long term memory complete Flashcards
what is semantic knowledge
general world knowledge that humans have accumulated throughout their life
2 basic facts about memory and the NS
in order for there to be a memory, there has to be a physical change in the NS
diff parts of brain are responsible for diff types of memory, nonetheless, memory is quite pervasive in the nervous system, hard to find a part of the NS that doesn’t have some capacity for learning and memory
we make an alaogy of memory to computer systems because both share an
common underlying representation, in the case of memories in the NS, that representation is in the connections between neurons , and how strong those connections are
___ maintenance for short term memory
______ storage for long term memories
Active maintenance for short term memory
Passive storage for long term memories
3 differences between computers and our brains in this analogy
parts of machines that store memories are physically distinct from the parts that do the actual work (processing) hard drives vs central processing unit for example - NOT how the NS works,
in a computer you can have a pattern of 1s and 0s and copy it from place to place easily through cloud email etc, same pattern means the same thing, in the brain you can’t move memories around in the same way, the meaning of a memory, as encoded by connections between neurons is fundamentally tied to which neurons we are talking about,
In a computer primary way memories are accessed is based on their location - you look info up by specific physical location on a chip or disc, in Human Memory - accessed based on a cue - based on its content
4 processes required for memory to work
Encoding - has to be encoded into the brian in a way that can be put into memory
Consolidation - initial coding often changes over time if we keep a memory around
Storage - at some point the memory is stored, hopefully sticks around
Retrieval - accessing info from stored information traced
Reconsolidation - possible reorganization of memory traces after retrieval. Can get rewritten from retrieving it,
how do we use dissociation to look at the extent to which one system or the other can be damaged
If you are able to show damage to one part of the brain is associated with one process, damage to another part is associated to a diff process - gives you evidence that they are 2 different systems
memory span tasks test _____
short term memory
list learning task test ____
long term memory
how does the memory span task work
you have a sequence of words and the example here is 3 words - time, base, offer. Your job is to try to recite them back in the same order as accurately as you can. Number of words cna differ but that is the basics of the task - immediate recall in correct order
how does the list learning task work
you hear a longer sequence of words (10) and then you are to recall them and it can be in ANY ORDER, if you don’t get them all right you get to hear them all again, try to recite them again, do it until you can recite the whole list correctly
what is a single dissociation
a patient who is impaired on one task but not all, is a Single Dissociation
explain the partial damage argument for dissociations
maybe there is only one system being used to perform BOTH tasks, and maybe this patient has partial damage to that system - because the short term memory task is Harder than the long term one the partial damage has led to a drop in performance on the harder tasks - but is intact enough to complete the easier one
explains the single diss without saying there must be 2 distinct brain systems
explain the compensation argument for single dissociations
maybe the damage knocked out a single system that would normally be used for both tasks - but because the short term task is harder, the participant has found a way to compensate for the easier task but not for the harder one
what brain damage did HM have
temporal lobes bilaterally
what gives us the Double Dissociation
This crossover pattern with 2 patients with damage to 2 distinct brain areas with opposite patterns of impairment on 2 tasks gives us our
short term vs long term mmeory - which has more capacity
Short term memory is extremely LIMITED (7 words in task)
wheres LT is massive in comparison (20000 words in vocab)
short and long term memory are represented in different ways
LT memory seems to be based on the strength of connections between neurons as well as NUMBER of connects
ST is represented by WHICH neurons are currently active in the brain - sometimes neurons can maintain that activity for at least a few seconds
different physical bases in the brain for these two - current activity VS structural connections
what is the perceptual identification task and what type of memory is it used to test
used for implicit memory
study phase - words are flashed on a screen for 2 secs each, one after the other -
test - identify the word as fast as you can - some you have seen before some are new - is it easier to ID the ones you have seen before
what memory type was the word recognition task test
Explicit
study phase you see 24 words flashed for 2 seconds each
test phase - you are again get a mix of old and new words at random, each word appears on screen and stays as long as you need in order to respond yes it was in first phase or no it is a new word - here you are explicitly asked if they are new words or if you already saw them.
how does the MS patient do in the explicit word recognition task and the implicit perceptual identification task
Now by comparison you can look at the performance of MS patient (damage to right occipital lobe) they do NOT show a priming effect in perceptual id task they are impaired, BUT they are able to Explicitly recall the words as well as the control group
they have a Single Dissociation between Implicit and Explicit Memory
not neough to prove anything
how do the amnesia patients do on the explicit word recogniton task
they are impaired on the explicit word recognition task, but show a priming effect if anything larger effect as it helps them more
how is the double dissociation shown in the implicit and explicit tasks
we put the MS patient and the Amnesia patient together - they both have damage to different places - strong evidence that implicit and explicit memory are distinct processes that depend on diff parts of the brain
explicit memory
declarative, things we can remembr and bring to mind
the two kinds of non assocaitive memory are
habituation and sensitization
describe habituation
response decreasing with repetiton
hearing the fan until you get used to it
describe sensitization
response to unchanging stimulus repeated becomes increased over time
someone rubs your hand and it starts to hurt
what does sensitization involve - pathway
sensory motor reflex pathways
what is presynaptic depression
the neural basis behind Habituation
sensory neuron fires the same AP every time it is touched, releases less NT over time causing the EPSP goes down if the presynaptic motor neuron becuase less receptors take up the NT
presynaptic facilitation
neural basis of sensitization
AP of sensory neuron stays the same, but over time it releases MORE neurotransmitters, causing the EPSP in the motor neuron to increase
what are the long term effects of habituation and sensitization
an increase or decrease betwen the sensory and motor neurons
in pavlov’s dog
what is the unconditioned stim
the unconditioned response
the conditioned stim
the conditioned response
US - food
UR - salivation
CS - bell
CR - salivation
descirbe the rat fear cond study on simple terms
If you play a tone for the mouse it doesn’t have a response at first, on other hand if you give the animal a light shock to its feet done through the surface of the cage, the animal will freeze in response. The shock is the uncon stim, and freezes is uncon response. If we now pair tone and shock together and then test the animal again by tone by itself, we find the animal freezes in response to tone.
for the fear cond rat study, we have audio stimulus and somatosensory stimulus - where do they converge
tone and shock converge on the Lateral Nucleus of Amygdala - as this area is critical for fear conditioning
in the rat study looking at fear cond, why are EPSPs represented by a dip in the curve
because they are measured form outside neurons, if neuron has positive effect then + ions flow into the neurons to create the EPSP, and the outside becomes more negative
what response does the lateral nucelus of amygdala to the tone when it is paired with a shock vs not paired
same tone played, same AP’s in incoming sensory cells, but leads to different effects on the cells in the LN of Amygdala that create larger EPSP’s in response after pairing the tone with the shock
in the rat tone shock study - where does the fear conditioning occur
in the lateral nucleus of the amygdala
there are two kinds of implicit/procedural memory
what are they - and what part of the brain are they involved in
Motor Adaption - depends on cerebellum
Sequence Learning - involves CorticioBasalGangliaThalamicCocortica Loops
what study reflects motor adaptation in the CB
what is this process called
dart study
person hits dart
puts on prism glasses - misses dart
learns to compensate and hits dart
removes glasses - misses dart
compensates to reality - hits dart
Adaptation
what would someone with a damaged CB do in the dart study
what does this suggest
hit dart
put on glasses - miss dart
don’t adapt to glasses
remove glasses - hits dart
doesn’t take time for them to adjust to reality because they never adapted to the glasses
suggests profound lack of motor adaptation in absense of a functioning CB - no feedback loop that corrects them
describe the study that shows how motor sequence learning works
participant with a set of buttons, when you see a light you push matching button fast
get a sequence of them
if you get the same sequence twice, you can do it faster, even if you don’t recognize that you have done this sequence before
how do you know what actions to take and when
BG loops are trained via reinforcement learning
positive and negative prediction errors
believed to be controlled by Dopamine from substantia nigra - burst of it strenghthens direct pathway, and inhibits indirect pathway
how does dopamine have diff effects on the two pathways
Dopamine from substantia nigra - burst of it strengthens direct pathway, and inhibits indirect pathway
possible because each has receptors that react differently to dopamine
what is priming
situations where being exposed to a stimulus leads you to later think about either that same stimulus or something similar even without being aware of that priming. Can take a few different forms.
3 diff kinds of priming
conceptual - meaning of the word
semantic - words of related meanings
perceptual - gollin photos that show the whole picture gradually, amnesia patients
conceptual priming
based on MEANING on the word -
Primed with a word envelope, now
going to present dif words to you and you have to think of related words.
He says cue is stationary - what words are related - you find you are more likely to think of envelope
semantic priming
Primed with word envelope but now imagine that a bit later you are doing a task where you list words starting with S.
you say stationing, it comes to mind faster having recently seen an envelope than if you hadn’t recently seen an envelope.
Here the thing that is coming to mind is not the exact word that was primed but another word related in meaning.
Think of it like if you are primed with something it activates not only the word envelope itself, but also primes other related words like paper, letter, or note.
perceptual priming
gollin pictures - start w fragments and have to guess what the photo is
do this amnesia patients
come back the next day and they can tell faster what it is even though they don’t remember doing it before
describe the semantic priming task
similar to lexical task
given a prime, then delay, then a sequence of letters - have to say if htey create a word or not
in one trail the word is related to the target, in others not.
people could say faster if it is a word or not based on if it iwas related to the target
seeing the word primes you of related words as well
where does priming happen in the brain
Cortex
perceptual priming involves sensory as well
but the rest are higher up in areas that deal with semantics and categories
- anterior temporal, inferior parietal, prefrontal cortex etc
where in the brain is semantic memory
name to the theoriies
Sensory Functional Theory - in the cortex, organized by sensory functional features of words
- words based on sensory, visual, auditory features and motor features bell - audio, kick in motor area of legs, pick motor arm area,
Domain Specific Theory - based on semantic categories - one area for fruits, one for veggies,
how can we reconcile these two diff theories of cortex organization
domain specific vs sensory functional
data for both - activations are categorical, but they also sensory functional in organization because item sin categories tend to be correlated in their sensory and functional features (tool and actions, animals and how they look
likely to some extend that both of these theories have some truth to them
how do we end of with semantic memories - representations of meaning
we learn about world through episodic memory - after what we learn is ingrained well enough - the information becomes semantic, and we can’t remember the episodic memory of learning it
the encoding of episodic memory depends on 2 brain structures, has 2 key aspects to it - describe the process
HippoCampus & Medial Temporal Lobes (glue)
the ind. representations of the halloween party - sam, elmo - have prior experience with them
Hippo - binds ind representations together into a specific epi memory of the event
retrieval of episodic memory - halloween party
a friend says remember the party? mentions sam and elmo, causing the representations for those to be activated in our semantic representations in Cortex
also functions as cue for the HC binding to come active too
sam and cue = cues for whole memory to come back
describe the movement of semantic representation via cortex. mtl, HC
semantic representation in the cortex - unimodal and polymodal association areas
when they become active they are fed down into the MTL - via Perihinal and ParaHippoCampal Cortices
and into the HC via Entorhinal Cortex
Entorhinal is a pathway into HC proper
Semantic Representations have flown into HC through the following steps, but we need a way for into to get back out so the HC reps can activate cortical representation
what does the fornix do
grey or white matter
main output pathway that connects both side of HC together and also connects HC up to other parts of the brain
a white matter tract
spatial role of medial temporal lobes and the study where they discovered it
theory of this is called, cells active in this are called….
Cognitive Map Theory
rat in maze, track where it is, while recording ind neurons in MTL - keep track of when they fire and create map of where animal was each time it does
see these cells MTL is active based on where the animal is - so theyre named ‘Place Cells’
besides the cognitive map theory - what else did they learn the MTL can do via what kind of study?
Relational Memory Theory of MTL
Odour associatioin task - animal has to pair diff odours over each other following a general rule they have to apply to diff situations
One can do it well, the other group has Lesioned Fornix - their primary output pathway from HC and MTL is disrupted, so they can do the basic task, but not when they relate it to a more complicated situation
proves there is a General Associational Component of MTL as well as spatial - the relational memory theory
what does the Perihinal Cortex do
feeds the ‘system’ of MTL,
specialized for representing the bindings between features that form objects (colour, shape, taste of fruit) - object coding
what does the ParaHippoCampal Cortex do
similar to perihinal but focused on representations of where things are relative in space - banana and grape on a fruit plate - spatial coding
both the feature data from perirhnial c and the spatial data from parahippo cortex are fed into the
hippocampus that binds all these aspects together into the overall memory
neurons that fire together wire together - is the jist of what kind of learning
Hebbian
hebbian learning in neurons - overview
presyn neuron fires resulting in post nueron fires - strengh of that synpatic connection is increased - next time presyn fires it is more likely postsyn will too
what mechanism in the brain implements the process of hebbian learning
what two terms C and A are related to this principle
if all 3 neurons fire and collectively cause an AP in the output - we get LTP and Connectivity
image one of them has previous connection and it firing alone is enoguh to cause AP, but it happens that the 2nd neuron fires AP at the same time - but its just along for the ride - we get Associativity
if 1 and 3 fire and 2 dont - LTP only occurs at the synapses that were involved in generating the AP
early ltp and late ltp
early - strengh of exising synapses created by increase of NT release and number of functional receptors on other side
late - increase in number of synapses between the two neurons
if presynaptic neuron fires an post one doesn,t there is a weakening of connection between the 2 neurons - what is this called - what are the 2 phases
long term depression
early - reduction in amount of NT released and less functioning receptors on other side
late - fewer synapses between the two over time
helps stop runaway lop of positive feedback
reconstruction refers to __ in waht kind of memory
when we think about episodic memories we often change the memory based on current goals and thought
study that shows reconstruction
memroize list of words related to sleep
see words after and try to say yes or no if they were on the list or not - one of them is related to sleep, but not on the list but since its related we say yes and feel confident it was part of the original list - lure words
list 5 reasons for error in reconstruction
Semantic Relatedness - why the sleep one makes sense
Past Cultural Experiences - remember things in a way consistent to what usually happens in our day to day life
Source MisAttributions - say a friend tells us something we missed during an event, later on we may think we saw it ourselves
Pragmatic Inferences - see a work shop, later someone asks if we saw a hammer we say yes cause that would be likely
Misleading PostEvent Info - given info after an event can influence our memory
how does Consolidation work
forming a new epi memory requires HC and Cortex (ind reps)
over time due to revisitn gmemory, sleep, gradually links between diff portions of mem start to get formed in cortex itself - depends less on HC
how does consolidation process explain HM’s memory loss
his HC was removed - so recently formed mems not yet consolidated were lost, childhood ones consolidated were not
no HC - couldn’t form any new memories
describe complementary learning systems hypothesis - why have both the HC and Cortical System
HC - learn quickly from single event - distinct memories
Cortical - learning generalities over time from repeated events
animal wants to know where to fruit tree is HC, also wants to know what a fruit tree is, what fruit to eat etc Cortex
both are important
do childhood events become semantic?
yes if you here them enough they are more like general knowledge of what happened and less clear memories of the event - grandpa telling story example
starts as episodic, through repetitioin becomes a more semantic cortical memory - less of a first person memory tied to a time or place
grey area here
is consolidation permanent
no because retireval makes a memory flexibe to be rewritten - inference or loss
rat study shown of reconsolidation
why did this work
day 1 - pair rat w tone and shock and it freezes
day 2 - play tone, no shock, rat freezes, inject memory block drug
day 3 - play tone and rat doesn’t freeze -
why? memory was retrieved on day 2 and wasn’t reconsolidated so the memory was lost
memroy is rewritten all the time
