According to Fuster (1995a), the cognitive functions of the frontal cortex, as with any part of the neocortex, consist of the activation and processing within and between networks of representation, or memory networks. Those networks are widely distributed and highly specific, defined by their synaptic structure and connectivity. Thus, the memory code is a relational code, and all memory is associative. In our opinion, one of the most important concepts proposed by Fuster (1995a) is that memory networks overlap and are diffusely interconnected with one another. Thus, a single neuron or group of neurons anywhere in the cortex can be part of many networks and thus many memories. This is why it is virtually impossible, by any method, to localize a memory.