Most data point to a "division of labor" among the parts of this system, although this is still being debated and is described in detail below.In animal models, researchers have shown monkeys with damage to both the hippocampus and its adjacent cortical regions were more severely impaired in terms of anterograde amnesia than monkeys with damage localized to hippocampal structures. However, conflicting data in another primate study point to the observation that the amount of tissue damaged does not necessarily correlate with the severity of the memory loss. Furthermore, the data do not explain the dichotomy that exists in the MTL memory system between episodic memory and semantic memory (described below).An important finding in amnesic patients with MTL damage is the impairment of memory in all sensory modalities – sound, touch, smell, taste, and sight. This reflects the fact that the MTL is a processor for all of the sensory modalities, and helps store these kind of thoughts into memory. In addition, subjects can often remember how to perform relatively simple tasks immediately (on the order of 10 seconds), but when the task becomes more difficult, even on the same time scale, subjects tend to forget. This demonstrates the difficulty of separating procedural memory tasks from declarative memory; some elements of declarative memory may be used in learning procedural tasks.MTL amnesic patients with localized damage to the hippocampus retain other perceptual abilities, such as the ability to intelligently function in society, to make conversation, to make ones bed, etc.
In fiction
Notable examples include Lucy Whitmore in 50 First Dates, Jonathan Archer in the Star Trek: Enterprise episode "Twilight", Joseph Gordon-Levitt in The Lookout, Kaori Fujimiya in One Week Friends, Chihiro Shindou in Ef: A Fairy Tale of the Two, Christine Lucas in Before I Go to Sleep, Gus in Remember Sunday. Christopher Nolans psychological crime film Memento (2000) contains a distinguished depiction of anterograde amnesia, in that the memory-impaired protagonist Leonard Shelby is trying to identify and kill the man who raped and murdered his wife, and does so through a system of writing crucial details related to the search on his body and on the blank spaces of Polaroid photographs. Mental health experts have described Memento as one of the most accurate depictions of amnesia in film history, an accuracy that was enhanced by the films fragmented, non-linear structure that mimics the protagonists memory problems.Dory, the happy-go-lucky Regal Blue Tang from Finding Nemo (2003) and Finding Dory (2016), suffers from anterograde amnesia. While Dory forgets conversations within minutes of having them, she never quite forgets who she is, or the fact that she has short-term memory loss, and can therefore explain her bizarre behavior to those around her.Ghajini (2008), a Hindi language film of India based on Memento, in which the main protagonist Sanjay Singhania played by Amir Khan has short-term memory loss, this variant of amnesia. In the film he is behind Ghajini, the killer of his fiancée Kalpana.