Everything Memory

When people tell us why they are taking Brain Fitness Online, they say it is because they want to improve their memory. This lesson is all about Memory, and is actually a summary of a 24-lesson class on memory. It will help you understand what the memory is, how memories are formed and stored, what happens when we experience memory loss, and how we can build and improve our memory, at any age. Though it can be a complex topic, you will come away with a better understanding of your memory, how it works, and what you need to do to improve it. Something we all want to do!

Understanding Memory

Memory may be the most important skill we have. It encompasses not just the ability to recall and enjoy past experiences; it is the ability to acquire and use information to do everything throughout our lives, like speaking our native language, walking, and even holding up our heads (Posit Science, n.d.).

Most adults can quickly and effortlessly recall as many as 100,000 words, but how the brain is able to do this has long been a mystery to scientists (San Diego State University, 2017). What is known is that the human memory is very complex. It is not a single, linear process in the brain, but a group of cognitive processes that interrelate to remind us of experiences, facts, and procedures. The human memory is truly a remarkable thing! It empowers our intelligence, enables us to function, and makes our relationships with each other rich and meaningful.

Memory Systems

There are two types of memory systems: the short-term memory system and the long-term memory system.

Short-Term Memory

Short-term memory is the memory type that processes what is happening in the here and now. It acts as a kind of mental “scratch-pad” for temporary recall of information that is being processed at any point in time. It has been referred to as the brain's “Post-it note.” The short-term memory holds a small amount of information (typically around seven items or less) in mind in an active, readily available state for a short period of time (typically from 10 to 15 seconds, or sometimes up to a minute or two) (Merzenich, 2013). An example of this is happening right now. In order for you to understand this sentence, your short-term memory needs to hold the beginning of the sentence in mind while the rest of the sentence is read, so that you can make sense of it. The same thing happens when you are listening to someone speak. Imagine if you couldn’t remember the beginning of their sentence by the time they got to the end!

Although we cannot expand our short-term memory, with practice, we can improve our ability to hold the information it is able to remember, so we can better use it. It can also be improved by chunking information (breaking up long strings of information into units or chunks), or using specific coding tricks. To test your own short-term memory, try this fun activity.

Short-term memory can be thought of as the gateway to long-term memory. It is facilitated by two other types of memory--Sensory Memory and Working Memory.

Sensory Memory

Memories begin with the sensory input. What begins as a slight sensory glimpse, a vision, a sound, or a taste can become the most poignant memory. When this sensory input occurs, you can ignore it or you can pay attention to it and allow yourself to perceive it. Only if you pay attention and perceive that sensory input, will you begin to remember it. If you pay no attention to the sense, then it disappears.

Sensory memory is very short, most times a fraction of a second to a few quick seconds. Its purpose is to hold that sensory input for a very short time to make sure that you don’t need it. You are talking to a friend. Suddenly, they ask you something and you say, “What?” Before they can ask you again, you have suddenly remembered what they said and you can reply to it. This is your sensory memory.

Sensory memory is the gateway to short-term memory. When you pay attention to and perceive the sensory input, it moves to short-term memory.

Working Memory

The term working memory is often used interchangeably with short-term memory, although technically, working memory refers more to the whole theoretical framework of structures and processes used for the temporary storage and manipulation of information, of which short-term memory is just one component (Mastin, n.d.). Working memory refers to the mental processes that keep memories in mind for a short time. The working memory processes allows you to hold a memory briefly, such as a phone number, until you can write it down.

In this 9-minute Ted Talks video, Peter Doolittle describes working memory as he challenges us with our own working memory, and show us how it helps us to make sense of the world. Key point: What we process, we learn!

In this second Ted Talks video, Torkel Klingbert offers some ways to improve your working memory capacity, based on the neuroscience of working memory. You will be interested to see that his idea of working the memory is very similar to what you do with BrainHQ.

Long-Term Memory

Long-term memory is the memory type intended for storage of information over a long period of time. Long-term memory actually decays very little over time and can store a seemingly unlimited amount of information almost indefinitely (Merzenich, 2013). There is some debate as to whether we actually ever “forget” anything at all, or whether it just becomes increasingly difficult to access or retrieve certain items from long-term memory.

There are two categories of long-term memory: explicit and implicit. Under these categories are further sub-categories of memory systems. Let's take a look at each one.

Implicit Memory (Unconscious)

Implicit memory, also known as non-declarative memory, is the system that allows humans to learn structures of everyday life, such as grammar, music, etiquette, and more. When we encode these structures, we make predictions about future events (allowing us to act and respond in certain ways); it also helps us to notice events that do not fit into the patterns. Implicit memory is encoded by repeated experience with some context without attempting to learn anything. An example is musical genre. Even if you have never heard a song, you can identify if it is blues, rock, or country.

Implicit memory is sometimes referred to as unconscious or automatic memory. It uses past experiences to remember things, no matter how long ago those experiences occurred. Implicit memory allows us to remember things without actually thinking about them. An example would be buttoning a shirt. Implicit memory does not provide a clear answer, only a look at structure which guides behavior.

There is no particular context associated with implicit knowledge. It works with explicit memory to further understand a memory or concept. An example is a medical student who begins to see patients after completing the academic part of their studies. The patients will help the intern to develop an understanding of symptoms and illnesses to add to the intern's semantic memory of these same things.

There are a few subsets of implicit memory—procedural memory and priming (Zimmerman, 2014a):

Procedural memory is involved in learning new motor skills or an automatic routine, such as a dance. It enables us to perform everyday physical activities like walking or riding a bicycle without having to think about it (Zimmerman, 2014a). Procedural memory is enhanced through practice and repetition, and is sometimes referred to as muscle memory. When you begin to learn a movement, you rely on your short-term and working memory, but as you become more adept, the movement becomes smooth, and the memory is transferred into procedural memory, where it can become habitual and subconscious.
Priming is another, smaller subset of implicit memory. It is a type of implicit memory where exposure to one stimulus influences the response to another. Priming involves using pictures, words, or other stimuli to help us recognize a word or phrase. An example is when people are asked to remember groups of words. They will remember them more effectively if they are from the same category. For example, "nurse" will be recognized if it follows "doctor" more effectively than if it follows "bread." Another example is when we use the color green to remember grass, or red to remember apples (Zimmerman, 2014a).

Explicit Memory (Conscious)

Explicit memory, also called declarative memory, involves a conscious attempt to retrieve memories of past events. Using explicit memory requires an effort to bring those memories to the surface. It provides a clear answer to a question. For example, while you might be able to easily name the days of the week (implicit memory), it takes explicit memory to recall that you have an appointment next Tuesday (Zimmerman, 2014a). There are two sub-categories of explicit memory: semantic memory and episodic memory.

Semantic memory involves only the recollection of facts. This type of memory is not associated with emotion or personal experience. An example of semantic memory is recognizing the names of colors (Zimmerman, 2014b). Another example is when you can recall a fact that you have learned long ago and it is not related to any life experiences, such as what the capital of North Dakota is. This memory has no context, as you have heard this information many times and in many places.
Episodic memory is having a unique memory of a specific event, or when you review an episode from your life, like what you had for dinner. An example of episodic memory is remembering where you were when you found out about the September 11, 2001 attacks at the World Trade Center and the Pentagon (Zimmerman, 2014b). This type of memory relies on the context in which it was formed.

How Memory Works

As mentioned earlier, the human memory is complex and not yet fully understood. However, through years of research and experimentation, we have a basic idea of how the brain creates, stores, and retrieves memories.

Sensory Input

Memory begins with sensory input—sight, sound, taste, smell, or touch. These inputs last only a fraction of a second to a few seconds, and will disappear if we pay no attention to them. However, if we pay attention to an input, we begin to remember it. Paying attention starts this process of moving an input into short-term memory. Short-term memory is where sensory inputs are processed. So it can be said that sensory input is the gateway to short-term memory.

By your attention to sensory input, you have begun the process of creating a memory, which the brain now tries to make sense of. Is that smell pleasurable? Did you feel frightened by that visual scene? Were several senses engaged at once? All of these things need to be taken to the brain, where they are encoded and processed. At this point, you need to work closely with these memories if you want to get them into short- term memory. You need to find some way to link several different segments of the memory, in a process called consolidation. Then you need to begin to retrieve the memory. Think about it actively, try to recount the various ways that the memory was significant. You find that the memory becomes stronger if it is combined in a variety of modes, such as visual and speech, or touch and smell.

Short-Term to Long-Term Memory

Sensory information will quickly disappear from the short-term memory unless we make a conscious effort to retain it. Short-term memory is a necessary step toward the next stage of retention--long-term memory. As you would suspect, it requires some work to take that initial sensory input and embed it into your long-term memory. When we actively think of and interact with short-term memory, it is moved to long-term memory. The transfer of information to long-term memory for more permanent storage can be facilitated or improved by mental repetition of the information or, even more effectively, by giving it a meaning and associating it with other previously acquired knowledge. Long-term memory is improved when multiple systems in the brain are used to remember something. The key to keeping something in long-term memory is to practice frequent retrieval of information. Motivation is also a consideration, in that information relating to a subject of strong interest to a person is more likely to be retained in long-term memory. So we can say that short-term memory is the gateway to long-term memory.

There are three phases in the process of helping your working memory create a long-term memory:

1. Getting the information into the short-term memory (pay attention to sensory inputs that you wish to remember--FOCUS!)

2. Handling the information appropriately while it is in the short-term memory. You can do this by:

a. Working with only small amounts of new information at a time.

b. Clearing out unneeded, old information from the working memory.

c. Chunking several pieces of information together.

d. Practicing "retrieval" by calling up the information repeatedly.

e. Remembering dual coding (trying to encode each memory using multiple senses, like vision, speech, touch, etc.)

3. Moving information from short-term to long-term memory, through the processes of the working memory, and then using this information in a constructive manner (discuss it with a friend, take a test, write a paper, etc.).

The process of memory consolidation, done by the working memory, takes place in the hippocampus, where memories are stored, and then transferred into long-term memory. Encoding enables this transfer of information. People tend to remember the beginning of things (also known as the primary effect) and the end of things (also known as the recency effect). The beginning things spend the most time in working memory; the endings are remembered because they may still be in working memory.

Using Multiple Memory Systems

As was just mentioned, long-term memory is improved when multiple memory systems are used to remember something. An excellent example of this is found in a study led by a neurologist at University College London (Maguire et al., 2000). Study participants were taxi cab drivers and bus drivers in London, England. In a comparison of their brains, it was found that the hippocampi of the taxi drivers were significantly larger than those of the bus drivers (the control subjects), after controlling for age, education, and intelligence. The reason was found to be that the taxi cab drivers used three types of long-term memory in their daily work tasks: a) Episodic = memories of street closures, traffic accidents, etc.; b) Semantic = memories of the thousands of streets of London; and c) Procedural = the memory of the act of driving; whereas, the bus drivers simply followed a pre-planned daily route, and didn’t need to use as many memory systems. These findings should motivate us to use as many of our own memory systems as possible when analyzing a problem or performing a task, so we can improve our memories even more.

What Happens in the Brain

The hippocampus, that important part of the brain within the limbic system, is responsible for, among other things, processing sensory inputs and consolidating short-term memories into long-term memories. It works with information by encoding, storing, and retrieving it. The hippocampus area of the brain essentially acts as a kind of temporary transit point for long-term memories, and is not itself used to store information (Mastin, n.d.).

Physiologically, the establishment of long-term memory involves a process of physical changes in the structure of neurons in the brain, although there is still much that is not completely understood about the process. At its simplest, whenever something is learned, circuits neurons in the brain, known as neural networks, are created, altered, or strengthened. These neural circuits are composed of a number of neurons that communicate with one another through special junctions called synapses.

Through a process involving the creation of new proteins within the body of neurons, and the electrochemical transfer of neurotransmitters across synaptic gaps to receptors, the communicative strength of certain circuits of neurons in the brain is reinforced. With repeated use, the efficiency of these synaptic connections increases, facilitating the passage of nerve impulses along particular neural circuits. Forgetting occurs in long-term memory when the formerly strengthened synaptic connections in a neural network become weakened (Mastin, n.d.).

Recent Research on Memory

There have been new developments in the field of memory and how it works in the past few years. Some of these developments challenge the way we have looked at memory. Further studies are needed to understand if these new theories are valid. Let’s look briefly at just a few of these theories.

San Diego State University

A 2017 study by San Diego State University neuroscientist Stephanie Ries looked at the question of how we retrieve words from our memory—specifically, how we narrow down a “smorgasbord of related concepts” to the one word we’re really looking for (San Diego State University, 2017). This process of memory retrieval is complicated and poorly understood. Ries looked at epilepsy patients who had a grid of electrodes directly atop their brains to measure their cortical activity. It was discovered that overlapping swaths of the brain work in parallel to retrieve the correct word from memory. This challenges the thought that memories might be “stored” in one place or area of the brain.

Let’s look at an example of how this might work. When you look at a picture of a mug, for example, the neurons that store your memory of what a mug is begin firing. A host of neurons that code for related ideas and items (bowl, coffee, spoon, plate, breakfast, etc.) are also activated. Neuroscientists have found that the brain organizes ideas and words into semantically related clusters, which it activates when trying to recall a specific word. It is how the brain narrows this down to “mug” that Ries is studying (San Diego State University, 2017).

Massachusetts Institute of Technology (MIT)

Since the 1950s, it has been thought that all memories start as a short-term memory in the hippocampus and are then slowly converted into long-term memory in other parts of the brain. In other words, the hippocampus collects short-term memories while the cortex retains long-term memories. The discovery of multiple areas of memory storage was made when Henry Molaison, a man whose hippocampus was damaged as a result of epilepsy surgery, could no longer make new memories; yet his memories from before the operation remained intact, supporting the theory that two parts of the brain are involved in collecting and storing memories (Donnelly, 2017).

A recent MIT study, published in 2017, could be a game-changer in the understanding of how memories are made and consolidated. In the study (Kitamura et al., 2017, Trafton, 2017) evidence reveals for the first time that memories are actually formed simultaneously in the hippocampus and the prefrontal cortex in a parallel fashion. This is contrary to the standard theory of memory consolidation, which says that you gradually transfer the memories. According to the study, the memory is encoded in the prefrontal cortex at the same time as it is in the hippocampus. They then go different ways—the prefrontal cortex memories, initially immature or silent, begin to mature and become stronger while the memories in the hippocampus become weaker. As the memories age, there’s a shift in the balance of which circuit is engaged when a memory is recalled. In brief, the hippocampus shares the task with the pre-frontal cortex simultaneously. These new findings may force some revision of the dominant models of memory and how memory consolidation occurs.

More on Memory

Memory and Aging

Research has found that memory may not be as fleeting as originally thought. Specifically, procedural and semantic memory show little decline with aging, and may be more related to physical things (arthritis, hearing, vision). Although episodic memory does show some decline, it may not be as much as originally suggested, as memory depends on the time of day. For older adults, the best time of day is the morning, and not late afternoon (when these studies were originally performed). As for the retelling of stories, it was suggested that this may actually be an evolutional process to retain our information from generation to generation. The best ways to improve episodic memory are to use complex activities such as dancing, painting, writing, and lifelong learning.

Learning and Memory

Learning a procedural task requires explicit instruction when there is a single right way to do something (such as performing a scale on the piano). Constructivist learning is when you try to figure it out for yourself. Constructivist learning encourages creativity and shows the multiple ways to interpret behavior. Classical conditioning is a subconscious learning event when a certain stimulus will predict another stimulus. An example is the story of Pavlov’s dogs, which were conditioned to expect food when they heard a bell. They eventually salivated whenever they heard the bell. In this case, the behavior (salivating with a bell) became habit.

Déjà vu

Déjà vu is a French term meaning “already seen”. It is that eerie feeling that you have experienced something before. Causes are not known, but may be related to semantic overlap (linking a familiar experience with the present experience), priming (when your memories prepare you for something you are going to experience), hologram memories (some aspect of the current experience may retrieve a blurry version of a past experience), or indirect experiences (experiences through books and movies that we feel we have personally experienced). Déjà vu suggests that sometimes declarative (explicit) and non-declarative (implicit) memory can become disassociated, and the result is that feeling that you have been here before.

Memory Loss

Many students report that they take the Brain Fitness class because they are having trouble with their memory and they want to prevent further loss, or reverse that loss. Many even express fear of losing their memory in the future, and want to prevent that. People of all ages experience inconvenient—and sometimes embarrassing—memory lapses. Who hasn’t forgotten where they parked their car? But when older people are forgetful, many begin to worry that the slip-ups are signs of Alzheimer’s disease (AD). Alzheimer’s is a real concern, but we needn’t fear that every memory lapse is a sure sign of it. Memory loss happens to all adults, and only in some cases does it signal a serious condition. Let’s look at a few of the common causes of memory loss in maturity.

Normal Age-Related Cognitive Changes

Studies confirm that the ability to remember details about our experiences, to manipulate multiple bits of information at the same time, and to identify the source of what we have learned, often declines as we get older. This process actually begins as early as age 30, though it accelerates and becomes more noticeable after age 50. Although these cognitive changes can be annoying—and ultimately, can limit our activities and interests—they are a part of normal aging. Recent research has indicated that keeping your mind engaged in new and challenging activities can help to prevent or reverse this normal cognitive decline.

Mild Cognitive Impairment (MCI)

Mild cognitive impairment (MCI) is a term that is used to describe a more serious kind of memory decline. Like those aging normally, people with MCI may complain that their memory isn’t what it used to be, and their loved ones might agree. But in addition to these general complaints, they also do worse on certain memory tests compared to others in their age group. Unlike in Alzheimer’s disease and other forms of dementia, though, people with MCI do not show impaired judgment.

Scientists aren’t certain exactly how many people have MCI. Estimates range from 1% to 26% of Americans 65+. For some people, MCI represents a transitional period between the mild and manageable memory problems associated with normal aging, and the debilitating symptoms of AD. Estimates vary, but a number of studies suggest that about 10% of those with a specific type of memory-related MCI go on to develop AD each year (Posit Science, n.d.; Posit Science, n.d.a).

Other Causes of Memory Loss

There are many other possible causes of memory loss. Included among these are:

• Trauma to the head

• Stroke

• Medications

• Alcohol, tobacco, or drug use

• Depression

• Stress

• Sleep deprivation

• Thyroid disease or other infections

Evaluating Memory Loss

Some of the above causes of memory loss can mean that the loss may only be temporary or short-term. With proper evaluation, care, and treatment, memory can be restored in many cases to its former strength and effectiveness. However, if you are experiencing frequent memory lapses, or others are mentioning that they notice a loss in your memory, it is recommended you visit your doctor. Your doctor knows your medical history and can provide a thorough physical exam to rule out any other medical reason for your memory loss. A doctor can also refer you for a neurologic exam where your mental abilities will be tested and evaluated. Further evaluations could include blood and urine tests, nerve tests, or imaging tests (CAT scan, MRI, etc.).

Locally, The Alzheimer’s Project Clinical Roundtable published an extraordinary work in December 2016 called “The Alzheimer’s Project.” It contains physician guidelines for the screening, evaluation, and disease management of Alzheimer’s disease and related dementias. With the permission of the Roundtable, given by Dr. Sherry Braheny, who serves on the Disease Management Subcommittee, we are able to share some of the information from this publication in this course (see Additional Resources: Handouts).

Treatments for Memory Loss

Treatment for memory loss depends on the diagnosed cause(s). If the cause is deemed to be temporary and thus reversible, a single therapy or combination of therapies can be effective to reverse it (e.g. medication, supplements, counseling, exercise, diet). However, if the diagnosis is more serious and is progressive (e.g. dementia, etc.), further steps would likely be taken by medical professionals to treat it, including those previously mentioned.

Improving Our Memory

This semester, we will learn about many of the lifestyle choices we can make to help reverse or slow down memory loss. These lifestyle choices include practicing good nutrition, getting adequate exercise and sleep, engaging in challenging mental activities, having an active social life, and managing the stress in our lives.

Enjoy this 4-minute Ted Ed video called "How Memories Form and How We Lose Them." It’s a great wrap-up of what we have learned about the memory.

Works Cited

Donnelly, L. (April 7, 2017). Scientists discover the ‘beautiful’ secret of how memories are made. The Telegraph. Retrieved from: http://www.telegraph.co.uk/science/2017/04/07/scientists-discover-beautiful-secret-memories-made/

Kitamura, T., Ogawa, S. K., Roy. D. S., Okuyama, T., Morrissey, M. D., . . . Tonegawa, S. (2017). Engrams and circuits crucial for systems consolidation of a memory. Science, Vol. 356, Issue 6333, pp. 73-78. doi: 10.1126/science.aam6808

Maguire E. A., Gadian, D. G., Johnsrude, I. S., Good, C. D., Ashburner, J., . . . Frith, C. D. (2000). Navigation-related structural change in the hippocampi of taxi drivers. Proceedings of the National Academy of Sciences of the United States of America, 97(8). 4398-4403. doi: 10.1073/pnas.070039597. Retrieved from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC18253/

Mastin, L. (n.d.). Short-term (working) memory. The Human Memory. [Website]. Retrieved from: http://www.human-memory.net/types_short.html

Merzenich, M. (2013). Soft-wired: How the new science of brain plasticity can change your life (2nd ed.). San Francisco, CA: Parnassus Publishing, LLC.

Posit Science. (n.d.). All about memory. [Website]. Retrieved from: https://www.brainhq.com/brain-resources/all-about-memory

Posit Science. (n.d.a). Session 15: Memory lapses handout. [Curriculum]. Not available on public website.

San Diego State University (June 19 2017). Mapping how words leap from brain to tongue: Neuroscientist explores the complex brain connections employed during word retrieval.” ScienceDaily. Retrieved from: www.sciencedaily.com/releases/2017/06/170619144827.htm

Trafton, A. (April 6, 2017). Neuroscientists identify brain circuit necessary for memory formation: New findings challenge standard model of memory consolidation. MIT News. Cambridge, MA: Massachusetts Institute of Technology. Retrieved from: http://news.mit.edu/2017/neuroscientists-identify-brain-circuit-necessary-memory-formation-0406

Zimmerman, K. A. (2014a). Implicit memory: Definition and examples. Live Science. [Website]. Retrieved from: https://www.livescience.com/43353-implicit-memory.html

Zimmerman, K. A. (2014b). Semantic memory: Definition and examples. Live Science. [Website]. Retrieved from: https://www.livescience.com/42920-semantic-memory.html

Page updated

Report abuse