The single most important advantage that humans have over animals is our abilities to recall memories. How else would we be able to communicate or even think of such simple invention such as a wheel? It is our recollection of the time when we struggled to accomplish simple tasks that drives us to come up with new inventions to better our lives. But who said it would always be peachy? Memory loss is regarded as losing several years of your life. The thought of losing 30-40 or more years of your life is terrifying, and this is why Hollywood loves to make movies from memory loss.
One of the longest movies I have ever seen (in my honest opinion) was the Notebook. This movie circles around the life of one couple, Ally and Noah. What happens is that Ally loses her memory (Alzheimer's) so Noah reads her a diary of their lives and in the end her memory returns for brief moment. As we all know it is near impossible that she has actually remembered their memories. Biochemically, Alzheimer's is caused by abnormal gathering of proteins known as amyloid-beta in the brain causing cell death (Hashimoto et al., 2003). Even if the neural cells had regenerated, it would not have the memory information that the previous cell contained, hence the memories are lost forever. The most logical explanation of the events that take place in the movie is that as Noah reads Ally the stories of their lives with all the subliminal hints that it is indeed the story of Ally's life he is reading, Ally starts believing that it is her past.
The similar situation is seen from the story of Paul Ingram. In that story Paul believes that he had sexually molested his daughters due to several environmental factors such as his daughters, religion, and authorities. In addition, he begins to disregard all the evidences that lead him to believe otherwise. Similarly, Noah's persistence in engraving the stories in Ally's head leads her to believe those things did happen, not that Ally had actually recalled the memories of her past.
Hashimoto, Makoto, Edward Rockenstein, Leslie Crews, and Eliezer Masliah. "Role of Protein Aggregation in Mitochondrial Dysfunction and Neurodegeneration in Alzheimer's and Parkinson's Diseases." NeuroMolecular Medicine 4.1-2 (2003): 21-36. Print.