The role of episodic and semantic memory in remembering and imagining

Question 1

What are episodic and semantic memories?

Answer 1

• Explicit memories, also called declarative memories, involve the recall of specific facts and events that can be stated or ‘declared’.
• Examples of declarative memory include identifying an insect, explaining a math formula, recalling past meals, and remembering emotional events.
• Declarative memories are often holistic, involving the recall of various aspects of a situation such as time, place, and people present.
• Declarative memory is subdivided into semantic memory, which stores organized factual knowledge about the world, and episodic memory, which contains personal experiences associated with specific times and places.
• Semantic memories are impersonal and consist of specific facts, while episodic memories are personal and involve recalling distinct events from one’s life.
• Episodic memories are more easily forgotten than semantic memories due to the constant influx of new information competing for attention and encoding.

Question 2

The role of episodic and semantic memory in retrieving and constructing events

Answer 2

• On the surface, the distinction between episodic and semantic memories is clear-cut.
• However, some psychologists believe that this is not necessarily the case.
• In recent years, research has suggested that episodic and semantic memories interact not only to retrieve past events but also to imagine future events.
• Semantic and episodic memories are both types of explicit memories.

Question 3

define semantic memory

Answer 3

a type of explicit memory that consists of general knowledge or facts

Question 4

define episodic memory

Answer 4

a type of explicit memory that consists of personal experiences or events
- Episodic memory is often associated with autobiographical events

Question 5

define autobiographical events

Answer 5

personally lived experiences
- when retrieving autobiographical events, you are accessing the information from longterm memory and bringing it into short-term memory

Question 6

Examples of autobiographical events may include:

Answer 6

• your first day of school
• memories from a family vacation
• a birthday party

Question 7

The role of episodic and semantic memory in retrieving autobiographical events

Answer 7

• Autobiographical events are stored in long-term memory and retrieved whenever we think or talk about them.
• Retrieval is the process of accessing stored information from long-term memory and bringing it into conscious awareness in short-term memory.
• Research indicates that the hippocampus is primarily involved in retrieving episodic memories, while the frontal and temporal lobes are involved in retrieving semantic memories.
• Studies suggest that autobiographical memory retrieval activates both the hippocampus and frontal/temporal lobes, indicating an overlap of episodic and semantic memory.
• Autobiographical events contain semantic information (e.g., dates, locations) and episodic components (e.g., personal experiences, emotions), leading to rich and detailed recollection.

Question 8

Retrieving autobiographical events from the past

Answer 8

• The scenario involves a student studying to complete an assignment.
• During the study session, the student adds new information to their existing knowledge.
• The student also remembers specific details of the study session, such as location, start and end times, and interruptions.
• This scenario involves both episodic and semantic memory.
• Episodic memory stores specific personal experiences associated with times and places.
• Semantic memory stores general facts, concepts, or principles related to the assignment topic.
• Autobiographical memories, which combine episodic and semantic elements, are formed from such experiences.
• Autobiographical memories are a type of explicit memory.
• They include sensory details, thoughts, emotions, as well as general event knowledge or personal facts without context.

Question 9

define autobiographical memory

Answer 9

a memory system consisting of episodes recollected from an individual’s life, based on a combination of episodic and semantic memory

Question 10

explain autobiographical memory

Answer 10

• Autobiographical memory encompasses both episodic and semantic components, making it more integrative than episodic memory alone.
• It plays a crucial role in shaping our sense of self and identity by linking past events into a coherent personal history.
• Episodic memory aids in vividly recalling specific past experiences, while reconstruction combines stored information with other details to form a more coherent memory.
• Autobiographical memory is like a container holding both episodic and semantic information, allowing for rich recollection of past events and personal experiences.

Question 11

define reconstruction

Answer 11

the combining of stored information with other available information to form what is believed to be a more coherent, complete or accurate memory

Question 12

The role of episodic and semantic memory in constructing possible imagined futures

Answer 12

• Episodic and semantic memory play roles in constructing imagined future scenarios, referred to as episodic future thinking or mental time travel.
• Episodic future thinking involves projecting oneself forward in time to pre-experience events that might happen in the personal future.
• This ability allows individuals to extract themselves from the present moment and envision hypothetical experiences and situations.
• Future-oriented thoughts, whether abstract or specific, personal or non-personal, are frequently utilized in daily cognition.

Question 13

define episodic future thinking

Answer 13

projecting yourself forwards in time to pre-experience an event that might happen in your personal future

Question 14

define mental time travel

Answer 14

the capacity to mentally reconstruct past personal events and imagine possible future scenarios

Question 15

Some examples of possible imagined futures may include:

Answer 15

• imagining what you’re going to do tomorrow
• imagining how you might present a speech
• imagining yourself in an argument with your parents and considering how it might go and what is best to say
• envisioning what you might wear to a party and
• imagining people complimenting your outfit

Question 16

overview of amnesia

Answer 16

• Autobiographical memories and episodic future thinking share the same brain regions and processes.
• Observations of patients with amnesia revealed their inability to access both autobiographical memories and imagine future events.
• This connection suggests that we construct visions of the future by rearranging memories of the past.

Question 17

amnesia in possibly imagined future

Answer 17

• Functional MRI studies show overlap in brain activity when recalling past memories and imagining future scenarios.
• Episodic future thinking involves actively constructing future events based on past events and knowledge.
• Semantic memory provides context for constructing future scenarios, while episodic memory contributes detailed elements based on personal experiences.
• Damage to the hippocampus can impair both remembering past events and imagining future scenarios.
• Semantic memory helps envision possible scenarios consistent with existing knowledge, while episodic memory adds subjective and detailed elements.
• Imagining possible futures allows for mental simulation of hypothetical events, guiding future behaviors by anticipating consequences.

Question 18

define amnesia

Answer 18

a permanent or temporary, complete or partial loss of memory

Question 19

explain alzheimer’s disease

Answer 19

• Alzheimer’s disease is a neurodegenerative disease characterized by memory decline.
• It involves progressive deterioration of brain neurons, leading to memory loss, cognitive decline, social skill deterioration, and personality changes.
• Alzheimer’s is the most common form of dementia, affecting about 70% of people with dementia.
• It typically starts in older age, affecting about 3% of people aged 65–74 years and 32% of those over 85 years.
• Rare inheritable forms can onset as early as in one’s 30s.

Question 20

define alzheimer’s disease

Answer 20

a neurodegenerative disease characterised by the progressive deterioration of brain neurons, causing memory loss, decline in cognitive and social skills and personality changes

Question 21

define neurodegenerative diseases

Answer 21

diseases characterised by the progressive loss of neurons in the brain

Question 22

define dementia

Answer 22

a collection of symptoms that are caused by disorders affecting the brain

Question 23

symptoms of alzheimer’s disease

Answer 23

• Alzheimer’s disease progresses through three stages: early, middle, and late, corresponding to mild, moderate, and severe symptoms.
• Symptoms include severe memory loss, confusion, impaired attention, disordered thinking, declining social skills, personality changes, and eventually a decline in cognitive functions.
• Initially, patients may experience impaired explicit memory (episodic and semantic), which worsens over time.
• Ultimately, there’s a severe decline in both explicit and implicit memory, along with changes in mood, personality, and language abilities.

Question 24

overview of alzheimer’s disease

Answer 24

• Alzheimer’s disease is currently incurable, and most individuals die within 8–10 years of onset.
• Diagnosing Alzheimer’s disease can be challenging as there is no simple diagnostic test.
• Brain scans, such as computed tomography (CT) or magnetic resonance imaging (MRI), are often used in the standard evaluation for Alzheimer’s disease and other forms of dementia.
• CT and MRI scans reveal brain structure and can rule out other conditions like tumours or strokes that may mask Alzheimer’s disease.
• Additional scans, such as positron emission tomography (PET) and single-photon emission computed tomography, can reveal neural abnormalities associated with Alzheimer’s disease.
• However, these scans cannot definitively diagnose Alzheimer’s disease as they cannot detect microscopic brain lesions characteristic of the disease.
• A definitive diagnosis of Alzheimer’s disease can only be confirmed through a post-mortem examination, where doctors can observe these microscopic brain lesions.

Question 25

define brain scan

Answer 25

an examination of the brain that shows brain activity and tissues that cannot be detected otherwise

Question 26

define lesion

Answer 26

a damaged or abnormal area of the brain that may appear like a scar or wound

Question 27

what happened in Dr Alois Alzheime experient?

Answer 27

• In 1901, Auguste Deter was institutionalized due to unwarranted jealousy, memory impairment, and disorientation.
• Dr Alois Alzheimer, a German psychiatrist, observed, tested, and recorded Auguste’s symptoms.
• Auguste exhibited memory loss, confusion, and nighttime screaming episodes.
• Auguste’s condition deteriorated over 5 years, losing almost all cognitive ability.
• Upon Auguste’s death in 1906 at age 55, Alzheimer performed an autopsy and found extensive brain abnormalities and atrophy in the cortex.
• These findings were unusual for someone of Auguste’s age, leading to the naming of the disorder as Alzheimer’s disease after Dr Alois Alzheimer.

Question 28

Biological causes of Alzheimer’s disease

Answer 28

• Dr. Alois Alzheimer observed significant biological changes in Auguste Deter’s brain, including neuron loss and abnormal protein accumulation.
• People diagnosed with Alzheimer’s disease progress through stages at different rates, but the general pattern of biological change remains consistent.

Question 29

How does Alzheimer’s disease affect the brain?

Answer 29

• A definitive diagnosis of Alzheimer’s disease requires a post-mortem examination.
• Post-mortem examination involves assessing the brain to identify lesions, areas of tissue damage.
• Brain imaging and post-mortem studies reveal lesions predominantly in the hippocampus, providing insights into the biological markers of Alzheimer’s disease.

Question 30

The two primary lesions associated with Alzheimer’s disease are:

Answer 30

amyloid plaques, which are fragments of the protein beta-amyloid that accumulate into insoluble plaques that inhibit communication between neurons

neurofibrillary tangles, which are an accumulation of the protein tau that forms insoluble tangles within neurons, which then inhibit the transportation of essential substances and eventually kill the neuron entirely

Question 31

Researchers have identified four changes in the brain that are characteristic of Alzheimer’s disease.

Answer 31

• Amyloid plaques occur when beta-amyloid proteins build up. This abnormal build-up forms plaques between the synapses of neurons, and so interferes with neural communication
• Neurofibrillary tangles occur when protein builds up inside the neuron and are associated with cell death. This interferes with the flow of information within and between neurons, disrupting communication
• There is a lack of the important memory neurotransmitter acetylcholine. Alzheimer’s disease systematically destroys the neurons that produce acetylcholine
• Brain atrophy occurs. Amyloid plaques and neurofibrillary tangles progressively damage neurons, which die, causing the brain tissue to shrink.

Question 32

define amyloid plaque

Answer 32

an abnormal build-up of beta-amyloid proteins between the synapses of neurons that interfere with communication

Question 33

deinfe neurofibrillary tangle

Answer 33

an abnormal build-up of protein inside a neuron that is associated with cell death

Question 34

define brain atrophy

Answer 34

the loss of neurons within the brain

Question 35

explain the role of the hippocampus in alzheimer’s disease

Answer 35

• The hippocampus is among the first brain structures affected by atrophy in Alzheimer’s disease.
• Up to three-quarters of hippocampal neurons die, impairing the encoding and consolidation of new explicit memories.
• This leads to anterograde amnesia, where individuals struggle to learn new information and may forget recent events or where they placed objects.

Question 36

define anterograde amnesia

Answer 36

the inability to form new explicit longterm memories after an amnesia-causing event

Question 37

explain retrograde amnesia

Answer 37

• Neuronal loss progresses to the cerebral cortex in Alzheimer’s disease, leading to the loss of stored explicit long-term memories (retrograde amnesia).
• This loss includes episodic, semantic, and autobiographical memories.
• Symptoms may manifest as difficulties in recognizing loved ones or experiencing emotional outbursts.
• Loss of autobiographical memories impairs episodic future thinking and the ability to plan for future events.

Question 38

define retrograde amnesia

Answer 38

the inability to retrieve previously stored memories after an amnesiacausing event

Question 39

explain degeneration in neurons

Answer 39

• In the later stages of Alzheimer’s disease, neuronal damage extends to the hindbrain, which regulates automatic functions like breathing and heart rate.
• Degeneration of hindbrain neurons in the final stages of Alzheimer’s leads to death.
• At this stage, the brain significantly reduces in size due to the progressive loss of neurons, as seen in MRI comparisons between normal and Alzheimer’s brains.

Question 40

How does Alzheimer’s disease affect episodic and semantic memory?

Answer 40

• Alzheimer’s disease primarily affects the hippocampus, leading to difficulty in remembering semantic and episodic details of personal events.
• Individuals with Alzheimer’s disease may struggle to plan and construct new future scenarios, impairing social interactions and sense of identity.
• Despite memory impairment, implicit memories, including procedural memory, may remain intact due to their association with the cerebellum.
• Tasks relying on procedural memory, such as playing the piano or following dance steps, may still be performed by individuals with Alzheimer’s disease.

Question 41

define aphantasia

Answer 41

a phenomenon in which individuals lack the capacity to generate mental imagery
- the inability to visualise imagery

Question 42

define mental imagery

Answer 42

the visual representations and experiences of sensory information without the presence of sensory stimuli

Question 43

explain aohantasia

Answer 43

• Aphantasia is a condition where individuals cannot visualise images in their mind, affecting 2–5% of the population.
• Etymology: The term ‘aphantasia’ derives from the Greek word ‘phantasia’ (imagination) with the prefix ‘a-’ (without), meaning ‘without imagination’.
• While mental imagery varies in vividness for most people, those with aphantasia lack the ability to generate mental images altogether.
• The cause of aphantasia is unknown; it can be congenital or acquired later in life.

Question 44

Symptoms of aphantasia

Answer 44

People with aphantasia can describe objects and concepts but cannot experience mental images. This can affect memory, such as remembering the number of windows on a building.

Question 45

Memory and Mental Imagery

Answer 45

Creating mental imagery involves using sensory information from short-term memory transferred to long-term memory, stored in both semantic and episodic memories.

Question 46

Use of Memory in Imagery

Answer 46

People without aphantasia use episodic and semantic memory for vivid mental imagery. For example, imagining a beach scene involves detailed, sensory-rich imagery based on past experiences and general knowledge.

Question 47

Aphantasia and Memory

Answer 47

People with aphantasia cannot visualise episodic memories and lack the visual component in semantic memories. They understand concepts like a beach but cannot generate mental images of it.

Question 48

Challenges with Autobiographical Events and Future Scenarios

Answer 48

Research shows people with aphantasia struggle with recalling autobiographical events and imagining future scenarios. They find it hard to generate mental images of past experiences and future events, making these processes less vivid.

Question 49

Example of aphantasia

Answer 49

A person with aphantasia may know what a beach involves but cannot generate a mental image of a past or future beach holiday, making planning and anticipation less vivid.

Question 50

People with aphantasia might

Answer 50

• struggle to remember or ‘relive’ autobiographical events
• have difficulty imagining future or hypothetical events
• have problems with factual memory
• dream less
• have decreased imagery involving other senses such as sound or touch
• have trouble recognising faces

Question 51

Cause of Aphantasia

Answer 51

The exact cause of aphantasia is unknown.

Underactive Visual Cortex: One theory suggests that brain areas involved in visual imagery, like the visual cortex, may be underactive.

Inaccessible Imagery: Another theory proposes that people with aphantasia might create mental imagery but cannot access it consciously.

Question 52

Forms of Aphantasia

Answer 52

Congenital Aphantasia: Present from birth.

Acquired Aphantasia: Develops after a brain injury or significant psychological event (e.g., depression or anxiety).

Question 53

define visual cortex

Answer 53

the primary cortical region of the brain that receives, integrates and processes visual information relayed from the retinas

Question 54

define acquired

Answer 54

present after brain injury or a significant psychological event

Question 55

No Cure for Congenital Aphantasia

Answer 55

There is no known cure for congenital aphantasia.

Question 56

Therapy for Acquired Aphantasia

Answer 56

Some people with acquired aphantasia have reported regaining imagery abilities after undergoing therapy.

Question 57

aphantasia - Not a Disability

Answer 57

Not a Disability: Aphantasia is not considered a disability but a unique variation in human experience.

Question 58

aphantasia - Success and Occupations

Answer 58

Studies suggest aphantasia does not inhibit success. Many people with aphantasia, including doctorate students, engineers, and other professionals, lead normal lives and may not even be aware they experience the world differently.