The medial Reticular Formation (mRF) is located in the brainstem: it receives many sensory inputs and it can control motor actions through its projections on the spinal cord and cranial nerves. The mRF is phylogenetically one of the oldest neural structures of the brainstem, the latter being regarded as one of the oldest centers of the central nervous system. Subsequently it seems to be a low-level system for action selection. The first model of the mRF was proposed by [Kilmer et al., 1969], who already proposed that the mRF could be a” mode selector”.[Humphries et al., 2005] tested the efficiency of this model in the minimal survival task defined in [Girard et al., 2003]. It performed poorly, but another version of it that included artificially evolved weights performed quite honorably. As a result, [Humphries et al., 2006] proposed a second model of the mRF, based on neural network formalism and taking into account new anatomical data. Nevertheless, it showed poor performances in the minimal survival task and turns out not to be anatomically very plausible.