Art by Alex Hanson
BBC’s TV series Sherlock takes a modern twist on the classic sleuth tale. The title character, an antisocial drug addict with psychotic tendencies played by Benedict Cumberbatch, is undoubtedly one of the most clever protagonist on television today—rivaled only by other Holmes-inspired characters. One of the biggest reasons to watch the show, other than to see Cumberbatch work his magic, is to see how Sherlock will use his above average intelligence to solve any crime. He seems almost hero-esque in his abilities, but in the episode “The Hound of the Baskervilles” Dr. John Watson introduces the concept of a mind palace. Sherlock is able to solve the unsolvable crime not only because he is observant, but also because of his helpful ability to remember almost everything. Watson explains that Sherlock uses a memory technique where you think up an imaginary place and you stick all the information you want to remember in it, that way you won’t forget anything. All you have to do is “find your way back to it.” It can be any sort of place, so naturally supercilious Sherlock uses a mind palace. In theory though, it could be anything from a street, a closet (as another character later jokes) or a filing cabinet.
Looking closer at the function of memory is important. It doesn’t matter if you’re a detective, a student, or someone trying to remember names at a party: It’s a fact that a good memory will only help you in life. But why do we remember certain events over others? Why do people remember things differently? How can we only remember certain details, sometimes not even in the right order? Since the brain is just a hodgepodge of mystery for most scientists, it’s difficult to really answer any of those questions. Still, examining how the memory processes in the brain actually function is quite important, so here’s what we think happens:
Scientists believe that memories are created in a three step process. If someone is introduced to information that they consciously want to remember— a fact, a name, a specific shade of blue— certain brain structures (the hippocampus, specifically) jump to work. The first step is called encoding. If the bit of information is never encoded, it’s never even entered into the long term system. If our memory process is a filing cabinet, the name is never even written down, let alone placed into a manila folder. The second step is aptly called storage, because that’s just what the structures do— they file that name away. The third and final step is retrieval. In order to make it a memory, you need to remember it. This is where we can run into problems. If we lose the folder with the name in it, you’re stuck using pronouns at the party. The folder is still in the file cabinet, it’s just buried under other names and videos of cats. Luckily, every time you do retrieve the folder, the neural pathway is reinforced. It becomes easier to pull up the name. So every time someone else uses the name, that folder is pulled out again and placed near the front of the file cabinet for easier access next time.
Unfortunately, things can happen in the filing system that cause long term impairment to our memory processes. These breakdowns of memory are called neurocognitive disorders, and they can cause impairment in memory deficits, language and perceptual disturbances, inability to plan and organize, and a failure to recognize or identify objects. Significant head trauma can cause this, along with a number of illnesses, but the most common neurocognitive disorder is Alzheimer’s disease — accounting for two-thirds of all cases. This disease begins with memory loss and disorientation, but quickly progresses to violent behavioral symptoms and hallucinations.
Alzheimer’s was first discovered in 1906 by Alois Alzheimer after he observed severe memory loss and disorientation in a 51 year old patient. An autopsy after her death revealed significant brain abnormalities, including neurofibrillary tangles and deposits of plaques. The plaques, specifically, are deposits of a class of protein called beta-amyloid. This beta-amyloid collects between the spaces of the cells in important brain structures that are critical to the memory processes — the cerebral cortex, amygdala and hippocampus. This buildup of plaque prevents the cells from communicating with each other, which results in extensive cell death and and a shrinking of the brain structures. The file cabinets are disorganized, replaced with a smaller model, and filled with play-dough.
Sherlock is able to use all of his memory processes to his highest benefit, but sciences have a lot yet to learn what really happens when the brain forms a memory. Until we begin to truly understand the memory process, we won’t be able to prevent, or even treat, most neurocognitive diseases. Amnesia, dementia and delirium are disorders that are caused by problems in our filing cabinets, we just have to find a new way to organize our folders.