Since many years, it has been emphasized the interest of the spin-isospin nuclear response in the quasi-elastic peak region, due to the possible onset of collective effects. The latter were found to be quite sizable within an RPA treatment of infinite nuclear matter 1. In this framework (and in the so-called ring approximation) the spin-longitudinal (transverse) response is proportional to the imaginary part of the following particle-hole (ph) polarization propagator $${{R}_{{L(T)}}}(q,\omega )\alpha - \operatorname{Im} \frac{{{{\prod }^{0}}(q,\omega )}}{{1 - {{V}_{{L(T)}}}(q,\omega ){{\prod }^{0}}(q,\omega )}},$$ (1) Π0 being the sum of the nucleon-hole and Δ-hole free propagators.