Brain Systems for Memory (The Remembering Brain) Flashcards
what type of deficit is amnesia?
specific memory
verbal behaviour can index what?
non-conscious memory (can prime via previous exposure to words, as the lexical have been activated)
why is memory important?
- critical for everything about cognition
- learning from experience shapes thought and behaviour in an adaptive way (so they are more adaptive)
- perception / attention
- underpins conscious and unconscious decisions
- central to personal identity
- allows language and culture (we share memories with one another - shared experiences create a shared culture and shared identity)
- practical importance of memory failures (i.e. they aid us in learning from our mistakes - and support independent living i.e. for those with Alzheimers)
perception
an interaction between sensory input and stored knowledge
attention
driven by memory (i.e. cocktail party effect - change of attention based on the importance of someone else’s statement / attention is guided by semantic information
who is Clive Wearing?
- conductor and musicologist who developed dense amnesia in 1985 following encephalitis
- STM -> can retain about 20 seconds
- capacity to play piano not affected by his brain trauma
- his language, knowledge of general information and speech fluency is preserved (semantic knowledge intact)
- can retain sentences when he’s processing and then everything else is void
- he has some understanding in which he has a brain injury
Who is Patient HM (Henry Molaison)
- bilateral medial temporal (lesion) lobectomy to treat epilepsy in 1953
- removed hippocampus in both hemispheres
- epilepsy cured but unexpected consequences for memory
- virtually all anterior hippocampus and surrounding cortex removed, plus amygdala
- some posterior hippocampus remains
what were some issues with HM? Like when we assessed his memory problems what happened?
- no memory for things that happened since operation -> dense anterograde amnesia
- some forgetting of events that happened 11 years before surgery (yet childhood memories preserved) -> retrograde amnesia
where does the hippocampus lie?
temporal lobe
where does hippocampus lobe lie?
all the way from the anterior to the posterior
-> right next door to the amygdala
what is the hippocampus output bundle called and what does it do?
fornix -> projects to the millimary body -> sends information via the thalamus back to the cortex in a loop
how did know HM had dense anterograde amnesia
Read the same magazines; watched the same movies; did the same jigsaws repeatedly; ate lunch several times in a row; unable to learn his way around the hospital
anterograde amnesia
affecting memories that are affected since the brain injury
retrograde amnesia
affects memories formed before the brain injuries take place
why was retrograde amnesia not complete?
could still remember childhood memories and they were preserved
what does HM suggest about the hippocampus?
crucial for new learning and for storing recently-formed memories but not for older memories i.e. childhood memories
what happened as HM aged?
his rooting of time/age got more and more inaccurate
what was HM’s amnesia caused by?
surgical resection of hippocampus -> very specific
what are some other causes of amnesia that also produces damage to bilateral medial temporal lobe
- Anoxia (e.g., heart attack; carbon monoxide poisoning) [hippocampus] -> lack of oxygen reaching the brain
- Patient RB – anoxia following heart surgery [almost entirely in a specific cell field in the hippocampus] (Zola Morgan et al., 1986)
- Head injury [hippocampus, thalamus, frontal lobes]
- Patient KC (Rosenbaum et al., 2005)
- Herpes simplex encephalitis [hippocampus and anterior temporal cortex]
- Clive Wearing, Patient EP (Insausti et al., 2013)
- Korsakoff’s syndrome [mammillary bodies] - Vitamin B deficiency
- [Alzheimer’s disease]
why can patients with amnesia vary?
some injuries are not as specific -> so they cause damage to other structures
* patients with amnesia show a variety of different symptoms dependent on what is damaged
Where is the Hippocampus
within medial temporal lobe
Fornix
major output bundle of hippocampus
Mammillary bodies
gateway from hippocampus (fornix) to thalamus (and then back to the cortex- but mammillary bodies do’t do this)
Thalamus
receives and feeds back to the cortex
-> in a corticothalamic loop (pass info between the thalamus and the cortex
Episodic Memory
Event Memory
Semantic Memory
Factual, Conceptual Knowledge
what can we argue about different types of memory
they use different brain systems
STM
short information in your mind
-> if you keep thinking about it - you can keep it in your head (rehearsal) and people with amnesia can do that (STM is preserved)
Procedural Memory
Skills that you learn
what memory is affected in amnesia?
episodic memory
people with hippocampal amnesia, have problems with verbal learning. What does this mean?
Learn Chair-Cat
* asked after a delay of several minutes to retrieve the section word
-> task only works with someone who has mild amnesia (assess how severe the impairment was) but won’t work with patient EP because that simply wouldn’t remember studying any word
Can patients with do visual learning tasks like the key figure copy with amnesia?
can copy it out while in front of them -> showing us they have good control of their hands / eye sight etc. allowing them to control the figure accurately
- after a 15 minute delay, individuals with amnesia will have issues with reconstruct what they saw (good for mild patients to test how severe the impairment is)
Why can’t those with severe amnesia do verbal or visual tasks?
because they’ll never even remember learning the word or copying the figure
why are those with Alzheimer’s bad at Rey Figure Task?
issues with coordinating space
what is preserved in amnesia?
STM
what is the normal ability to short-term memory
holding onto information actively for a few seconds (short-term working memory)
how do we know that HM STM was intact?
could remember the number 584 for 15 minutes by continuously rehearsing it
-> number was lost after only a brief distraction
how do we know patient EP STM was intact?
could repeat the list of four names without difficulty
what can we conclude from STM memory being intact?
amnesia patients are only impaired when information must be retrieved after a period of not thinking about it
why does amnesia have preserved STM?
Hippocampus (damaged site) is NOT crucial for using attention to keep information active
what other type of memory is preserved in amnesia?
semantic information / memory
* normal retention of factual information
how do we know semantic memory is preserved in amnesia?
normal performance on tests such as providing definitions, naming pictures and understanding sentences
what can we conclude from semantic memory?
hippocampus is not final store of knowledge
How can we understand that classical condition is preserved in amnesia
Claparède (1911): Handshake with concealed pin; later patient refuses to shake hands despite no recollection of doctor
Non-conscious memory made
-> classical conditioning made her not want to shake the doctors hand
what is classical conditioning an example of?
implicit (non-conscious) memory
what research suggests that motor learning is preserved?
Milner 1968: Mirror drawing in HM (Procedural Memory) - counted how many times the pencil came off the line (as errors)
* asked him to do it 10 times a day, for 3 days in a row
- found a very rapid learning curve
- His performance improves significant and by the beginning of day 2, he’s retained information on how to do this task without any recollection of how to do this, but with training and learning, he is able to do it - yet having no memory of having done it before -> he’s retained memory about how to do this task without actually knowing he’s ever done it before
motor learning is an example of..
implicit memory
what does motor learning tell us about memory?
Hippocampus not required for some unconscious motor skilled learning
what does priming suggest (Graf et al. (1984))
- present words and at the test phase were asked to try to complete the stem of the word with the word they had remembered earlier (condition 1) or any word that came to mind in (condition 2)
- in a priming situation - you tend to say the word you were previously presented with
- controls in group complete stem less often when they’re not explicitly told to repeat it
patients with amnesia will only be impaired if it’s an explicit memory task - but not an implicit task (even though it’s the same words)
priming is an example of?
implicit memory
what do priming studies suggest?
Impaired and intact memory for same information depending on requirement for conscious retrieval.
-> you only see an impairment if there’s a requirement for conscious recollection
what does memory split down into?
STM (working memory) and LTM
LTM splits into
declarative/explicit (conscious awareness) and non-declarative/implicit
declarative / explicit
episodic and semantic
non-declarative / implicit
procedural, priming (i.e. fragment completion) and classical conditions
what memory is impaired from hippocampal damage
verbal and visual stimuli
-> suggesting hippocampus stores multimodal experiences
what memory is preserved in hippocampal damage?
- ability to retain information in STM
- retrieval of OlD information - semantic knowledge and childhood events
- motor learning, perceptual priming and other implicit memories
-> hippocampus not crucial for registration or rehearsal of information
-> hippocampus does not underpin all LTM storage
-> hippocampus not crucial for all types of learning
what is the hippocampus crucial for?
conscious retrieval of an experience or episode
-> mental time-travel made possible by binding together different experience aspects
how do we bind together different experiences?
familiar character in anterior temporal lobe, object in inferior temporal cortex and place in the parahippocampal place area bind together in the hippocampus to create a memory / representation bind elements of experience into one experience
-> representations of all elements of memory
so next time, the object will reactivate the hippocampus and send signals to the other cortical representations, reactivating the items to recollect the memory
Horner et al. (2015) fMRI study. what did they find?
location, people and objects activate different brain regions
-> distinct patterns of activation for place, people and objects in encoding
retrieval: same distinct areas show reinstatement of non-presented places, people and objects
hippocampal activation at encoding predicts later memory, and activation at retrieval predicts ‘reinstatement effect’
-> hippocampus allows you to recollect something as a complete whole
when does retrieval occur
spontaneously from one of the elements (cue) when links are strong; this reinstates activity in cortical areas active at encoding
-> explains why memories are often unbidden (activated by cue) and why forgetting is often a problem (when cues are weak)
What is dense amnesia?
Remembering almost nothing about ongoing events later
The hippocampus is in the medial temporal lobe. What does ‘medial’ mean?
Deep inside the temporal lobe
Why is HM an important case study?
He was the first close-studied hippocampal amnesic and his brain injury was largely restricted to the bilateral hippocampus
What is retrograde amnesia?
Difficulty remembering events from the period leading up to the brain injury
What is the output fibre bundle from the hippocampus called?
Fornix
How do we know the hippocampus binds elements of memory?
Reinstatement affects in fMRI
Which makes minimal demands on short-term memory?
Remembering the names of your friends
Which would be an episodic memory?
Thinking about a picnic you went on last summer and recalling the world a psychologist ask you to remember
Which is semantic memory?
Remembering badgers are black and white
