Problem 2 Flashcards
Medial temporal lobes
Refer to the inner surfaces of the temporal lobes that contain the
a) HIPPOCAMPUS
b) entorhinal cortex
c) perirhinal cortex
d) parahippocampal cortex
e) amygdala
Episodic memory
Refers to a memory for a specific event, that includes its spatial + temporal info
ex.: first day of school
- -> “what we REMEMBER”
- -> Hippocampus activity is essential
Semantic memory
Refers to a memory for facts, general + personal knowledge about the world
ex.: own name, favorite food
- -> “what we KNOW”
- -> survives hippocampal damage
What do episodic + semantic memories have in common ?
- Can be COMMUNICATED flexibly
- -> formats may be different from the way they were acquired - Consciously ACCESIBLE
- -> knowing info is there, ready to be used
In which way are episodic + semantic memories different ?
- EM is tagged with a spatial + temporal context, SM not necessarily
- EM has to experienced personally, SM can also be general info
- EM is learned in a single exposure, SM can also be strengthened by repeated exposure
- EM concerns specific events, SM concerns factual info
Declarative memory
What
Reflects the fact that it is easy to verbalize (declare) your knowledge
–> broader term for semantic + episodic memory
Non-declarative memory/ Procedural memory (How)
Shown by performance rather than conscious recollection
a) skill learning
b) classical + operant conditioning
c) priming
d) non associative learning
–> not always consciously accessible or easy to verbalize
ex.: riding a bike
Explicit memory
Knowing that you have information that is accessible and can thus be used when needed
–> includes declarative memory
Implicit memory
Memory that occurs without the learners awareness
–> includes non-declarative memory
What are the three possible explanations on which memory developed first ?
(Episodic or semantic)
- One has to have a certain amount of SM before EM can built on this framework
ex. : Have to know what a prom is before knowing that you went to a prom - SM represents info we have encountered repeatedly from EM
- EM + SM are fundamentally interdependent
- -> each can affect the other
Can nonhumans have episodic + semantic memory ?
- The experiment of the “radial arm maze” with rats showed that they were able to remember where the food was and use this info flexibly
Conclusion: semantic memory
- The gorilla was able to remember which specific type of fruit he ate, who gave it to him + when it happened
Conclusion: “episodic-like” memory
Why is the term “episodic-like” memory used for nonhumans ?
It acknowledges that we cannot directly ask nonverbal animals about their subjective sense of self or their ability to perform “mental time travel”
What are the 3 basic principles that govern how successfully a new EM or SM is encoded/stored in memory ?
- Mere repeated exposure to info doesn’t guarantee memory
- New info is easier to remember if you can relate it to things you already know
- Deeper processing at encoding improves recognition later
Levels-of-processing effect
The more deeply you process new info during encoding, the more likely you are to remember the info later
–> fMRI shows that brains are much more active during deep-processing than superficial processing
Tip-of-the-tongue phenomenon
Inability to retrieve stored info, where info is temporarily inaccessible
–> one usually succeeds in retrieving info when turning ones attention elsewhere
Transfer-appropriate processing effect
Retrieval is more likely to be successful if the retrieval conditions are similar to encoding conditions
ex.: objects presented as words, are tested as words not for ex. pictures
Free recall
Memory task in which one is asked an open-ended question, and one is required to supply the answer from memory
Cued recall
Memory task in which one is given some kind of clue to the correct answer
ex.: what is the latin word for arch: F___
Recognition
Memory task in which one has to pick out the correct answer from list of possible options
–> multiple choice
Desirable difficulties phenomenon
The idea that “difficult” learning conditions, meaning the ones that challenge your ability to recall, promote better memory of the info being recalled
Consolidation period
Most forgetting occurs in the first few hours or days after learning
–> info that survives the critical first few days might last in memory indefinitely
Directed forgetting
Occurs when info is forgotten on demand
–> suggest that we may have more power over what we remember than we think
The role of “Interference” on LTM
When 2 memories overlap in content, the strength of either or both memories may be reduced
Proactive interference
Old info can disrupt new learning
–> breaking habits
ex.: Phase of mistakenly using the old password when it was renewed
Retroactive Interference
New info can disrupt old learning
ex.: Inability to remember old password, when having mastered to remember new one
Source monitoring error
Remembering information but being mistaken about the specific episode, which is the source of that memory
–> semantic content is preserved, episodic content distorted
ex.: thinking one has built a nice sentence by oneself when indeed, one was just retrieving a sentence previously seen in a book from memory (unintentional plagiarism)
Diese-Roediger-McDermott Paradigm
DSM
People are asked to learn lists of words, where the words all share a particular implicit theme.
The participants correctly identify studied words + reject unrelated words
–> BUT: clim to recognize the theme word even though it wasn’t on list
What might explain the DSM paradigm ?
Source monitoring
- People encode the meaning of the words (theme) and form a memory by thinking about it
- Then they mistakenly remember having encountered the word on the list
False memory
Memory of events that never actually happened
–> likely to occur when one is prompted to imagine details, which is then falsely remembered as the truth
Why is the loss of a single brain cell NOT dramatic for the maintenance of memory ?
We have networks of neurons that respond primarily to info representing simple, familiar categories
–> this way all memories would only be lost if the whole network would be affected
Anterograde amnesia
A severe loss of the ability to from new episodic + semantic memories
Is the hippocampus critical for forming new semantic memory ?
NO,
encoding of new semantic memories depends primarily on the Parahippocampal + Perirhinal cortices than on hippocampus
BUT: A functioning hippocampus is critical for forming new EMs
What kind of activity does the Hippocampus show in memory tasks like DSM ?
- Initial encoding of words that would be subsequently remembered
–> less activity for words that were subsequently forgotten
- High activity for studied list words AND unstudied theme words in DSM
- -> explains false recognition
Which brain region is able to correctly distinguish true episodic memories from false ones ?
A small area in the parahippocampal cortex
–> only fires when presented with studied words, NOT unstudied theme word
Retrograde amnesia
Graded vs. flat
Loss of memories of events that occurred before the injury
Graded: better memory of memories lying in the far past
Flat: No difference in recent vs past memories
Ribot gradient
Retrograde memory loss is worse for events that occurred shortly before the injury than for events that occurred in the distant past
Standard consolidation theory
- Hippocampus + MTL structures are required for the initial storage + retrieval of the EM
- EM consists of different components stored different areas of the cortex
- With time, the components can form direct connections with each other
- -> help of Hippocampus is no longer required
=> hippocampal activity is strongest for recently acquired info (Graded retrograde amnesia)
Multiple trace theory
MTT
- When an event is experienced it can be stored as an EM by an ensemble of neurons in the hippocampus + neocortex
- Each time the memory is retrieved, the retrieval itself becomes a new EM
- Hippocampus is essential as it stays part of the connectivity between the EM components even after they consolidate
=> hippocampal activity is the same for recent + old infos (Flat retrograde amnesia)
How does MTT explain the difference between EM + SM ?
- EM always come first
- SM are the results of experiences that have become detached of the rich contact in which they were acquired (EM)
- SM do not require the hippocampus
Amnesia
- Inability to learn new things or loss of previous knowledge
- Losses may differ for LTM or STM
- The farther posterior in the Medial temporal lobe the damage is, the worse the amnesia
- Can acquire SM, not able to acquire EM
H.M.
His medial temporal lobes were removed bilaterally, in order to minimize the seizures mediating + interrupting his everyday life
–> resulted in Anterograde amnesia coupled with partial Retrograde amnesia
BUT: He had normal STM + signs of non-declarative memory
Korsakoffs syndrome
Form of Amnesia, associated with long term alcohol abuse, that leads to vitamin deficiencies
–> degenerated diencephalons, especially mammilary bodies + dorsomedial thalamus
K.C.
Developed source amnesia after severe head injury
–> BUT: Intact semantic memory which showed that SM + EM are independent from one another
Source amnesia
Not remembering the source/episode in which the information was learned
What does damage to the Medial temporal lobe structures or the midline Diencephalon lead to ?
- Graded retrograde amnesia
- If hippocampus isn’t affected, one may still be able to form new EMs
- Implicit + explicit memories will still stay intact
- -> suggests that their processes rely on different brain stems
Priming
Refers to a change in the processing of a stimulus as a result of prior exposure to the same stimulus
ex.: When presented with the letters MOT___, one will complete the word into MOTEL when having viewed the word previously
Which role do the MTL structures play in the consolidation of memories ?
The provide a binding area for multiple cortical regions involved in the initial encoding of the memory (“Relay station”)
–> thus if damaged, new memories cannot be formed
M.S.
Lesions to the visual cortex
–> could form non-declarative but no declarative memories
