The thalamus is often underestimated in most cerebral models, though it is involved in the main behavioral loops and particularly feeds the cortex with most of its information. It is now clear that the thalamus is not only a relay and plays an important role in attentional processes and levels of awareness by establishing oscillatory rhythms with the cortex. We summarize here some important characteristics of the thalamus together with their supposed functional properties and explain how models at different scales allow to explore them.