Why Memory Is Still One of Science's Greatest Mysteries — Part 1

Transcription services like that offered by Simon Says are necessary because the human memory is not always reliable. The process of storing and retrieving memories is beautiful and complex and involves billions of neurons and trillions of synapses operating in a synchronized dance. Many aspects are still shrouded in mystery and will be for years to come.

Over the course of four in-depth blog posts, we’ll attempt to uncover some of memory’s mystique by exploring how memories are formed, the external factors that affect their permanence, the problems we face in retrieving them, and finally, if and how we can improve our memory. But first, we’ll start with the current state of memory studies and where the research is headed.

Theodore Berger, a University of Southern California-Los Angeles neuroscientist, has spent the last 20 years creating a chip implant that mimics the neuronal networks we use to form long-term memories. People who’ve suffered from strokes, head injuries, and Alzheimer’s experience the type of brain damage that prevents these memories from forming. If these chips are implanted in patients who are already suffering from Alzheimer’s, they could potentially reverse the disease’s effects — a remarkable breakthrough concerning this presumed-incurable disease that has baffled the science and medical worlds for decades.

Also, just months after the announcement of Berger’s invention, an MIT research team discovered that LED lights could prevent the kind of blockade formations that cause Alzheimer’s patients to lose memories. And a research team at University of California-San Francisco revealed that the protein hormone klotho, which only a minority of the population possesses, can slow brain aging and boost memory capability.

These discoveries have the potential to change the lives of the 5.5 million people who suffer from Alzheimer’s in America. But why now? When technological creations have reached unprecedented levels, why are we still baffled by our own memories?

How a memory is formed and stored

Your memory plays an essential role in your daily life.

Your memory plays an essential role in your daily life. Whether you’re attempting to remember a complex Excel formula or figure out where you’ve left your car keys, your memory is at work. You know it hasn’t failed you once you’ve successfully finished entering the spreadsheet’s complex formulas. On the surface, pulling up memories may seem simple but the process for forming and storing them is complex because of all the activity in your brain.

Your brain is home to 86 billion neurons, which send impulses throughout your nervous system. If your brain was a computer, it could store approximately 1 million gigabytes of data. Thus, there’s a great deal of information to sort through whenever a memory is formed, stored, or accessed.

The types of memory

There are two main types of memory: short-term and long-term. Short-term memory is like a holding cell. Some scientists refer to it as your brain’s RAM. Some memories stay there just long enough to be used and then you discard them. Others are transferred to long-term memory, which is the brain’s primary system for managing stored information.

However, memory classifications go deeper. There are three types of long-term memory that are stored in your brain. Explicit memory is the kind that requires your conscious thought to pull it up. When you want to recall a powerful scene from a film you saw last year, this is explicit memory. Essentially, it’s what most people speak of when they mention memories. Implicit memory is rote — information you can pull up with little to no mental work. Autobiographical memory is a type of explicit memory that refers exclusively to knowledge of self. These are the objects, experiences, and episodes that help you understand who you are, and that also define certain periods of your life. Whereas explicit memory generally refers to any memory you must work to retrieve, autobiographical memory is always about the details of who you are.

Storing memories

Short-term memories typically last for a window of 15–30 seconds. At the 30-second mark, those memories either dissipate or move on to their permanent home.

Short-term memories typically last for a window of 15–30 seconds. At the 30-second mark, those memories either dissipate or move on to their permanent home. The process of moving to a permanent home is known as encoding. During encoding, information is sent to the hippocampus. The hippocampus is one of the only places in your brain that generates new neurons on a regular basis. Once information reaches this part of your brain, a synapse, or union of two nerve cells, is formed.

These fresh synapses hang out in the hippocampus until they’re pushed out by overcrowding. At this point, your memories start to move throughout the brain in search of their final home. Where those memories land depends on what else is already stored in your brain. Visual memories head to the visual cortex, audio memories stick to your language centers, and so on and so forth. Your new memories cling to existing memories that cover the same information.

Some of this information is repetitive, which strengthens and updates those existing memories. Essentially, your brain is like the World Wide Web, with information dispersed in several places but only vaguely organized. The hippocampus is like your router, directing the flow of information to the right place.

Recalling memories

There isn’t a lot of mystery among scientists surrounding our memory storing process. The only part of the process that isn’t explicitly understood is how the hippocampus handles the flow of information. Research suggests that it prioritizes information, keeping incomprehensible or routine memories in a holding center and then booting them out. But for the most part, we get how our brains store information. Where the mysteries begin is with retrieval of those memories.

When you want to retrieve a memory, your brain sends a signal to that memory from your frontal cortex. The means by which this signal travels are not known in their entirety. Once the signal arrives at the memory, the information is reassembled based on what’s available. Memories that are accessed often are easier to retrieve and vice versa.

Aside from how the frontal cortex signal travels to the requested memory, there are other questions. Is there such a thing as too many memories? Does retrieval fail because there simply isn’t enough space? Are you able to better recall a memory if you repeat an action in the memory? For example, will you only remember something that happened to you during a thunderstorm if there’s a thunderstorm happening? If your memories are updated with newer versions, are your old memories distorted?

It’s questions like these that are driving researchers and leading to new discoveries in the field. If we can understand memory retrieval as clearly as we understand storage, we may be able to combat not only Alzheimer’s but the mental effects of aging and so many other memory-related issues.

Up next, we’ll dive into the role of emotions and external factors in determining which memories stick with us permanently and which ones stay relegated to the short-term.

Read Part 2.