Memory (L10-11)

Question 1

What area is essential in memory?

Answer 1

• Medial temporal lobe structures (particularly hippocampus)

Question 2

Patient HM

Answer 2

• Removal of bilateral hippocampus and MTL as treatment for epilepsy
• Developed anterograde amnesia (can’t form new memories) and retrograde amnesia (unable to retrieve memories prior to surgery)
• Memory impairment was independent of the sensory modality involved
• His long-term memory deficit is limited to his declarative memory: retrieval of life events (episodic memory) and factual information (semantic memory)
• His non-declarative memory, working memory and IQ remained normal
• Recency effect of working memory is unaffected unless distracted

Question 3

What does patient HM tell us about the medial temporal lobe?

Answer 3

• Important for long-term memory, but less so for working memory functions
• Important for remembering recent events but not for more remote memories
• Important for explicit memory regardless of the encoding or retrieval modality
• Important for transferring events and facts into long-term memory
• Not important for retaining information (working memory) or for memories linked to skills (non-declarative memory)

Question 4

Single dissociation

Answer 4

When a manipulation leaves one cognitive function intact whilst impairing another

Question 5

Double dissociation

Answer 5

• When there is another manipulation that does the reverse
• Patient KF has damage to left temporo-parietal junction = impaired STM and preserved LTM
• Patient MH has damage to bilateral temporal lobe = preserved STM and impaired LTM

Question 6

Episodic memories

Answer 6

Based on experiences (familiarity and recollection)

Question 7

Semantic memories

Answer 7

Language and other learned knowledge

Question 8

Spatial memory

Answer 8

• Rat brain builds up mental spatial representation of maze
• If the hippocampus is damaged in rat that has learned the location of platform in Morris water maze, it reverts to random patterns of searching
• Greater hippocampal activity in London taxi drivers when answering spatial questions

Question 9

Cognitive map theory

Answer 9

• Proposed by O’Keef + Nadal

- Hippocampus mediates memory for spatial relations among objects in the environment

Question 10

Relational memory theory

Answer 10

• Proposed by Eichenbaum et al.
• Hippocampus does not represent space, but more the relationships among overlapping cues in the environment
• Rats with a lesion in the fornix (disrupts hippocampus communication) leads to problems in memory for overlapping relations

Question 11

Episodic memory theory

Answer 11

• Proposed by Tulving + Moscovitch
• Hippocampus is critical for episodic but not semantic memory

EVIDENCE

• Retrograde amnesia: patient KC has damage to the hippocampus, can’t remember episodic memories prior to the accident but has preserved intellectual abilities and is able to retrieve semantic memories
• Anterograde amnesia: patient HM is able to learn new semantic facts
• Developmental amnesia: individuals perform poorly on tests of episodic memory but not working memory and learn normally in school

Question 12

Semantic dementia

Answer 12

• Patients have difficulty naming items (anomia) or understanding their functions
• Caused by damage to the anterior temporal lobe
• Individuals have preserved episodic memory but impaired semantic memory

Question 13

Integrating theories of hippocampal memory function

Answer 13

1. Cognitive map and relational memory theories could be linked to different hippocampal regions
   - Spatial memory is linked to posterior/right hippocampal processing
   - Relational functions are linked to anterior/left hippocampal processing
2. Relational memory and episodic memory are suggested to be closely related through episodic recollection
   - Lesions in rat hippocampus have a significant effect on recollection (episodic memory) but not familiarity

Question 14

Subsequent memory effect

Answer 14

• Participants are asked to remember abstract/concrete words and upper/lower case words
• In the lateral prefrontal cortex, there is a difference between the words remembered and forgotten
• Known as the DM effect (difference due to memory)

Question 15

Frontal lobes

Answer 15

• Patients and controls were asked to learn new facts, then tested after a delay using recall and recognitions tests
• Patients remembered the facts but patients with frontal lobe damage show declarative memory problems in semantic source memory (claim to have previously known the fact)
• Retrieval cue > memory search > recovery of memory > monitoring process (reject untrue memories)
• Damage to the frontal lobes may cause problems with the monitoring process
• Remembering is associated with the left dorsolateral prefrontal cortex
• Monitoring and familiarity is associated with the right dorsolateral prefrontal cortex

Question 16

Working memory

Answer 16

• Made up of central executive, phonological loop and visuo-spatial sketchpad

Question 17

Central executive

Answer 17

• Regulates information flow between the subsystems

- Prefrontal cortex and parietal cortex are involved with executive functions

Question 18

Phonological loop

Answer 18

• Phonological store and a phonological rehearsal process
• Disrupted by articulatory suppression
• Increasing the load (eg. more syllables) requires increased rehearsal/maintenance = increased activation in the dorsolateral prefrontal cortex (front)
• Increasing the number of items requires increased demand on store = increased activation in the supramarginal gyrus (back)

Question 19

Visuo-spatial sketchpad

Answer 19

• Visual/spatial/tactile information processing and short-term storage
• Disrupted by concurrent visual/spatial dual tasks

Question 20

What is the role of the prefrontal cortex in working memory?

Answer 20

• Delayed response task: food is placed into a well (cue), screen is lowered to cover the food (delay), monkey reaches for well the food was placed in when screen is raised (response)
• Cells in the prefrontal cortex continue to respond in the delay interval suggesting a role for the prefrontal cortex in the maintenance of information in working memory

Question 21

What is the cause of lesions to the…

• Temporal cortex
• Parietal cortex

Answer 21

• Lesions to the temporal cortex affect visual working memory
• Lesions to the parietal cortex affect spatial working memory

Question 22

Memory decline

Answer 22

• Older people have impaired working memory abilities, linked to reduced prefrontal cortex activity
• Older people with intact memory ability show even greater prefrontal cortex activation than younger controls (working harder to maintain performance levels and to compensate)
• Stimulant drugs linked to dopamine receptors improve memory performance in aged monkeys

Question 23

What are the 3 components of implicit memory?

Answer 23

1. Skill learning
2. Priming
3. Conditioning

Question 24

Skill learning

Answer 24

• Includes perceptual, motor or cognitive skills
• Some situations require the use of knowledge built up over many prior experiences to generate a reliable predictive model

Question 25

What areas are important for…

• Explicit/declarative memory
• Implicit/procedural memory

Answer 25

• Hippocampus is important for explicit/declarative memory

- Basal ganglia is important for implicit/procedural memory

Question 26

Probabilistic learning weather task

Answer 26

• Participants are given 3/4 symbols and are required to predict the weather
• None of the images alone allow total accuracy
• Participants must build up a probabilistic model of different combinations of image that best predict the weather
• Caudate nucleus (part of the basal ganglia) activation increases over successive trials
• Normal participants initially focus on one image and use declarative, episodic (hippocampal) memory but eventually switch to non-declarative (basal ganglia) memory
• Amnesic patients have poor declarative memory, but their performance improves over time due to the switch to non-declarative memory
• Patients with Parkinson’s continue to adopt the declarative memory strategy so their performance declines due to the damaged basal ganglia

Question 27

Perceptual priming

Answer 27

• Neural responses diminish to subsequent presentation of the same items
• Brain areas that show reduced activation during repitition suppression include the left ventrolateral prefrontal cortex, left occipital cortex and fusiform cortex
• Left fusiform gyrus shows a repetition suppression effect for same and different exemplars (eg. 2 different colour cars) = semantic processing
• Right fusiform gyrus shows a repetition suppression effect for same exemplars only
  = perceptual processing

Question 28

Conceptual priming

Answer 28

• Participants are given 2 tasks in which they are asked to determine whether words are concrete/abstract words and lower/upper case
• Left anterior inferior frontal gyrus shows suppression within-task only = involved in semantic processing
• Left posterior inferior frontal gyrus shows suppression within and across task = is involved in phonological processing

Question 29

Semantic priming

Answer 29

• Participants are presented with a word and then are shown a semantically related word
• Semantic repetition shows a reduction in activity in the anterior temporal lobe