The GnRH pulse generator is the shared FHN relaxation oscillator (T1)

The hypothalamic GnRH pulse generator is the shared FitzHugh-Nagumo relaxation oscillator: a fast switch with slow recovery emits a relaxation pulse train (62 pulses at τ_s=60). Pulse frequency decodes to gonadotropin identity — fast pulses favour LH, slow favour FSH — reproduced as a monotone function of the recovery timescale τ_s. The mechanism is sim-verified; the absolute pulse rate is a measured anchor.

Run as the vendored FHN at τ_s=60 the generator emits 62 pulses with mean interval 130.6 (arb). Sweeping τ_s from 20 to 400 drops the pulse rate monotonically from 0.019375 to 0.001375, so frequency maps onto the LH/FSH balance — the substrate basis of GnRH frequency coding.

The generator is a relaxation pulse train, not a sinusoid

The arcuate KNDy network that paces GnRH release is, on this substrate, the same fast-slow FHN system used everywhere in the package. A fast R19 switch with slow recovery fires a sharp pulse, recovers, and fires again — a relaxation pulse train rather than a smooth wave.

At the follicular setting (τ_s=60) the generator emits 62 pulses over the run with mean inter-pulse interval 130.6 (arb). Each GnRH pulse drives one downstream gonadotrope pulse (LH/FSH).

Pulse frequency decodes to LH versus FSH

The clinically central fact — that pulse frequency, not amplitude, sets the LH:FSH balance — falls out of the recovery timescale. A faster generator (smaller τ_s) fires more often and favours LH; a slower generator favours FSH, and the pulse rate is monotone in τ_s.

The pulse RATE is calibrated to the measured follicular figure of roughly one GnRH/LH pulse per 60–90 min [L]; the package does not claim to derive that clinical number. Only the monotone frequency-decoding mechanism is the sim-verified [V] claim.