There are several areas involved in explicit memory. The hippocampus plays a critical role in short-term memory, which is absolutely necessary if long-term memory patterns are to be established. Lesions of the hippocampus do not affect old, established memories. These lesions affect new declarative learning. Ultimately, memory storage is transferred to other areas of the cerebral cortex, and the location of encoding of these memories may be a function of the type of memory. Established memories involve association areas in the frontal lobe and parieto-temporo-occipital association cortex.