Binaural coincidence precision emerges through Hebbian-tuned coarse then fine delay matching

Evidence

Coincidence requires microsecond precision, which may be achieved by a two-step process, where latencies from each ear are matched during development, and then precisely matched modulo 2π. This was first proposed by Gerstner et al. ( 1996 ), who postulated that the necessary degree of coherence in the signal arrival times could be attained during development by an unsupervised Hebbian learning rule that selects connections with matching delays from a broad distribution of axons with random delays. Our data support this matching hypothesis, with coarse delays laid down through normal development, and precise, i.e. ±20 μs modulo 2π, delays regulated by some as yet unknown activity dependent processes (Seidl et al. 2010 ). — Dijk, Pim van, Physiology, Psychoacoustics and…, 2866

Categorization

• DEEPTHINKING: Developmental mechanism by which an unsupervised Hebbian rule sculpts microsecond temporal precision from individually noisy, coarsely variable elements — a genuinely two-stage solution worth sitting with.
• QUESTION: What exactly are the ‘unknown activity dependent processes’ that refine delays to ±20 μs after coarse developmental matching?