where neurons are sensitive to low-frequency fluctuations. — Dijk, Pim van, Physiology, Psychoacoustics and…, 5469

Categorization

• DEFINE: Defines the mechanism by which temporal phase-locking information becomes a spatial/rate code across neurons — the key transformation in midbrain speech coding.
• XREF: Connects to Plack’s discussion of phase-locking degradation and to place vs. temporal theories of pitch; also to the general principle of temporal-to-rate conversion seen in other sensory systems.