Transcript RETROGRADE AND ANTEROGRADE AMNESIA

“THE ADVANTAGE OF HAVING
BAD MEMORY IS THAT YOU
CAN ENJOY GOOD THINGS FOR
THE FIRST TIME SEVERAL
TIMES.”
-FRIEDRICH NIETZSCHE
RETROGRADE AND
ANTEROGRADE AMNESIA
Ellie Moradi
Colin Schwartz
Chris Yco
Melissa Bergh
RETROGRADE AMNESIA:
THE UNDERLYING CAUSE &
PHYSIOLOGY
• Inability to access memories prior to
damage
• Often associated with neurodegenerative
diseases such as Alzheimer’s Disease
• Other causes include trauma, tumors,
cerebrovascular accident (aneurysm),
encephalitis, chronic alcohol use, and
hypoxia (lack of oxygen)
HIPPOCAMPUS
MEDIAL TEMPORAL LOBE
Physiology & Causes Cont’d.
• Hippocampal damage
– Hippocampus important for episodic and
declarative memory
– Damage makes it difficult to recall memories
prior to damage
– Retrograde amnesia is both extensive and
ungraded when damage is limited to
hippocampus
– Damage does not interfere with learning
new skills however
Physiology & Causes Cont’d.
• Medial Temporal Lobe damage
– The sparing of remote memory after damage
shows that the importance of the medial
temporal lobe structures for memory
gradually diminish.
– Often damage is done to the knowledge
stores in the MTL affecting the ability to
recollect memories or information regardless
of when it occurred or was learned
RELATION TO ALTERED STATES OF
CONSCIOUSNESS
• Memories and past events are contributing
factors to being an individual
• No studies have shown a complete loss of
self
• The individual adapts to the loss of
memories
Characteristics of RA
• Ribot gradient
– The tendency to lose new
memories more so than
old memories
– Span of loss unique,
difficult to pinpoint it
• Memory loss
– Retain autobiographical,
semantic, procedural,
general knowledge
– Lose episodic (Brandt &
Benedict 1993)
–Trevor Rees-Jones (August 1997)
What can RA tell us about
memory?
• Memory-Consolidation Theory (McGaugh
1966)
– New memory has to be consolidated and if
interrupted leads to RA
– Classical evidence: amnesia inversely related
to the age of the memory (Duncan 1949)
– Problems: RA recovery, delayed-onset RA and
RA for long-term memory (Krickett Carpenter)
What can RA tell us about
memory?
• Multi-trace theory (Nadel et al 2000)
– Hippocampus responsible for encoding and
retrieving all episodic memory independent of
its age and thus damage randomly causes
deficits.
– Old memories well encoded but can have
retrieval problems.
– Evidence? Ribot gradients only found in partial
lesions of hippocampus in rats.
– No real evidence. If you can figure out a way
to test this, let me know.
What can RA tell us about
memory?
• Semanticization (Cermak 1984)
– All memories start out as episodic and
through over-learning becomes semantic
which is independent of hippocampus.
In concluding RA
• Should old memory amnesia be
considered with RA?
• No studies to my knowledge comparing
brain areas involved in new and old
memory RA
• No consensus about RA cause
RA and ASC
• Sense of self endures in RA
• Theoretically if Ribot gradient went ad
infinitum would forget about self?
• In Semantization, if all memory starts out
episodic then awareness externally is
episodic and semantic internally
ANTEROGRADE AMNESIA
• Anterograde amnesia is a selective
memory deficit, resulting from brain injury.
CAUSES OF INJURY
• Stroke
– ischemic stroke, in which a small blood clot becomes
wedged in one of the tiny blood vessels supplying the
brain, blocking the flow of blood. This blood clot may
have formed in the brain, or it may have formed
elsewhere, broken free, and traveled through the blood
stream to reach the brain
• Aneurysm
– An aneurysm is a small local bulge in the wall of a blood
vessel, usually an artery. Normally, blood vessels operate
like pipes, carrying blood throughout the body to cells
which depend on this supply for oxygen and nutrients.
AREAS OF INJURY
• The first, and most well-studied, is the
hippocampus.
– Hippocampus is seen as the gateway through
which new information must pass before
being stored into long term memory.
– Once this is damaged, it is almost impossible
to create new memories.
INJURY CONT’D.
• Long-Term Potentiation (LTP)
– This occurs when the cAMP-activated protein kinase enters the
nucleus of the sensory cell, and activates CREB (cAMP
Response Element Binding protein) to trigger protein
synthesis. This leads to formation of a variant of the same
kinase (cAMP-PK), which is constitutively active, without the
need for cAMP. The K+ channel will then be constantly inhibited.
At the same time, genes for the synthesis of active-zone protein
are promoted, causing increase of the effective synaptic area.
This then is a form of long term memory, and illustrates how
a short term effect can be converted eventually into a long-term
change, in which protein synthesis is required for the transition.
Anterograde Amnesia
• Inability to form new memories.
• Selective memory deficit resulting
predominantly from brain damage.
• Memories prior to the incident are largely
spared.
• Memory for skills or habits are often
spared as well.
Characteristics of AA
• Memory lapses may be triggered by
nervous or upsetting environments
• Stuck in a previous time period in own life
• Most carry on lives normally and happily,
until reminded of their deficit by others or
out of place objects or activities.
Hollywood Anterograde Amnesics
• Finding Nemo (2003)
• Memento (2001)
• 50 First Dates (2004)
Clinical AA
• The infamous Patient H.M. (Bilateral Temporal
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Lobectomy)
Oliver Sack’s Lost Mariner: Jimmie G.
(Korsakoff’s Type)
Oliver Sack’s William Thompson (Korsakoff’s
Type with much confabulation)
Oliver Sack’s Stephen R. (Korsakoff’s Type)
AA and Alternate States of
Consciousness
• He screams with terror and confusion, and Sacks
admits there is nothing that can be done to help
him, for like all other anterograde amnesics, he
screams "for a past which no longer exists" (The
Man Who Mistook His Wife For a Hat: p.42).
• Living an existence that is not real
• Never having any ties to reality, which
consists of time
Memory is Consciousness
• You have to begin to lose your memory, if only
in bits and pieces, to realize that memory is
what makes our lives. Life without memory is
no life at all…Our memory is our coherence, our
reason, our feeling, even our action. Without it,
we are nothing…(I can only wait for the final
amnesia, the one that can erase an entire life,
as it did my mother’s…)
-Luis Bunuel
SUMMARY
• Current autobiographical memories form
sense of enduring self?
• As Siegel concluded, neurotransmitters
control consciousness……the fact that
serotonin and ACh are altered suggests
that memory alteration correlates with an
altered state of consciousness.
REFERENCES
• Brandt, Ralph & Benedict, Ralph H. B., (1993) Assessment of
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Retrograde Amnesia: Findings With a New Public Events Procedure.
Neuropyschology, 7:217-227
McNaugh, J. L. (1966). Time-dependent processes in memory
storage. Science 153, 1351-1358
Duncan, C.P. (1949). The retroactive effect of electroshock on
learning. Journal of Comparative and Physiological Psychology, 42,
3244.
Meeter, Martijn & Murre, Jaap M. J., (2004) Consolidation of LongTerm Memory: Evidence and Alternatives, Psychology Bulletin,
130:843-857
Clark, Broadbent, Zola, & Squire (2002). Anterograde amnesia and
temporally graded retrograde amnesia for a nonspatial memory task
after lesions of the hippocampus and subiculum, 4663-4669.