Memory

What is memory?

Memory is the process of recalling information that you learned. Many parts of your brain work together to collect information and store it so you can find and access it when you need it. There are different ways memory can be classified.

Memory is a vital human process. You use it for problem-solving, like answering a question on a test. It helps you plan and navigate through familiar and unfamiliar places. It involves your language development (remembering someone’s name, for example). Your memory also helps with reasoning, like avoiding things that previously caused you harm.

As you get older, your memory may not work as quickly as it used to. This is a normal part of aging. But sometimes, underlying conditions can affect how well the parts of your brain responsible for memory function. A healthcare provider can help you if you have any questions about your memory.

What are the types of memory?

There are three main types of memory:

• Sensory memory: This is information collected from your senses (hearing, touch, smell, taste and vision). You only store it for a couple of seconds. You don’t consciously control this type of memory but it’s highly detailed.
• Short-term memory: This is a temporary storage space. It holds information for a few seconds to minutes. It’s easily accessible.
• Long-term memory: This is a mostly permanent storage space. You can hold information here for years. There isn’t a limit on how much information you can store.

Sensory memory

Sensory memory types represent each of your senses:

• Echoic memory: Hearing.
• Haptic memory: Touch (somatosensory).
• Gustatory memory: Taste.
• Iconic memory: Vision.
• Olfactory memory: Smell.

Short-term memory

Short-term memory has a limited capacity and duration. You can think of short-term memory as an exclusive VIP club. You can only stay there for a little bit before someone escorts you out.

You can, however, manipulate your short-term memory by increasing the capacity and duration. There are two strategies to do this:

• Chunking: You can organize material (information) into groups to help you remember more (recalling a license plate number as two sections instead of one).
• Rehearsing: You can continuously repeat the information to extend how long you remember it (like by singing a song multiple times to remember the lyrics).

Because you can organize, process and use information from short-term memory, researchers coined the terms “working memory” or “short-term working memory” and use them interchangeably.

Long-term memory

There are two main types of long-term memory:

• Declarative or explicit memory: This is the storage of facts, events and locations. You’re continuously adding and recalling information.
• Non-declarative or implicit memory (procedural memory): This is the storage of learned skills, habits or relationships. You can consciously or unconsciously access these.

How does memory work?

There are four parts to every memory:

1. Gathering: You take in information from your environment.
2. Encoding: Your brain translates the information into an easily stored format.
3. Storage: Your brain organizes and keeps the translated information in your brain.
4. Retrieval: You select and find the stored information you want to remember.

Your brain has a very specific strategy for gathering, encoding, storing and retrieving memories. It involves the coordinated efforts of neurons (nerve cells), neurotransmitters, synapses and many different brain regions.

What part of the brain controls memory?

Memories form in your hippocampus. This is a part of a larger structure (temporal lobes). The temporal lobe sits behind your temples. You have a temporal lobe (and hippocampus) on each side of your head. They help with memory retrieval.

Other parts of your brain participate in memory processes:

• Long-term memory: Basal ganglia, cerebellum, neocortex, striatum and amygdala.
• Short-term memory: Prefrontal cortex.
• Sensory memory: Sensory cortex, parietal lobe and temporal lobe.

What are memory disorders?

Memory disorders are conditions that target and damage the parts of your brain that regulate memory. These conditions may cause symptoms that affect more than just your ability to remember.

Common examples of conditions that may affect different aspects of your memory include:

• Alzheimer’s disease and other types of dementia.
• Brain tumor.
• Depression.
• Intellectual disability.
• Sleep deprivation.
• Stress.
• Stroke.
• Thyroid conditions.
• Traumatic brain injury.

Do genetics affect memory?

Yes, genetics can affect your memory in the following ways:

• Brain structure and function: The way your brain develops and works has a lot to do with the instructions your genes provide. As your brain holds your memories, this may affect your short- and long-term memory.
• Genetic changes: Some conditions that affect how well your memory works happen due to genetic changes (mutations). Some of these pass to your biological family, while others happen randomly.
• Epigenetics: Your lived experiences can influence how your genes and body function. As you’re constantly learning from your experiences, your memories are helping your body better interact with the world around you.

Your memory is made up of life experiences and interactions with your surroundings. Memories themselves don’t pass through your genes.

Why do we forget some memories?

You’re constantly learning new things and having new experiences. While you might think of your brain as a hard drive where you store all sorts of information, your brain selects the most important memories to keep over others instead of storing everything.

There are things outside of your control that can affect your memory, too, like underlying conditions or injuries that damage memory-forming or storing parts of your brain.

A lack of sleep, trauma or stress may make thinking and remembering clearly more challenging. In certain situations, your brain may choose to protect you from harmful memories by blocking them out (selective memory).

Talk to a healthcare provider if you’re forgetting more than you’re able to remember.