Hippocampus Thomas Henry Huxley and Richard Owen, satirised as the Great Hippocampus Question. The term hippocampus minor fell from use in anatomy textbooks, and was officially removed in the Nomina Anatomica of 1895. Today, the structure is just called the hippocampus, with the term "Cornu Ammonis" surviving in the names of the hippocampal subfields CA1-CA4. The term "limbic system" was introduced in 1952 by Paul MacLean to describe the set of structures that line the edge of the cortex (Latin "limbus" meaning "border"): These include the hippocampus, cingulate cortex, olfactory cortex, and amygdala. Paul MacLean later suggested that the limbic structures
Long-term memory be needed to preserve long term memories. Individual retrievals can take place in increasing intervals in accordance with the principle of spaced repetition. This can happen quite naturally through reflection or deliberate recall (also known as recapitulation), often dependent on the perceived importance of the material. Using testing methods as a form of recall can lead to the testing effect, which aids long term memory through information retrieval and feedback. Some theories consider sleep to be an important factor in establishing well-organized long-term memories. "(See also sleep and learning.)" Sleep plays a key function in the consolidation of new memories.