Amnesia and Alzheimer’s

Kim Hyun-woo.

Place photo here

Questions

• What are Amnesia , Alzheimer’s and Dementia?

• Where is Memory?

• What hypothesis can you make from these disease? And Design your own experiments to prove or disprove it.

Contents

• What is Amnesia?

• Classifying Amnesia.

• H.M. : A Case Study

• 3 experimental ways (free recall, recognition, cued-recall )

• What is Alzheimer?

• Memory Span

• Working Memory

• Autobiographical Memory

• Semantic Memory

• Implicit Memory

• Location of Memory and the role of hippocampus.

Amnesia ( From Wikipedia )

• Condition in which memory is disturbed

• the inability to imagine the future.

• amnesiacs with damaged hippocampus cannot imagine the future.

(Reference) Patients with hippocampal amnesia cannot imagine new experiences

Dementia ( From Wikipedia )

• Etymology

from Latin de- "apart, away" + mens (genitive mentis) "mind")

• the progressive decline in cognitive function due to damage or disease in the body beyond what might be expected from normal aging.

• reversible or irreversible, depending upon the etiology of the disease.

• Alzheimer's disease (AD) is the most common form of dementia.

• This is incurable, degenerative, and terminal disease.

• Irreversible , not known etiology.

Amnesia ( Category )

• Retrograde (partial or complete) / Anterograde

• Cause

• Location of the brain damage

particular parts in the brain are implicated in memory and amnesia

• Functional deficit

H.M. : A case study

• 27 years old

• For alleviating chronic epileptic seizers

surgeons severed his hippocampus

• Alleviation of seizers

• But, severe disruption of memory

• Normal on immediate tests , otherwise no memory on delayed test.

Theoretical Accounts of Amnesia(1)

• Hippocampus is involved in mediating memory.

Cons. - maybe surgeons damaged other parts

• Short term memory / Long term memory

Cons.- short memory span doesn’t mean an impaired long term memory.

• More recent claim, procedural / declarative memory

According to Cohen & Eichenbaum, amnesiacs can learn the solution of the Tower of Hanoi problem. (still controversial)

　 Amnesiacs Control subjects

First Day 48.6 46.7

Forth Day 34.1 33.5

Optimal Performance 31

Theoretical Accounts of Amnesia(2)

• Implicit and explicit Memory (chapter 7)

• Retrieval Problem

TestControl subjects

Amnesic Subjects

Recall 48 % 14 %Recognition 94 % 59 %

Fragmented Word ( Cued-Recall )

96 % 94 %

Theoretical Accounts of Amnesia(3)

• The role of context

Theoretical Accounts of Amnesia(4)

• Amnesiacs can use familiarity on many tasks, this use is impaired relative to controls.

• Control subjects can use familiarity and conscious recollection.

Alzheimer’s Disease(AD)

• Reported the first case in 1907

• Alzheimer’s Disease is still poorly understood.

• Amyloid plaques , neurofibrillary tangles are abnormal structure in the brain of AD patients

• Beta amyloid is toxic to neurons

Alzheimer’s Disease(AD)

Difficulties to understand

- No symptom

- Significant cognitive decline with no obvious cause

- As the disease progresses, more areas are affected

- MRI,CT are useless

- PET, fMRI are sometime useful

Amnesia vs Alzheimer’s

　 Amnesia Alzheimer’s

delayed free recall X X

recognition X X

procedural learning O X

priming O X

X : impaired

O : intact

Alzheimer’s

• In the early stages of disease, even though decreased memory performance,

the bow shape of serial curve

• Short memory span

• Small working memory ( Figure 8.8 )

Alzheimer’s ( Autobiographical memory )

Bow-shaped serial position curve

Alzheimer’s( Semantic memory )

• Alzheimer’s patients tend to represent objects in term of concrete dimensions such as size instead of abstract dimensions

Where is memory?

• Localized vs Distributed

• H.M. Case : hippocampus serves the important role of memory.

• During intentional memory encoding and retrieval, universal activation.

• On evolutionary grounds, Reliance on a central memory organ would also be problematic.

Questions

• What are Amnesia , Alzheimer and Dementia?

- Skip

• Where is Memory?

- I agree with the point of view that memory is distributed.

• What hypothesis can you make from these disease? And Design your own experiments to prove or disprove it.

- Procedural memory is longer than Declarative memory.

Q & A