The Remembering Brain II, Week 12

Question 1

STM (Short-Term Memory):

Answer 1

Memory for information currently “in mind,” with limited capacity.
Information stays in STM unless brought to mind, then it enters STM.
Gives the impression of a static/passive store [maintenance].

Question 2

LTM (Long-Term Memory):

Answer 2

Stored information that doesn’t need to be presently accessed or consciously accessible.
Virtually unlimited capacity.
Contains information from minutes, hours, days, and years ago.

Question 3

Working Memory (WM):

Answer 3

Term proposed to capture the idea that information in mind is manipulated.
Involves active manipulation of information within STM for high cognitive functions.
Underlies successful execution of complex behavior.
WM failure affects daily activities.

Question 4

Baddeley’s Model of Working Memory (2000):

Answer 4

Separate STM stores and an executive system for manipulating and controlling information within the stores.
Other approaches argue against separate STM stores, suggesting that working memory is temporary activity within LTM.

Question 5

Functional Imaging Evidence for Verbal and Visuospatial STM Dissociation (Smith et al., 1996):

Answer 5

PET study showed distinct brain regions active in verbal and visuospatial STM tasks.
Verbal STM activated left hemisphere.
Visuospatial STM activated right hemisphere.

Question 6

Neural Correlates of Phonological Loop (Paulesu et al., 1993):

Answer 6

Phonological loop contains a phonological store (verbal stimuli) and a rehearsal mechanism.
Paulesu et al. provided evidence for separation of store and rehearsal components.
Phonological store located in the left supramarginal gyrus.
Rehearsal system located in Brodmann’s area 44 (Broca’s area).

Question 7

Neural Correlates of Visuospatial STM (Ranganath et al., 2004):

Answer 7

Explored visual WM maintenance and long-term associative retrieval.
Activity in category-selective regions of inferior temporal cortex reflected maintained information.
Maintaining a single object in STM involves activating ventral stream representations.
These regions functionally connect to frontal and parietal regions during the delay period.

Question 8

Working Memory and Prefrontal Cortex (PFC):

Evidence from animal studies (Delayed Response Task):

Answer 8

Delayed-Response task measures working memory in monkeys.
Monkeys need to retain the location of unseen food during the delay period (working memory).
Prefrontal lesions affect their performance on this task.
Are the animals failing due to a deficit in forming associations or working memory?

Question 9

Working Memory vs associative memory:

Answer 9

Similar paradigm used to test associative memory.
Food is paired with a visual cue (plus sign).
PFC damage disrupts a not b task.
Prefrontal neurons respond to different stages of the experiment (cue, delay, response).
Neurons active during the delay period provide a neural correlate for keeping a representation active after a triggering stimulus is no longer active.

Question 10

Role of the PFC:

Answer 10

PFC activation reflects a representation of task goal in working memory.
Working memory involves interaction between PFC and other brain areas containing perceptual and long-term knowledge relevant to the goal.
Petrides’ model suggests a division of functions within the PFC: manipulation and monitoring in the dorsolateral PFC, maintenance and retrieval in the ventrolateral PFC.
Storage of information occurs in the posterior cortex.

Question 11

STM separate from LTM?

Answer 11

Modal Model proposes separate stores for STM and LTM.
Baddeley’s WM model extends the model but retains the idea of separate stores.
Strong evidence from neuropsychological and behavioral studies.
Patient H.M. had impaired LTM but intact STM.
Patient K.F. had normal LTM but small STM span.

Question 12

Unitary Models of WM/STM:

Answer 12

Working memory is temporary activation of long-term memories.
Capacity limitations explained by interference.
Cowan’s WM model suggests central executive/attention selects and activates LTM representations.
Cognitive neuroscience evidence supports the idea that WM and LTM are not completely distinct.

Question 13

PFC and LTM Memory:

Answer 13

PFC is diverse and associated with higher cognitive functions.
In WM, PFC serves as the site of the central executive.
PFC is involved in maintenance and active control of information represented in LTM systems.
PFC functions are also prevalent in encoding and retrieval tasks.

Question 14

PFC and Memory Encoding:

Answer 14

Lateralized responses in PFC during encoding depend on the type of materials.
Left PFC involved in encoding words or semantic materials.
Right PFC involved in encoding spatial information or faces.

Question 15

PFC subsequent memory effect for clustered recall (Long et al., 2010):

Answer 15

Dorsolateral prefrontal cortex (DLPFC) activation predicted subsequent semantic clustering.
Ventrolateral prefrontal cortex (VLPFC) activation predicted subsequent recall, whether clustered or non-clustered.

Question 16

PFC and retrieval:

Answer 16

PFC regions aid in the organization, selection, monitoring, and evaluation of processing during retrieval.
Fletcher and Henson, 2001: DLPFC involved in monitoring what has been retrieved from LTM.
Increased DLPFC activity with increased demands or need for monitoring retrieval (e.g., free recall, recall, low confidence judgments).
PFC damage results in more severe impairment in free recall compared to recognition tasks.

Question 17

Free recall:

Answer 17

Minimal cues at test to aid memory performance.
Involves strategic search, organization, selection, and evaluation of retrieved information.

Question 18

Source Monitoring and PFC:

Answer 18

Relates to the ability to attribute retrieved memories to their original context.
PFC is involved in placing an event in context through active evaluation processes.
Necessary for accessing the origin of the memory.