This book addresses the current debate on the areal specialization of the cerebral cortex, with a detailed examination of the interactions between the developing thalamus and cerebral cortex. It discusses recent in vivo and in vitro approaches and how they reveal possible guiding mechanisms involved in the deployment of the thalamocortical fibers and the earliest interactions between the new thalamic fibers and the developing cortical circuitry. It also presents new views on the possible evolutionary origin of the developmental algorithms employed during thalamocortical development.