Neural delay matching proceeds by coarse developmental matching followed by precise activity-dependent refinement

Evidence

Delays from each side must be matched for coincidence detection to occur. How? 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…, 2867

Categorization

• DEFINE: Explains what ‘matching modulo 2π’ and the two-step delay-matching hypothesis actually mean.
• QUESTION: The ‘as yet unknown activity dependent processes’ controlling the ±20 μs refinement remain unspecified - worth chasing.
• XREF: connects to: The brain creates search images by repeated pattern-and-feedback training — Robin Wall Kimmerer, Gathering Moss: A Natural and Cultural…, 71