Weeks 10-11 Alex Kafkas Flashcards
Outline the function-structure relationship.
Function and structure do not match exactly.
A structure can participate in multiple functions and a function may rely on multiple structures.
It’s not a 1 to 1 relationship between them.
What are the three overarching terms for the definitions of episodic memory?
Mental time travel.
Links.
Time and Place.
They are not mutually exclusive, they define different parts of episodic memory.
What is the ‘mental time travel’ definition of of episodic memory?
It’s Tulving’s definition.
It emphasises the first person mental time travel component of episodic memory, the role it has in re-experience of memories.
What is the ‘links’ definition of episodic memory?
The ability to create links between unrelated bits of information, making a coherent episode - emphasis on the relational component of memory.
What is the ‘time and place’ definition of episodic memory?
Placing a past experience within a particular time and place - with emphasis on context.
Summarise episodic memory holistically.
It is the result of associative learning.
The what, where, when and who of an episode (its context) are associated and bound together.
They can be retrieved (and re-experienced) as a singly episode.
Autobiographical, personal memory.
What does MTL stand for and what are the 3 MAIN substructures within it?
Medial Temporal Lobe.
- Hippocampus.
- Entorhinal cortex.
- Parahippocampal gyrus.
What are the three cortical subsections of the parahippocampal gyrus?
Rhinal Sulcus
Perirhinal Cortex
Parahippocampal cortex
What role are the structures inside the MTL thought to be an important part in?
The formation and retrieval of episodic memory.
What are the 3 main components of the hippocampus?
Dentate Gyrus
Cornu Ammonis (CA)
(CA1, CA2, CA3, CA4)
Subiculum
Describe the information flow within the MTL.
Organised hierarchically
Information is initially collected through the perirhinal and paraphippocampal cortices.
It then passes to the entorhinal cortex and ultimately reaches the hippocampus.
The cortical regions do no simply funnel information to the hippocampus.
A large network of connections both within and among the subregions of the MTL cortical regions perform extensive information processing.
Name the components of the “extended MTL” system. (4)
These are systems that the MTL works with.
Fornix
Anterior thalamic nucleus
Mammillary body
Medial prefrontal cortex
(Medial temporal lobe:
Amygdala
Hippocampus
Perirhinal cortex
Entorhinal cortex
Parahippocampal cortex.)
What are usual causes of amnesia? (5)
Neurosurgery (patient HM)
Strokes
Head injury
Certain viruses
Symptom of long term alcoholism.
What are the two types of amnesia and what deficits do they present?
Anterograde: (most common)
- Difficulties acquiring new memories.
Retrograde:
- Difficulties remembering events from before their brain injury.
Give a brief overview of the details of HM and his surgery.
Suffered from severe, intractable epilepsy.
Foci in both medial temporal lobes.
Treated with a bilateral medial temporal lobectomy.
Included removal of the hippocampus and amygdala.
(a focus (foci) refers to the origin point of a disease or condition)
What were the pros and cons to patient HM’s surgery?
PROS:
- Reduced the severity and frequency of his convulsions.
- Improved his IQ from 104-118
CONS:
- Minor retrograde amnesia
- Profound anterograde amnesia: could not form LTM’s for events post surgery.
Which areas of brain was patient HM missing post surgery?
Amygdala, hippocampus, perirhinal and entorhinal cortex were missing.
Anterior portion of MTL missing.
What did the digit span +1 test reveal about patient HM?
After 25 trials, HM could still not successfully repeat more than 7 digits.
Shows that the problem was transferring STM to LTM - therefore his STM was fine, it is somewhere in the LTM that the deficit is.
What did the mirror drawing task reveal about HM and memory in general?
He was asked to draw a picture using a mirror - very bad at first.
Over time he improved his performance although he thought he was approaching the task for the FIRST time every day.
CONCLUSION:
- There is a difference between explicit (declarative) and implicit (non-declarative) memory.
Describe the subsequent memory paradigm.
Investigates brain activity differences between successful and unsuccessful memory formation.
METHODS:
- Study Phase: Participants view items (words, images, etc.).
- Test Phase: Participants try to remember the studied items.
- Analysis: Brain activity (e.g., EEG, fMRI) during the study phase is sorted based on whether items were later remembered or forgotten.
RESULTS:
- Identifies brain regions and patterns that support memory encoding.
What did Wagner et al. (1998) discover in their remembered vs forgotten stimuli study?
They asked: does the brain activity at encoding predict which items are later going to be recognised and which will be forgotten.
RESULTS:
- Activity in the left ventrolateral PFC and the left MTL was predictive of later remembered stimuli vs forgotten.
What is familiarity?
The sense of memory that a stimulus has been encountered before.
What is recollection?
A memory for the context or other associative information about a previous encounter with a stimulus.
According to the model proposed by Eichenbaum et al. (2007), what are the roles of the 3 major parts of the MTL in memory?
Perirhinal cortex:
- Processes item representations (important for familiarity)
Parahippocampal cortex:
- Assumed to process “context” (including sense perception).
Hippocampus:
- Binds items in context (important for recollection).
What does the modern view of the MTL suggest?
Functional specialisation within the MTL in relation to processes such as familiarity compared to recollection.
Describe the Ranganath et al. (2004) study that measured familiarity and recollection
METHODS:
- used the subsequent memory paradigm to measure familiarity and recollection.
- Familiar: If they fail to remember the colour that the word was presented in (as they didn’t recollect the context).
- Recollection: If they remember the word and colour.
RESULTS:
- As familiarity recognition confidence increased, so does perirhinal cortex activity.
- Recollection-based recognition was predicted by activation in the posterior hippocampus.
SUPPORTS FUNCTIONAL SPECIALISATION
Describe the Kafkas et al. (2017) study into familiarity and recognition in the MTL at retrieval.
METHODS:
- Subsequent memory paradigm.
- Exposed to different visual stimuli.
- Inside the fMRI they performed the familiarity/recollection task.
RESULTS:
- Hippocampus was always active during recollection independently of stimulus type.
- Rest of MTL was elicited by familiarity.
