L09 - Memory Flashcards
What is the history of memory?
When we try to understand something, we often look back and look at our history (i.e.) is there a god for this?
Spiritual explanations
Egypt – Thoth – god of learning memory, wisdom, scribe of the gods.
Greece – Mnemosyne – Goddess of memory. Mother of the muses.
Greece – River Lethe
The river of forgetfulness
Runs through Hades – where gods go when they die
Drink from a specific river to go to Hades
Rome – Minerva Goddess of learning, memory and wisdom
What is memory?
Everything that makes us human and defines you as a human being as well as how you see yourself is MEMORY
When it’s gone, you cease to exist
How is it possible that we keep experiences around; we can teach someone something and five days later they are able to do it
Retain a skill they could not do before
What is it in the nervous system that changes for this to happen? How does it change? Is it encoded in our DNA?
What do we think when we see “the brain as a computer?
The brain is nothing like a computer but this is what is more natural to us. For the Greek, it was Gods.
The brain as a computer would look like
Information-processing perspective: “Brain (and so memory) is like a digital computer.”
- Processes (how are memories created, maintained, revived?)
- Encoding, Storage, Retrieval, Recall
- Hardware
Representations – what is stored, retrieved, recalled
- A memory representation (memory trace, memory record) is a unit of information, that can be processed.
- Software
Structures – Where are memories stored, retrieved from/to, recalled from/ to?
- Short-term store: like RAM of computer – restricted capacity; holds information for a short time.
- Long-term store: like the hard disk of a computer – nearly infinite capacity; holds information almost forever
How would you describe the hardware if we are comparing the brain to a computer?
Info – Auditory, Visual, Tactile etc.
Code – Relatively faithful
Capacity – large but limited
Duration – most info decays within seconds and is permanently lost
How would you describe the short-term memory if we are comparing the brain to a computer?
Code – acoustic, linguistics
Capacity – small
Duration – indefinitely if rehearsed, decay within 18-30 seconds if not continuously rehearsed.
How would you describe the long-term memory if we are comparing the brain to a computer?
Code – semantic?
Capacity – unlimited?
Duration – indefinitely?
Who is Henry Molaison (HM)?
This was the beginning of our modern explanation on how the memory and brain are related and work together.
Point of origin of modern memory research
HM had severe epilepsy (about 10 seizures per day). This was dangerous so he had surgery to the hippocampus (origin of epilepsy)
What surgery did HM go through?
He had a bilateral hippocampectomy (removed both hippocampus) to treat his epilepsy
Led to grading retrograde and amnesia for episodic memories (hippocampus is the center for episodic memories)
What is the mirror tracing experiment?
HM would not remember that he did this test the day before ever but he always got better
↳ We know where the brain is not working anymore → took out the hippocampus
↳ Implies: if you want explicit memories, you need a hippocampus
This case is so important because we had completely perfect characterization of what he could and could not do without the hippocampus
What was impaired after HM’s bilateral hippocampectomy?
Episodic memories – formed “on the fly” (made automatically) (Ex. What you ate for breakfast)
Recognition memory for recent objects and places
Explicit memory tasks
*Ex. Seven seconds reset man
What was preserved after HM’s bilateral hippocampectomy?
Semantic memory (do not lose knowledge about the world)
Priming
Procedural memories (mirror tracing experiment, riding a bike…)
Conditioning (dog, bell, treats (works with human that do not have a hippocampus))
Implicit memory tasks
What is declarative memory?
Hinges on hippocampus
Allows us to consciously recollect events and facts
Episodic memory
Semantic memory
What is non-declarative memory?
accessed without consciousness or implicitly through performance rather than recollection
Does not hinge on the hippocampus
Accessed without consciousness or implicitly through performance rather than recollection
Procedural memory
Priming
Classical conditioning
Non-associative learning
What is plasticity?
A change in neural morphology as a response to environmental stimuli
The brain is not hardwired, but able to respond to adaptive pressure by changing its structure and fundamental organisation
What is synaptic plasticity?
Refers to the phenomenon that the morphology of connection between neurons can change as a function of experience. This form of plasticity is thought to form the neurobiological basis of learning and memory formation
Memories are made by changing the structure of the synapses.
AMPAR channel – Sending signals to change the synapses to increase the number of connectors at the synapses.
What is cortical plasticity?
Refers to the phenomenon that cortical organisation can change in response to brain injury, such as strokes, lesions, etc…
This involves synaptic plasticity to some extent
Neuron controlling right are die but other areas in the brain that are functional take over that function (get “recruited” to control right arm)
What are the normal sensory perceptions of where something is coming from?
Occipital areas receive predominantly visual input
To a lesser extent also received tactile and auditory input
What are the sensory perceptions when there is visual deprivation involved?
When visual input is blocked for prolonged periods (ex. 2 weeks), the occipital lobe receives no more visual stimulation
This means that the auditory and tactile stimuli recruit more processing resources from the occipital regions than before
What is the law of regression?
Instable memories are more likely lost that stable ones.
What are the areas that process sensory stimuli?
Auditory, visual and tactile cortex – where memory is held
What is amnesia?
Memories that are lost are the most recent ones (typical cases)
Past memories stay intact when you have amnesia, you do not lose many.
Very strong amnesia however when you are trying to make new memories
Cannot recover them
New memories are not stable
What is the Perseveration-Consolidation hypothesis?
Repeating something to yourself multiple times will help you remember
If you are interrupted, you are most likely to forget them.
What is the current consolidation “dogma”?
Memories are labile after acquisition and are fixed (i.e.) permanently stored (consolidated) over time.
Consolidated memories are stable and can persist long-term
Consolidation is a transient, unidirectional process that occurs only after acquisition
Disruption of consolidation impairs memory formation and therefore reduces what will be retained.
What is the Synaptic (or cellular) consolidation hypothesis?
What behavioural neuropsychologists use
They encode new memories
Learning leads to changes in the connections between neurons
These modifications are unstable at the beginning, shortly after learning.
In order for long-lasting memory to form, the synaptic modifications need to stabilize.
The process that stabilizes these changes is called synaptic consolidation
What is the System consolidation?
What cognitive psychologists use
Can explain HM phenomenon – need hippocampus for new memories (episodic memories)
Certain types of memories (e.g., memories of events) initially require the hippocampus.
Over time, these memories undergo a transformation in terms of which brain structures are mainly involved for their expression. This process is called systems consolidation.
During systems consolidation, the expression of these memories will involve the hippocampus less and less, but more and more frontal areas
What is the spine remodelling during learning?
Conditioning increases the amount of spines on a neuron (synapses) in the hippocampus
After training, you see a shift in spine density (more spines); more connections between neurons
Learning induces change to the synaptic connections between neurons
Synaptic consolidation probably works on these changes and probably stabilizes and optimizes over time
Post synaptic density – part of the dendrite spine (top part)
What is Long-term potentiation?
“LTP [is an] experimental [phenomenon], which can be used to demonstrate the repertoire of long- lasting modifications of which individual synapses are capable.”
Experimental approach
Neuron is capable of changing its synaptic connection in light of stimulation
Note: Long-term depression represents the opposite effect, a decrease in the likelihood that the post-synaptic neuron will fire given a certain stimulation intensity.
Hebbian Learning
Hebb’s STM-LTM model
Psychology is a biological science – finding how neurons and synapses from memories. Argues that neurons firing themselves as an ongoing activity makes memories
What Hebbian learning supports the short-term memory model?
The pattern can stay active on its own for a while after the experience.
Recurrent connections among neurons of the cell assembly keep the pattern activated in a short-term.
What Hebbian learning supports the long-term memory model?
After a while, recurrent activity leads to changes in the synapses of the cell assembly.
As a consequence, the pattern can be recreated at a later time as a long-term memory.
What Hebbian learning supports the long-term memory model?
After a while, recurrent activity leads to changes in the synapses of the cell assembly.
As a consequence, the pattern can be recreated at a later time as a long-term memory.
What is the standard model of system consolidation?
Hint - How are they [your senses] kept coherent (you don’t have disconnected experiences for smell vs. Touch etc. It is all the same)
The brain has very little connection between cell assemblies (anatomical feature). The HIPPOCAMPUS connects all senses to make one experience in your memory. Take out the hippocampus, you will never have memory of this (nothing binds the aspect of the experience together)
All disconnected = no memory. Something allows the disconnected areas to connect. Hippocampus reactivates these regularly. The more you reactivate the memories, the more likely they are to find DIRECT CONNECTIONS between themselves [senses]. A memory with the hippocampus is much more vivid/spatial/more like a real event being experienced.
What are the three models for system consolidation?
Standard Model of system consolidation
Extended Standard Model of system consolidation
Multiple-Trace model
These are all only models; we still do not know what happens
What is a schemata?
Over time, memories are re-shaped; something to do with youth. Youth influences what we will remember and now we would use memories.
Repetition is interesting because repetition is using memory and using memory changes them (recalling them modifies them
What are the types of distortion caused by schemata?
Omission
Rationalization
Transformation
What is omission? Hint - type of distortion caused by schemata.
Forgetting of unfamiliar material
What is rationalization? Hint - type of distortion caused by schemata.
Attempts to increase coherence, also by considering present knowledge about the subject matter
Things that don’t make sense to you, each time you use the memory you try to make it more coherent to what you know
Rationalize; make it that way to keep your knowledge about the world
That schematic knowledge determines how new knowledge is created and how it will change.
What you learn will be modified by what you know.
What is transformation? Hint - type of distortion caused by schemata.
Attempts to change the unfamiliar into the familiar
Having no background knowledge for something makes it hard to acquire new knowledge
Schematic knowledge can affect the way you see and how you interpret what you see
The more you know, the more biased you will be.
What is the frame theory?
You select a template [frame] of what you think the new knowledge fits into. What will likely happen in this situation?
Ex. Stereotype situation
Child birthday party – you imagine there will be clowns and bouncy castles and things like that; that is a frame.
What is a script?
A memory structure for encoding general knowledge of a certain situation action routine.
Imagine you remember going to a restaurant with someone and you think you remember exactly what happened: but really you don’t, your mind just “fills in” what it thinks happened because that is what usually happens but maybe it was not that way
What is the inducing of false memories?
How you word something or express something can change the memory of the event.
Ex. Using different words like; smashed, collided, bumped, hit or contacted – while talking about a car crash makes you believe that the car crash was (i.e.) worst when using the word smashed and not so bad when using the word bumped.
This is an induction of a false memory
What is the influencing scene recognitions?
People saw slides of a car stopping at a yield sign but were asked a couple of questions one of which was “did the car stop at a stop sign” and even though the car stopped at a yield sign, the people thought it was a stop sign since it would make sense.
The question changed their memory
Once you believe you saw a stop sign, you cannot change your memory to thinking you saw a yield sign.
What is the “Reconsolidation effect”?
RETRIEVAL CAN RETURN MEMORIES [consolidated memories-supposed to be stable] to a state like the state that they had just learned the memory
What is Propranolol and how does it help in people in psychology?
You retrieve a long-term memory that is supposed to be consolidated and you return it to a state of liability (this is similar to when you just learned the memory)
People with PTSD can be treated like this
Reactivating their fear and while you are retrieving it, you get a drug named propranolol
Propranolol binds to the receptors in the amygdala where the fear is processed and PTSD patients can lose the emotional aspect of this memory
Can also be used to cure people’s phobias
Impair, tone down or reduce the fear that one will have
What happens if you mess with a memory for the hour that it is consolidating?
You will likely have amnesia for that memory
If you mess with this process you will likely have impairment (Anisomycin)
You would have to have consolidation again [reconsolidation ]
For a lot of older memories, it does not work like that
What is the negative prediction error and what does propranolol do?
Rat expects a shock when he enters a box but does not receive it
Propranolol REDUCES fear in this case
What is the no prediction error and what does propranolol do?
Rat expects a shock when he enters the box and he receives it
Propranolol has NO EFFECT on fear in this case
What is the positive prediction error and what does propranolol do?
Rat does not expect a shock when he enters the box but he receives one
Propranolol REDUCES fear in this case
What leads to prediction errors?
When your knowledge is no longer predicting well enough or is outdated, it leads to prediction errors and your memory becomes plastic/it can be modified .
What are the two possible positions of retrieval or storage problems?
Nothing is really lost and real memory lost exists
What is the theory that nothing is really lost in the mind?
Everything we learn is permanently stored in the mind, although sometimes particular details are not accessible
With hypnosis, or other special techniques, these details can be recovered
CANNOT DISPROVE THIS
What is the theory that real memory lost does exist in the mind?
Some details that we learn may be permanently lost from memory. Such details would never be able to be recovered by hypnosis, or any other special techniques, because the details are simply no longer there.
Describe how one of the operations of memory is forgetting.
Ribot – Forgetfulness, except in certain cases, is not a disease of memory, but a condition of health and life.
Forgetting is as important of a function as remembering. If we remembered everything, we should on most occasions be as well off as if we remembered nothing.
William James – Would take as long for us to recall a space of time as it took the original time to elapse – we should never get ahead with our thinking.
Estimate the memory duration when participants look at how many letters they can remember.
Duration of iconic memory is about 500ms
Estimate the memory duration when participants look at specific rows they were told to look at and need to recall those letters.
Partial report technique – memory lasts so much more than 500ms, what you forget is where they were on the screen.
What is the Short-term memory – Brown-Peterson Distracter task and what were the findings of this task
Based on the idea that in order to measure duration of information in STM, rehearsal has to be prevented because continuous rehearsal keeps information in STM.
- Present participants with non-sense syllables and ask them to remember it
- Ask participant to count backwards in threes from a random number
- Ask participant to recall nonsense syllable
*Found that STM stops at 18 seconds and that the more times participant did the task, the worst they did because the previous material learnt messed with the task at hand
What did Da Vinci do in regards of episodic memory?
He tested himself for episodic memory accuracy and found that he could forget about them easliy
What are flashbulb memories?
Memories from circumstances as public event; as if there was a photo memory. Ex. 9/11, death of Diana…
These memories are not about the events themselves but about the reception event, in which one hears about a public event
How well do people remember flashbulb memories after a year.
One year after flashbulb memory occurs, people also tend to forget things that they are CONFIDENT they remember and say the same thing they said last year was the same.
What is the forgetting curve – Ebbinghaus
Tested himself over the years
Forgetting rates of most episodic long-term memories
Exponential decrease (R=e^(-t/s))
What are the main reasons for forgetting?
- Erasure/storage failure. True loss of memory content (consolidation impairment)
- Retrieval failure. Memory exists but cannot be expressed
- Memory disruption. Memory is smeared or broken up (interference, trace decay)
What is interference in memory?
The new learnings overwrite the existing memories
What is decay in memory?
Memory weakens over time and is eventually lost
What is Thorndike’s theory of disuse?
When you don’t use a memory that you learned, the connection strength decreases
This was rejected – no mechanism – interference is a better explanation
Passive-trace decay (No such thing as active-trace decay)
What is the new theory of disuse?
Storage strength - Indicates how well an item was learned
Retrieval strength - Indicates how well an item can currently be accessed
The theory assumes that storage strength will not be reduced and that no item will actually ever be lost from memory
Retrieval strength however, changes over time
Over time, old memories can becomes less accessible because they are retrieved less often, as newer, more relevant memories replace them. This confirms that when memories are formed, we change the synapses
How do the synapses change during the new theory of disuse?
During learning – signal being sent to synapses making memory
The synapses change and now have more AMPAR receptors that makes the connection stronger
Erasing memory is the removing of receptors and memory is put here
What would blocking AMPAR receptors achieve?
Blocking AMPAR receptors might block forgetting. This means that memory would be fine and remain the same in the brain.
What is Active Decay?
Built in process that removes memories over time
A forgetting process that actively removes AMPAR receptors. It requires activity/some form of signalling that this happens (telling synapses to remove AMPAR receptors)
This serves a purpose, if you forget details; it allows you to generalize
What is Endogenous?
A forgetting process that systematically erases memories
Brain has built in forgetting processes that kind of reverses whatever learning and memory did to connections in synapses.
What is proactive interference?
Old memories proactively interferes with new memories
Ex. New phone number that you cannot remember because you automatically remember your old one
Hard to reproduce
What is retroactive interference?
New memories retroactively interfere with old memories
Ex. Forget the name of the first person you met at the party because you met five other people after that
What is forgetting as a retrieval error?
The existence of forgetting has never been proved – we only know that some things do not come to our mind when we want them to
Availability vs. Accessibility
A memory can be available or unavailable. Information is available – stored somewhere in the brain – but temporarily or permanently inaccessible - cannot be retrieved. Info is still in the brain – maybe inaccessible but it is still there.
What is the encoding specificity principle ?
The higher the overlap between encoding and retrieval. The better the memory
Context is being apart from this memory
Everything around you is incorporated into context.
What is Transfer appropriate processing
If the processes that are engaged to encode an item are appropriate for the retrieval task to be used to recall the item, memory performance will benefit
If you encode a word by processing on what rhymes, it will be easier retrieved in a recall task that asks you to make rhyming judgements
How was the relationship between encoding processes and recall processes proven?
Study Task: Participants were read 32 sentences. In this sentence, a word was missing.
Then, after 2 seconds, they were given the missing word, which either made sense (Yes Target) or not (No Target).
Semantic Processing Study Task: “The _____ had a silver engine”
Target Word: train
Phonetic Processing Study Task: “____ rhymes with regal”
Target Word: eagle
Test Task: Immediately after study task, participants were given recognition test consisting of 64 items (32 targets and 32 foils)
Standard Recognition (more semantic)
Participants had to say whether they recognize the word as a target word (Yes/No Recognition Test).
Rhyming Recognition (more phonetic):
Participants were given words that rhymed with the original targets (or not) and had to say whether they recognize it rhyming with a target
