The cognitive functions of frontal cortex, the latest aquisition of phylogenetic and ontogenetic development, are one of the greatest challenge for cognitive neuroscience of this century and  the next one.    The understanding   of its functions will help us to solve one important problem: how the brain parses the environmental and symbolic world in order to optimally represent the information. This review proposes a theoretical framework for understanding the core cognitive functions of the prefrontal cortex. A great emphasis is put     on the involvement of this cortical area in the creation and maintenance of relational representations  that guide our actions.   Based on   a  formal , description of relational representations and converging evidence from neuroimagistic methods,   two primary functions  of frontal   cortex  are discussed: maintaining representations of elements in working memory in order to process delayed temporal relations and providing resistance to interference using inhibitory mechanisms. Implications for a new kind of neuropsychological assessment based on tasks which can be checked by alternative neuroimagistic methods are discussed.