Boolean networks are discrete dynamical systems extensively used to model biological regulatory networks. The dynamical analysis of these networks suffers from the combinatorial explosion of the state space, which grows exponentially with the number n of components. To face this problem, a classical approach consists in deducing from the interaction graph of the network, which only contains n vertices, some information on the dynamics of the network. In this paper, we present results in this topic, mainly by focusing on the influence of positive and negative feedbacks.