The Neuropsychology
of Memory
Ch. 11
Outline
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Case studies
Korsakoff’s Amnesia
Alzheimer’s Disease
Posttraumatic Amnesia
Clive Wearing video
Theories of consolidation
The Case of R.B.
• R.B. suffered ischema-produced brain
damage during heart-surgery; subsequently,
R.B. displayed a pattern of amnesic deficits
similar to, although less severe than, that of
H.M.
The Case of R.B.
• After R.B. passed away, a postmortem examination
revealed damage to the pyramidal cell layer of the CA1
hippocampal subfield, but no other obvious damage
• This supported the original hypothesis that H.M.’s deficits
were attributable to his hippocampal damage, rather than
to damage to other medial-temporal-lobe structures… as
we shall see, this may not be the case
Korsakoff’s Amnesia
• Individuals who chronically consume
alcohol develop a pattern of behavioral
disorders commonly referred to as
Korsakoff’s syndrome
• In addition to severe anterograde amnesia,
Korsakoff patients suffer from a severe
retrograde amnesia
Korsakoff’s Amnesia
• Although their retrograde amnesia is more
severe for recent memories, it also affects
their memory for events occurring many
years before the diagnosis of their case (i.e.,
for remote events)
Korsakoff’s Amnesia
• The brain damage associated with
Korsakoff’s amnesia is diffuse, although the
amnesia is usually attributed to the
mediodorsal nuclei of the thalamus
The Case of N.A.
• N.A. is a patient who was accidentally
stabbed in the brain through the right nostril
by a friend with a fencing foil; he suffered
both retrograde and anterograde amnesia
Korsakoff’s Amnesia
• A subsequent MRI revealed extensive
damage in the mediodorsal thalamic nuclei
and the mammillary bodies, providing
support that these structures are important
in mnemonic function
• However, despite this evidence, it is
unlikely that Korsakoff’s is due to damage
to any single brain region
Alzheimer’s Disease
• Major cause of amnesia; the first symptom
is often mild loss of memory
• Disease is progressive; eventually the
dementia becomes severe enough to
incapacitate the patient
Alzheimer’s Disease
• Considerable attention has been focused on
predementia Alzheimer’s patients; in
addition to both anterograde and retrograde
amnesia, these patients often display
deficits in short-term memory and some
forms of implicit memory (those involving
verbal or perceptual material, but not
sensorimotor learning)
Posttraumatic Amnesia
• Blows to the head can lead to a disturbance
of consciousness (concussion), a complete
loss of consciousness (coma) and
posttraumatic amnesia (loss of memory
due to a non-penetrating head injury)
Posttraumatic Amnesia
• Patients with posttraumatic amnesia
generally have both anterograde and
retrograde amnesia; in general, the
anterograde amnesia is longer than the
period of coma that produced it, while
duration of the coma lasts longer than the
period of retrograde amnesia that it
produced
Amnesia
Clive Wearing video (in class)
Amnesia
• The retrograde amnesia seen after
concussion or coma is typically worse for
the most recent memories; this led to the
suggestion that older memories are stored in
a more permanent form through the process
of consolidation
Theories of consolidation
• Standard consolidation model
– Information is encoded in associative cortical areas
– Hippocampus integrates info from these distributed
modules and fuses features together into coherent
memory trace
– Successive reactivation of hippocampal-cortical
connections (rapid and transient) leads to strengthening
of cortico-cortical connections (Hebbian learning;
associations that are slow to acquire and long-lasting)
– Cortico-cortical eventually become independent from
hippocampal-cortical
Theories of consolidation
• Multiple trace theory (Nadel &
Moscovitch)
– Memories are encoded in hippocampal-cortical
connections
– Memory reactivation leads to generation of
multiple traces in hippocampus, which are
linked to cortical networks
– Traces in hippocampus provide spatial and
temporal context
Theories of consolidation
– Traces in cortex are context-free in nature (they
are semantic)
– Retrieval of contextually rich episodic
memories always depends on hippocampalcortical networks (these connections never go
away as opposed to standard theory)
– Retrieval of remote semantic memories is
possible in absence of functional hippocampus
Theories of consolidation
– Retained memories become progressively more
resistant to disruption due to hippocampal
damage because
• each time a similar experience occurs OR
• The original memory is recalled
a new engram (change in brain that stores a memory)
is established and linked to the original engram
Brain areas and types of memory
• Inferotemporal cortex: long-term visual
memories
• Amygdala: emotional significance of event
• Prefrontal cortex: working memory
• Cerebellum and striatum: implicit
sensorimotor memories
No lecture Thurs… just Exam 4 review