  We consider the flavor transformation of neutrinos through oscillatory matter
profiles. We show that the neutrino oscillation Hamiltonian in this case
describes a Rabi system with an infinite number of Rabi modes. We further show
that, in a given physics problem, the majority of the Rabi modes have too small
amplitudes to be relevant. We also go beyond the rotating wave approximation
and derive the relative detuning of the Rabi resonance when multiple Rabi modes
with small amplitudes are present. We provide an explicit criterion of whether
an off-resonance Rabi mode can affect the parametric flavor transformation of
the neutrino.
