Retrieval of Memory Flashcards
What does the DMN do when you are focused on a hard externally oriented task?
Deactivates relative to baseline
Why do source memory tasks activate ventrolateral PFC?
There is competition between sources -> judgement you’re making about the size and object are semantic
Which of the following does NOT cause strong interference between memories?
Competition memories which is highly meaningful -> as usually reduces the competition you have memories (basis of the level of processing effect -> think about the meaning of words, it tends to improve memory by reducing competition because it encodes items in a more distinctive fashion)
What type of interference occurs when new learning makes older memories inaccessible?
Retroactive
What circumstances promote false memories?
When there is competition e.g. from semantic knowledge
Why does damage to the hippocampus not promote false memories?
because if it’s already damaged retrieving memories will be hard anyways
What type of semantic impairment is associated with false memories?
Semantic Aphasia
What two deficits are associated with confabulation?
Poor control of memory and a meta-cognitive deficit
Why is retrieval induced forgetting helpful?
Reduces need to control retrieval of target item
Overtime, where may episodic experiences transfer to?
temporal neocortex
-> semantic hub in the anterior temporal lobe
How are memories retrieved?
often spontaneously
how is retrieval from strong cues?
automatic (due to spreading activation)
how is retrieval from weak cues?
can be effortful and we can struggle to separate memories
what was the DMN originally described as?
task negative network / believed to originally deactivate during a demanding task
what are the components of the default mode network?
incl hippocampus, angular gyrus, medial pfc and posterior cingulate
The DMN is implicated in?
spontaneous thought and episodic recollection (/recollective experience)
what happens to the DMN during a difficult task?
often deactivates to support memory retrieval
-> trying to do this during a difficult sensorimotor task, it will interfere with task performance so you might suppress this network deliberate during a non-memory based task
-> if you’re doing a memory task, this network may allow you to do that task
when are regions of DMN active more?
when focused memory on memory -> dependent on the task
what does DMN support?
deliberate and accidental memory retrieval
What did Christoff et al. (2009) find?
more DMN activity during a task where people reported their mind had wandered
Brain Map
Red regions are task positive regions -> show an increased response on a demanding sensory motor task -> this is also important for memory as tends to be switched on during encoding
- Red (encoding) -> Blue (Retrieval -> DMN)
what does episodic memory overlap more with?
episodic memory overlaps with DMN more than semantic memory
Why does episodic memory overlap with DMN more than semantic memory? (Vatansever et al. (2021))
- contrast people making episodic and semantic decisions about word pairs
- in episodic task -> if you contrast that with semantic task, you see more activation in areas of the DMN (posterior cingulate and angular gyrus)
whereas, if you everse contrast and you look at semantic decisions over episodic, you get a different set of areas including the ventrolateral PFC (important for memory control)
what is episodic memories about?
recently formed memories
what is semantic about?
making decisions about something you have gained knowledge about over a life-time ago
Vantansever et al. (2021) manipulated difficulty of episodic and retrieval tasks in similar ways (comparing strong and weak memories across tasks).
- made semantic tasks harder by asking people to make decisions about word pairs, with rarely co-occur (i.e. dog-bone (easy) vs. dog-beach (takes some thinking to see them together)
- episodic presented many learning tasks (lots of opportunities to learn the two words are going together in an episodic memory paradigm, then you make it easy to retrieve that information later) vs. making the decision more difficult by showing the individual a word pair only one
What did they find?
- same brain regions were important for easy decisions over hard
- DMN was implicated in both semantic and episodic retrieval when it was relative easy
- Angular gyrus and posterior cingulate might be important in relatively automatic patterns of retrieval from both memory stores
- WHEN WE LOOK AT HARD OVER EASY: we found VLPFC area (same region playing a role when you’re controlling retrieval from both semantic and episodic memory)
what is DMN involved in?
not only episodic recollection but also more automatic semantic retrieval
* DMN is recruited when memories are strong and come unbidden to mind (doesn’t take a lot of retrieval effort)
Where is the VLPFC located?
in the ventral and lateral part of the prefrontal cortex.
when is the ventrolateral PFC recruited?
during both episodic and semantic retrieval when task-relevant information is weaker
-> VLPFC when together with other regions in a large scale network is recruited when both episodic and semantic retrieval is more challenging when perhaps the information relevant to your goal is weakly encoded and therefore hard to recover
what issues do we have with retrieval?
we have many similar memories that interfere with each other
-> we must control competition between memories
what engages when we have to control competition between memories?
VLPFC
what is proactive interference?
old learning interferes with new learning
-> many similar memories generate strong competition
what is retroactive interference?
new learning interferes with old memory
what conditions maximise interference between memories?
- competing memory was presented recently
- competing memory is very similar to target
- there are many competitors
the VLPFC plays a critical role in what?
control of memory
but what is VLPFC also important for
selective coding and selective retrieval
what are other names for the ventrolateral PFC?
Left Inferior Frontal Gyrus (anatomical terms) or Broca’s area (tends to be in language studies)
what can the VLPFC biases?
processing towards the representation that is relevant for your goal/conext
-> mechanism allowing you to prioritise some memory representations over others as you go forward
how does encoding of memory work?
you have the capacity to use attention to guide the encoding of memory
-> but if you don’t pay attention, you won’t remember later
Subsequent Memory Effect
Research has looked at the basis of memory retrieval, using a paradigm called the subsequent memory effect
* Look at which brain regions during encoding predict subsequent memory success
* Scanning while they encode the information and then ask them the information they have encoded afterwards
* Can predict later success in memory task based on how much activation you see during encoding
Where does brain activity at encoding predict subsequent memory success?
VLPFC and Hippocampus (/Parahippocampal Gyri)
-> Hippocampus predicts subsequent memory encoding because the change things/generate activity in order to form an episodic memory that can be remembered later
-> PLIFG also predicts sequent memory encoding, important for predicting memory based on the way it can direct our attention to important aspects of our experience to allow selective coding of that information
-> VLPFC directs attention to important aspects of experience
* Attention to features that make it into your memory, as opposed to the memory system itself
if those with amnesia were doing the subsequent memory task, what would we find?
hippocampal response will be eliminated but VLPF response will still be there -> still engage attentional systems in memory in a relatively normal way even if they don’t really encode much information about what is going on