Remembering the brain II Flashcards
What does the PFC stand for?
Prefrontal cortex
What does the DLPFC stand for?
Dorsolateral prefrontal cortex
What does the VLPFC stand for?
Ventrolateral prefrontal cortex
What is long term memory divided into?
Declarative memory (explicit memory) and nondeclarative memory (implicit memory)
What is declarative memory divided into?
Episodic memory (events) and semantic memory (facts)
What is nondeclarative memory divided into?
- procedural memory
- perceptual representation system
- classical conditioning
- non-associative learning
What is procedural memory?
skills (motor and cognitive)
What is perceptual representation system?
Perceptual priming
What is classical conditioning?
Conditioned responses between two stimuli
What is non-associative learning?
Habituation, sensitisation
Does the short term or long term memory have limited capacity?
Short term
Which memory system is information from minutes, hours days and years ago in?
Long term memory
When does information go from long term memory to short term memory?
When it is presently bought to mind
Why was the term working memory proposed?
It captures the idea that the information currently in mind is manipulated
What do we refer to working memory to denote?
the active manipulation of information within a STM store in the service of high cognitive functions (e.g. comprehension, reading etc)
What does short term memory stress?
The memory store itself
What id Baddeley’s (2000) model of working memory)
There are separate STM stores (visuospatial sketchpad, episodic buffer and phonological loop) and an executive system (central executive) for manipulating and controlling information within the stores
What is the capacity limit of the phonological STM assessed by?
span tasks (digit span, operation span)
Where does the phonological store lie?
Posterially in the parietal lobes
What is the central executive responsible for?
Refreshing information in the stores (rehearsal) and manipulating that information (e.g. using the list of numbers in STM to perform calculations
What is the evidence for the independence of buffers in Baddely’s model?
When someone is asked to do two tasks that share the same buffer then the ability in one of the tasks is reduced (e.g. if someone is asked to hold in mind a few words and repeat ‘the the the’ they both use the phonological loop. Whereas, if two tasks require two separate buffers then the person can complete both tasks
In a PET study by smith et al (1996) what brain regions did they find were active for the verbal short term memory task and for the visual short term memory task?
- Verbal STM: left hemisphere
- Visuospatial STM: right hemisphere
What is an operation span task?
- Participants read and verify a simple math problem
- then read a word after the operation (e.g. truck)
- The participants recall the words
- Greater load with more intervening words and operations
What did Miller (1956) suggrest was the span of the phonological STM?
7 +/- 2
What does chunking rely on?
LTM and LTM-STM interactions
What did Cowan argue the span limit is around?
4
Is there evidence for the Baddeley model which suggests that the phonological loop contains and phonological store component and a rehearsal mechanism?
Yes
Where did Paulesu et al (1993) find that the phonological store component and the rehearsal area corresponded to in the brain?
- Phonological store: left supramarginal gyrus
- Rehearsal system: Brodmann’s area 44 (Broca’s area)
What is the slot model of visuospatial STM?
We have a small number of memory ‘slots’ each capable of storing a single visual object with fixed precision
What is the resource model?
There is no upper limit on the number of items sotes; instead the more items that are held in memory the less precisely each can be recalled
What evidence did Luck and Vogel (1997) demonstrate supporting the slot model?
- They used a brief display of arrays
- Ps retain information about only 4 colours or orientations in visual working memory at one time
- Retain both the colour and the orientation of 4 objects
- Therefore, visual STM capacity understood in terms of integrated objects rather than individual features
How many slots are thought to be in short term working memory?
About 4 slots, each slot filled with an object. Different features of different objects in the slots can be remembered
What evidence did Bays, Catalao & Hussain (2009) show for the resource model?
- Presented Ps with array followed by a short delay. Then probed Ps with cue about what colour was in particular box
- The more items that are held in memory, the less precisely each could be recalled
- Therefore, visual working memory consists of a common resource distributed dynamically across the visual scene with no need to invoke an upper limit on the number of objects represented
Who explored visual STM/ WM maintenance (and long term associative retrieval?
Ranganath et al., (2004)
What was Ranganaths visual STM/ WM maintenance (and long term associative retrieval) experiment and what did they find?
- DMS trials: participant has to maintain the face/ house in mind for 7 seconds. Then presented with face again which may or may not match
- DPA: presented with house that was associated with face. Then presented with face, had to say if it was the face that matched the house or not
- condition 1 probed visuospatial working memory
- condition 2 probed visuospatial associative recall/ long term visuospatial associative memory
- found that activity within selective regions of inferior temporal cortex reflected the type of information that was actively maintained during both the associative memory and working memory task
- sustained activation found during delay period showing that keeping information in WM even when not actively looking at it engages brain regions that represent this information
What does maintaining a single object in STM involve activating?
Ventral stream representations
Prefrontal lesions in monkeys affect their ability to do what?
Retain the location of unseen food during a delay period
Does PFC damage disrupt working memory or associative memory and how do we know?
Working memory: when food is paired with a visual cue the animal remembers where it is
What do PRC neurons active during the delay period provide?
A neural correlate for keeping a representation active after triggering a stimulus that is no longer active
- They remain active only if the animal needs to use the information for a forthcoming action
- If the task conditions change the same neurons become responsive to a new set of stimuli
What do most theorists and empirical evidence think that PFC activity reflects?
Representation for the task goal
What are the results of Druzgal and D’esposito (2003) study where Ps are instructed to only remember intact faces?
- BOLD response within the lateral prefrontal cortex began to rise with the onset of encoding period and this response was maintained even during the delay period, because participants had to retain information so they could perform retrieval task
- delay response was higher when participants had to remember more faces
- Greater peak activation in fusiform face area when faces shown on screen but lateral prefrontal cortex shows sustained activation during the delay period
- However, neither LPFC and FFA dropped to baseline during delay
- shows that PFC works together with inferior temporal cortex to sustain information that is relevant for achieving goal across delay period
What is Petrides theory of WM?
assumes division of PFC into at least two separate processes - maintenance and manipulation
What type of tasks are patients with PFC damage impaired at?
Tasks that require you to remember previous decisions in your WM
Where did a PET study show that the short term retention of spatial information was?
The ventrolateral prefrontal cortex
where did a PET study show that the retention of short term spatial information + updating new locations was
?
The dorsolateral PFC
What does Atkinson and Shiffrin’s modal model propose?
Different stores for STM and LTM
What is the strongest evidence that STM is separate from LTM?
Neuropsychological patients and behavioural (primacy and recency effects)
What memory did H.M have?
- inability to make new memories (cannot transfer information into LTM)
- but intact STM
What damage and impairment did patient K.F. have?
- Left parieto-occipital damage
- normal MTL, good long term learning
Small digit span (STM)
What are the unitary models of WM/ STM?
- working memory is just the temporary activation of long term memories
- capacity limitation explain by the more items there are in WM the more interference there is
What does Cowan’s WM model say?
Central executive is responsible for selective and activation LTM representations (goal relevant) to bring them into ‘focus of attention’
What is CogNeuro evidence consistent with in terms of working memory being the temporary activation of long term memories?
CogNeuro evidence is consistent with the idea that WM entails temporary activity in parts of the brain involved in LT storage
What is the functional role of the DLPFC?
manipulation and monitoring
What is the functional role of the VLPFC?
Maintenance of activated representations
According to Kelley et al., (1998) what are the lateralised responses in the PFC dependent on?
- the type of materials
- encoding of words or semantic materials (e.g. objects that can be verbalised involve the left PFC
- encoding of spatial information or faces involve the right PFC
According to Fletcher and Henson (2001) what results in DLPFC activity?
increased need for monitoring retrieval (e.g. free recall vs recognition, low confidence judgements)
Does PFC damage result in more severe impairment during free recall or recognition?
Free recall
Why does free recall have increased need for monitoring?
As it takes greater strategic search, organisation, selection and evaluation of retrieved information
Is the PFC involved in placing memories in context?
Yes - this requires active evaluation
What deficits do patients with PFC damage gave?
- putting memories in their spatial and temporal context
- subjectively may experience ‘remembering’ (e.g. they can perform a recognition task) but will fail to retrieve the correct source
- they are more likely to confabulate: report narratives that include false memories
