the remembering brain - part 2

Question 1

What is STM?

Answer 1

memory for info currently ‘in mind’ - limited capacity

Question 2

What is LTM?

Answer 2

stored info that need don’t need to be presently accessed or consciously accessible
unlimited capacity

Question 3

When is info in the LMT and when is it in the STM?

Answer 3

all info from minutes, hours, days ago in LTM
information which is presently brought to mind (cued) is moved from the LTM to the STM to be accessed. It is then (re)consolidated and stored

Question 4

How does WM and STM differ?

Answer 4

STM - passive store used for maintenance
WM - info currently being manipulated, used for higher processes and various complex functions

Question 5

What functions are supported by the WM?

Answer 5

active manipulation of info for high cognitive functions e.g reading
underlies execution of complex behaviour regardless of cognitive domains which are being engaged

Question 6

What happens when WM fails?

Answer 6

the ability to carry out daily activities is impaired

Question 7

How does working memory support complex activities e.g social situations?

Answer 7

Gathers sensory info from the environment
Retrieves schemas in LTM
This info stays active in WM and dictates how you behave

Question 8

Outline Baddeley and Hitch’s WMM

Answer 8

Separate STM sores and executive system for manipulating and controlling info in stores
Slave systems - visuospatial sketchpad, episodic buffer, phonological loop, controlled by central executive

Question 9

What is the episodic buffer?

Answer 9

Added later
Temporary store of info brought to mind from LTM when needed

Question 10

Outline alternative arguments to the WMM

Answer 10

argue against separate STM stores
instead working memory is activity in LTM

Question 11

Outline the structures of the phonological loop

Answer 11

Phonological store
Rehearsal mechanisms

Question 12

Outline evidence for the existence of the phonological store.

Answer 12

Paulesu PET study
-STM memory for letters- store and rehearsal components
-and rhyming of letters- rehearsal system only

Question 13

What are the neural correlates of the phonological loop? (Paulesu PET study)

Answer 13

Phonological loop = left supermarginal gyrus
Rehearsal system - Broca’s area (B44)

Question 14

Outline Ranganath’s study into the visuospatial sketchpad.

Answer 14

 Study by Ranganath et al., (2004) explored visual WM maintenance and long-term associative retrieval
 Prescan – ppt shown either a face, a building, or a face and a building together
 C1 – delayed matching to sample
* Aimed to test WM
* Ppt shown face or building , then 7s delay, then shown a face/building, had to say if it was a ‘match’ or ‘no match’ to the original face
 C2 – delayed pairs associate
* Control aimed to test LTM
* Ppt shown a building, then 7s delay, then a face, had to say if it was a ‘match’ or ‘no match’ to the pair in the prescan

Question 15

What were the results of Ranganath’s study into the visuospatial sketchpad?

Answer 15

Results for DMS trails
* Fusiform Face Area (face sensitive) activated on face trials
* Parahippocampal place area (place sensitive) activate on building trials
* Even in delay, activity in these areas remained above baseline activity = retain the knowledge/ maintaining single object in STM involves activating ventral stream representations
* Good performance on these tasks - frontal and parietal lobes activated during the delay period = these regions are functionally connected to frontal and parietal regions and involved in WM

Question 16

What evidence is there for the connection between the WMM and the prefrontal cortex? How are these results interpreted?

Answer 16

Gazzinga
delayed response task in animal studies
animals had to retain location of unseen food during delayed period (working memory)
prefrontal lesions affect ability in performing this task
BUT - performance could be due to deficits in long term associative memory instead of WMM

Question 17

How did Gazzinga test working memory vs associative memory for delayed responses on animals

Answer 17

To address - How do we know this is due to WM and not just very rapid associations being formed in the LTM about food and location?
 A similar paradigm used to test associative memory
 Food is paired with a visual cue (e.g a plus sign)
 Measures ability to retain LT rules, and does not measure WM at all
 During delay period, monkey doesn’t need to retain any visuospatial information (like WM) but merely the rule
 PFC damage doesn’t impair ability to do this task – WM component (represented by PFC) is therefore separate

Question 18

Outline an animal study which establishes PFC neurons contributing to maintaining information in WM

Answer 18

animal study:
- PFC neurons differential respond to different stages of the experiment (cue, delay, response)
- neurons active in delay provice neural correlate for keeping representation active after a triggering period is no longer active after response
- indicates neurons in PFC involved in keeping representation active in WMM/VSS during delay

Question 19

when do PFC become active again to a response

Answer 19

remain active if animal needs to use info for forthcoming action
-if task conditions change, same neurones become responsive to new set of stimuli

Question 20

what is the role of the PFC

Answer 20

activity represents the need to accomplish a specific goal rather than representing a specific item

Question 21

what evidence is there for the goal-oriented role of the PFC?

Answer 21

Druzgal & Desposito
-PFC working memory for faces
-task to match faces
-PFC sustained activity across encoding delay and retrieval periods
-significantly more activity in PFC when more faces needed to remember
-indicates specific face is not represented, instead activity is for goal

Question 22

how was the prefrontal cortex activity different to fusiform face area in Druzgal & Desposito’s study? what conclusions were drawn?

Answer 22

-FFA activity steep decrease during delay
-prefrontal cortex activity was consistent
-indicates FFA for specific representations of items
-prefrontal cortex for goal
The prefrontal cortex is important to sustain activity when we have to retain things in our mind without being specific to stimuli

Question 23

What interaction does WM rely on?

Answer 23

interaction between PFC and other parts of the brain that contain perceptual and long term knowledge relevant to a goal

Question 24

What does PFC activation represent?

Answer 24

-prefrontal cortex activation reflects representation of task goal

Question 25

What is Petrides’ theory of WM?

Answer 25

assumes division of PFC into at least 2 separate processes
-maintenance and manipulation

Question 26

Where does maintenance and manipulation occur in PFC?

Answer 26

ventrolateral PFC - retrieves info from LTM stores and maintains it in order to accomplish a task

doroslateral prefrontal cortex - uses info from VLPFC
manipulates and monitors info depending on task demands
(ev from self-ordered pointing task)

Question 27

What areas of the PFC are involved in encoding?

Answer 27

-lateralised responses in PFC at encoding depend on the type of materials
-encoding of words or semantic materials involve left PFC
-encoding of spatial info or faces involve right PFC

Question 28

How does the PFC have a role in LTM?

Answer 28

-role in memory encoding
-activation of PFC and hippocampus signals successful encoding of information

Question 29

How does the PFC have a role in retrieval?

Answer 29

PFC regions aid in organisation, selection, monitoring and evaluation of processing what occurs at retrieval

Question 30

what evidence is there for the role of PFC in retrieval?

Answer 30

-during free recall
-increased activity in DLPFC with increased demands
-as more need for monitoring in retrieval

Question 31

what sort of retrieval causes most activity in dorsalateral PFC?

Answer 31

-free recall as info requires more manipulation and monitoring as there are minimal cues
-eg more than recognition
-PFC damage results in more impaired free recall than recognition memory

Question 32

what is source monitoring?

Answer 32

related to recall and recollection that stresses the ability to attribute retrieved memories to their original context

Question 33

how is the PFC involved in source monitoring?

Answer 33

-involved as placing event in context requires active evaluation process before we are able to access the origin of memory

Question 34

how does damage in the PFC effect source monitoring?

Answer 34

-impairs putting memories in spatial and temporal context
-can recognise memories but fail to retrieve from correct source
-more likely to confabulate (report fabricated events)

Question 35

summary of roles of PFC in memory

Answer 35

-maintaining info in working memory
-selecting info in environment to focus on (important for encoding)
-providing cues and strategies to enable memory retrieval
-evaluating content of memories eg source monitoring