Neuropsychology of Memory

1
Neuropsychology of Memory

• Dr Julie Hulme
• j.a.hulme_at_staffs.ac.uk
• [phone]

2
Plan

• Defining terms
• Look at some case studies that illustrate the
  relationship between brain structure and function
  with regard to human memory
• Update with brain scanning
• Make links with cognitive psychology

3
What is Neuropsychology?

• The study of the neural substrate underpinning
  human cognitive function
• Often uses case studies from brain damaged
  patients
• Some use of brain scanning techniques recently

4
Some Terminology

• Semantic memory memory for facts, general
  knowledge
• Episodic memory memory of events
• Declarative memory memory of which you are
  consciously aware knowing that
• Procedural memory knowing how
• Short-term and long-term memory
• Anterior vs posterior

5
Anterograde vs Retrograde Amnesia

• Antero looks forward
• The inability to form new memories after a trauma
• Retro (like fashion) looks back
• The inability to remember things from before the
  trauma

6
The Case of KF

• Shallice and Warrington (1970)
• Motorbike accident resulting in brain damage
  left parieto-occipital lobe (next slide)
• LTM unimpaired
• STM severely impaired digit span and free
  recall (poor if more than one item in list)

7
The Case of KF
8
Conclusions from KF?

• LTM and STM are stored in different locations in
  the brain

9
The Case of HM

• HM had severe epilepsy surgery (1953) to treat
  this involved bilateral removal of his medial
  temporal lobes

10
The Case of HM Medial Temporal Lobes

• The medial temporal lobes include the
  hippocampus, amygdala and surrounding cortical
  tissue

11
(No Transcript)
12
The Case of HM Outcome of Surgery

• Seizures were alleviated
• Severe memory impairment
• Anterograde amnesia inability to recall events
  that have happened since the operation
• Very little effect on memory of events from
  before the operation
• Studied by many researchers (e.g. Scoville and
  Milner, 1957 Salat et al., 2006)

13
The Case of HM In His Words

• Every day is alone in itself, whatever enjoyment
  Ive had, and whatever sorrow Ive had Right
  now, Im wondering. Have I done or said anything
  amiss? You see, at this moment everything looks
  clear to me, but what happened just before?
  Thats what worries me. Its like waking from a
  dream I just dont remember
• Milner (1970, p37).

14
The Case of HM

• Has to be reintroduced to his doctors every day
• Cannot store new episodic memories
• But can learn new procedural memories, such as
  mirror drawing despite not remembering that he
  can (Milner, 1965)

15
The Case of HM Verbal Memory

• Language was unimpaired, and reading and writing
  are still intact
• However, HMs language contains no words/phrases
  learned since his operation
• For example, when asked to define flower child,
  he said it was a young person who grew flowers
• STM unimpaired

16
The Case of HM Cued Recall

• Has learned some new semantic knowledge since the
  operation
• Using first names as cues, HM can select the
  correct surname of famous people who have become
  famous since his surgery (OKane et al., 2004).
• Could also pick the famous name out of a pair
  one celebrity and one name from the phone book
  with 88 accuracy (same rate as age matched
  controls).

17
The Case of HM What Happened?

• Problems with declarative memory (knowing that),
  especially episodic memory (events)
• But not procedural memory knowing how (mirror
  drawing)
• Involved in formation of new memories but not
  storage of old ones (language and episodic)
• Some semantic (facts) learning
• Role of hippocampus?

18
Hippocampus and Amnesia

• Hippocampus implicated in amnesia Reed
  Squire, 1997 MRI study of 6 amnesic patients,
  all reduced size of hippocampus.

19
The Case of Clive Wearing An Unforgettable Love
Story
20
The Case of Clive Wearing

• Baddeley (1990)
• Talented musician and conductor
• Viral encephalitis (Herpes simplex)
• Bilateral damage to temporal lobe including
  hippocampus, plus some damage to his left frontal
  lobe
• Amnesia mostly anterograde, but some retrograde
  amnesia
• Damage to frontal lobes led to repetitive speech
  and highly emotional behaviour
• No effect on general cognitive abilities

21
The Case of Clive Wearing

• A moment-to-moment existence
• Wife, Deborah, visits greets as if its the
  first time he has seen her for years, even if she
  has been out of the room for just moments
• Remembers he is married, remembers who she is
  when she is not there, and that he loves her
• But cannot remember his wedding day, and cannot
  remember seeing her recently
• Keeps a diary I have just woken up - and used
  to ring her constantly Ive just woken up after
  such a long time. I havent spoken to anyone
  yet, but I wanted to tell you.

22
The Case of Clive Wearing

• Can still play organ, sing and conduct with
  extraordinary talent
• Procedural memory intact
• STM unimpaired
• But episodic memory, declarative memory severely
  impaired

23
Further information

• Observer interview with Deborah Wearing
  http//observer.guardian.co.uk/magazine/story/0,11
  913,1394684,00.htmlarticle_continue
• Videos showing Clive Wearing available from
  http//www.youtube.com/watch?vOmkiMlvLKto

24
Conclusions from Case Studies?

• The hippocampus is involved in the storage of
  long-term declarative memories
• But is not the actual store of these memories
• The hippocampus is not involved in procedural
  memory
• Different types of LTM are stored using different
  processes and in different places

25
Case of KC (Rosenbaum et al., 2000)

• Brain injuries in traffic accident
• Damage to left frontal-parietal and right
  parietal occipital cerebral cortex shrinkage of
  hippocampus and parahippocampal cortex
• Cannot remember anything from his personal past
  (episodic)
• General knowledge good (declarative)
• E.g. plays chess well but doesnt remember
  learning
• Struggles to learn new semantic knowledge,
  definitely cannot learn new episodic information
• Compare to HM similarities and differences?

26
Comparison of HM and KC

• Both have anterograde amnesia inability to form
  new episodic memories
• But KC also has profound retrograde amnesia
• NOT due to hippocampal damage
• Retrograde amnesia probably results from damage
  to the anterior cortex

27
Memory Has Temporal Stages

• Atkinson and Shiffrin (1968)

28
Short-Term Memory

• Used differently by different authors
• Cognitive psychologists often mean just a few
  seconds
• Miller (1956) Magic 7 (72 chunks)
• Biological psychologists may mean any memory
  which is not permanent, lasting for minutes or
  hours, up to a day

29
Intermediate Term Memory

• Not often discussed in cognitive psychology
• We sometimes need to hold information for a day
  or so
• What do you need to buy when you go shopping?
  Where did you say youd meet your friend, and at
  what time?
• ITM McGaugh, 1966 Rosenzweig et al., 1993

30
Long Term Memory

• Memory lasting days to years
• Infinite capacity think how many words and
  facts you can remember
• Solomon Shereshevskii studied by Luria (1968)
  mnemonist and synaesthetic (smelt sounds and
  heard sights!) couldnt forget

31
Forgetting

• Most of us remember things we learned most
  recently better than we remember things from a
  long time ago
• The case studies weve looked at tell us that
  this might be because theyre stored in different
  places
• Brain imaging confirms this

32
Brain Imaging Studies

• Confirm that the hippocampus is important in
  formation of new declarative memories
• Active during encoding and retrieval stages

33
fMRI Scanning

• Remember this face visual areas
• Think about this face HPC
• 3. 4. Compare this face to another visual
  areas frontal lobes (decision making)
• DEsposito and Rangapath (2000)

34
Episodic Memory

• Listening to an autobiographical passage being
  read caused increased activation of the right
  frontal and temporal lobes compared to listening
  to a non-autobiographical passage (Fink et al.,
  1996)

35
Normal Participants

• Ask participants to name tools or animals
• Region of cortical activation differs depending
  on category (Martin et al., 1996) with some
  overlap
• Cortical mapping of memory is regionalised

36
Brain Scans Confirm Patient Studies

• Both show that the HPC is involved in early
  memory storage and retrieval
• Both show that the cortex is the permanent store
  of memories
• Both show that different types of memories are
  stored in different parts of the brain

37
Cognitive Psychology and Neuropsychology

• Produce similar results
• Cognitive Atkinson and Shiffrin and later
  models emphasise temporal stages of memory
• Neuropsychology different parts of the brain
  active during these different stages different
  parts of the brain store different kinds of
  memory
• The two models can be mapped onto each other

38
Cognitive and Neuropsychological Models
Sensory cortices
Prefrontal cortex
Hippocampus
Permanent storage in cortex
39
Summary

• Looked at the different parts of the brain which
  are involved in memory
• Case studies and brain scanning confirm the roles
  of key brain areas
• Neuropsychological findings are largely
  consistent with models of cognitive psychology