Memory

To use the information that has been encoded into memory, it first has to be retrieved. There are many factors that can influence this process, including the type of information being used and the retrieval cues that are present.

Of course, this process is not always perfect. Have you ever felt like you had the answer to a question just out of your reach, for instance? This is an example of a perplexing memory retrieval issue known as lethologica or the tip-of-the-tongue phenomenon. Organizing Memory

The ability to access and retrieve information from long-term memory allows us to actually use these memories to make decisions, interact with others, and solve problems. But in order to be retrievable, memories have to be organized in some way. One way of thinking about memory organization is the semantic network model. This model suggests that certain triggers activate associated memories.3 Seeing or remembering a specific place might activate memories that have occurred in that location.

Thinking about a particular campus building, for example, might trigger memories of attending classes, studying, and socializing with peers. Certain stimuli can also sometimes act as powerful triggers that draw memories into conscious awareness. Scent is one example. Smelling a particular smell, such as a perfume or fresh-baked cookies, can bring forth a rush of vivid memories connected to people and events from a person’s past. 

In order to identify a scent, a person must remember when they have smelled it before, then connect it to visual information that occurred at the same time. So, when areas of the brain connected to memory are damaged, the ability to identify smells is actually impaired.

At the same time, researchers have found that scent can help trigger autobiographical memories in people who have Alzheimer’s disease.5 This underscores just how powerful memories can be. 

Sensory Memory: Sensory memory is the earliest stage of memory. During this stage, sensory information from the environment is stored for a very brief period of time, generally for no longer than a half-second for visual information and three or four seconds for auditory information.

People only pay attention to certain aspects of this sensory memory. Attending to sensory memory allows some of this information to pass into the next stage: short-term memory.

Sensory Memory Types and Experiments

Short-Term Memory: Short-term memory, also known as active memory, is the information we are currently aware of or thinking about. In Freudian psychology, this memory would be referred to as the conscious mind. Paying attention to sensory memories generates information in short-term memory.

While many of our short-term memories are quickly forgotten, attending to this information allows it to continue to the next stage: long-term memory. Most of the information stored in active memory will be kept for approximately 20 to 30 seconds.7

This capacity can be stretched somewhat by using memory strategies such as chunking, which involves grouping related information into smaller chunks. Everyone forgets things at times. Perhaps you misplace your car keys or forget the name of a person you just met. Some degree of memory problems, as well as a modest decline in other thinking skills, is a fairly common part of aging. There’s a difference, however, between normal changes in memory and memory loss associated with Alzheimer’s disease and related disorders. And some memory problems are the result of treatable conditions. If you’re having memory problems, talk to your healthcare provider to get a diagnosis and appropriate care.

Memory loss and aging: Normal age-related memory loss doesn’t cause a significant disruption in your daily life. For example, you might occasionally forget a person’s name but recall it later in the day. You might misplace your glasses sometimes. Or maybe you need to make lists more often than in the past to remember appointments or tasks. These changes in memory are generally manageable and don’t affect your ability to work, live independently or maintain a social life.Memory loss and dementia

The word “dementia” is an umbrella term used to describe a set of symptoms, including impairment in memory, reasoning, judgment, language and other thinking skills. Dementia usually begins gradually, worsens over time, and impairs a person’s abilities in work, social interactions, and relationships. Often, memory loss that disrupts your life is one of the first or more-recognizable signs of dementia. Other early signs might include:

• Asking the same questions repeatedly

• Forgetting common words when speaking

• Mixing words up — saying “bed” instead of “table,” for example

• Taking longer to complete familiar tasks, such as following a recipe

• Misplacing items in inappropriate places, such as putting a wallet in a kitchen drawer

• Getting lost while walking or driving in a familiar area

• Having changes in mood or behavior for no apparent reason

  Diseases that cause progressive damage to the brain and consequently result in dementia include:

• Alzheimer’s disease, the most common cause of dementia

• Vascular dementia

• Frontotemporal dementia

• Lewy body dementia

• limbic-predominant age-related TDP-43 encephalopathy (LATE)

• A combination of several of these types of dementia (mixed dementia)

The disease process (pathology) of each of these conditions is different. Memory loss isn’t always the first sign, and the type of memory problem varies.

Mild cognitive impairment: This involves a notable decline in at least one area of thinking skills, such as memory, that’s greater than the changes of aging and less than those of dementia. Having mild cognitive impairment doesn’t prevent you from performing everyday tasks and being socially engaged. Researchers and physicians are still learning about mild cognitive impairment. For many people, the condition eventually progresses to dementia due to Alzheimer’s disease or another disorder causing dementia. For people with normal age-related memory loss, symptoms usually don’t progress much, and they don’t develop the spectrum of symptoms associated with dementia.

Reversible causes of memory loss Many medical problems can cause memory loss or other dementia-like symptoms. Most of these conditions can be treated. Your doctor can screen you for conditions that cause reversible memory impairment.

Possible causes of reversible memory loss include:

• Medications: Certain medications or a combination of medications can cause forgetfulness or confusion.

• Minor head trauma or injury: A head injury from a fall or accident — even if you don’t lose consciousness — can cause memory problems.

• Emotional disorders: Stress, anxiety or depression can cause forgetfulness, confusion, difficulty concentrating and other problems that disrupt daily activities.

• Alcoholism: Chronic alcoholism can seriously impair mental abilities. Alcohol can also cause memory loss by interacting with medications.

• Vitamin B-12 deficiency: Vitamin B-12 helps maintain healthy nerve cells and red blood cells. A vitamin B-12 deficiency — common in older adults — can cause memory problems.

• Hypothyroidism: An underactive thyroid gland (hypothyroidism) can result in forgetfulness and other thinking problems.

• Brain diseases: A tumor or infection in the brain can cause memory problems or other dementia-like symptoms.

• Sleep Apnea: Untreated sleep apnea can cause memory problems that improve with appropriate treatment.