5C

• Semantic memory


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


  a type of explicit memory that consists of personal experiences or events
• Autobiographical events


  personally lived experiences
• Retrieval


  the process of accessing information that has been stored in long-term memory and bringing it into our conscious awareness in short-term memory
• Semantic and episodic memories are both types of explicit memories. Semantic memory consists of general knowledge or facts whilst episodic memory consists of personal experiences or events. Episodic memory is often associated with autobiographical events, which refer to personally lived experiences.
• These autobiographical events are stored in long-term memory and are retrieved every time you think or speak about them. Retrieval is the process of accessing information that has been stored in long-term memory and bringing it into our conscious awareness in shortterm memory.
• Research shows that the hippocampus is primarily involved in the retrieval of episodic memories and that the frontal and temporal lobes are involved in the retrieval of semantic memories

  However, studies have found that the retrieval of autobiographical events involves the activation of both these brain areas, suggesting that autobiographical events involve an overlap of episodic and semantic memory
• why autobiographical events activate both sematic and episodic memory -

  This may occur because autobiographical events contain information that is semantic, such as the date or location of the event. Additionally, autobiographical events also contain episodic components, which are more specifically related to the personal experience of the event, such as recalling the feeling of being nervous or happy during the event. The episodic component of autobiographical events allows for the event to be remembered in rich detail.
• Possible imagined futures


  hypothetical experiences and situations that an individual has the ability to create and conceptualise in their mind
• Episodic and semantic memory are also involved in constructing possible imagined futures, which refer to hypothetical experiences and situations that an individual has the ability to create and conceptualise in their mind.

  Some examples of possible imagined futures may include

  • imagining what you’re going to do tomorrow
• The brain regions that are involved in the retrieval of autobiographical memories are also activated when people construct possible imagined futures. Schacter et al. (2008) found that patients who sustained damage to their hippocampus not only experienced difficulty remembering past events, but also struggled to imagine future scenarios. This is because when individuals attempt to mentally construct a possible imagined future, they draw on elements of past experiences from their semantic and episodic memory.
• Semantic memory is involved in the construction of possible imagined futures as individuals must be able to envision possible scenarios that are consistent and fit in with what they already know about the world. Episodic memory is also involved by allowing individuals to construct a possible imagined future that is subjective and includes more richly detailed elements, such as the people involved or emotional reactions.
• Neurodegenerative diseases


   diseases characterised by the progressive loss of neurons in the brain
• alzheimer’s disease


  a neurodegenerative disease that involves the progressive loss of neurons in the brain and is characterised by memory decline
• Neurodegenerative diseases are diseases characterised by the progressive loss of neurons in the brain. Alzheimer’s disease is an example of a neurodegenerative disease that is characterised by memory decline
• Some symptoms of Alzheimer’s disease include:

  • a decrease in cognitive functions, such as the ability to plan, problem-solve, and think logically.
  • personality change. • changes in mood and emotion.
  • frequently becoming confused or disoriented.
  • difficulty with language and communication.
• s, a conclusive diagnosis of Alzheimer’s disease can only be made through a post-mortem examination. A post-mortem examination is an assessment of a dead body that occurs to determine the cause of death. From a post-mortem examination, lesions, which refer to an area of tissue that has been damaged due to disease or injury, can be examined through neuroimaging. Therefore, what we know about the biological markers of Alzheimer’s disease largely stems from brain imaging and post-mortem studies
• The two primary lesions associated with Alzheimer’s disease are:

  • 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.
• At the later stages of Alzheimer’s disease, the brain can be observed as having significantly reduced in size due to a loss of brain matter which is attributed to the progressive loss of neurons
• How does Alzheimer’s disease affect episodic and semantic memory?

  As damage can be associated with the hippocampus, patients with Alzheimer’s disease may struggle to remember semantic and episodic components of personally experienced events. Additionally, a study found that individuals with Alzheimer’s disease lacked the capacity to draw on episodic and semantic memories in order to plan and construct new future scenarios.
• Aphantasia is a phenomenon in which individuals lack the capacity to generate mental imagery. Mental imagery refers to the visual representations and experiences of sensory information without the presence of sensory stimuli. Mental imagery can vary in details and vividness, however, those with aphantasia describe themselves as not having the power to generate mental imagery altogether
• When creating mental imagery, individuals use sensory information that has been organised in short-term memory and then transferred to long-term memory to recreate perceptual experiences. This sensory information can be stored in both our semantic and episodic memories. People without aphantasia are likely to draw on both episodic and semantic memory when creating mental imagery.
• people with aphantasia may not be able to visualise richly detailed and vivid episodic memories due to their inability to generate mental imagery. Additionally, while semantic memories may remain intact, the visual component of these memories may also be lacking.