Description:Human intelligence has evolved from ancestral invertebrate neural systems. Present-day invertebrates hold neural circuitries in various degrees of complexity, an understanding of which may help us to decipher the basis of our own systems. This special issue contains six reviews covering various lineages of invertebrates gathered here to offer the specialist and non-specialist inspiring insights into a wide spectrum of invertebrate systems with enormous potentials in the post-genomic era. Scientists involved in the frontiers of neuroscience research will find this publication useful reading as it summarizes lessons from the invertebrate models on primary topics like control of complex behaviour, synaptic plasticity, and network guidance and formation.