You Are Your Memory
Your memory stores:
• Your personal experiences
• Emotions
• Preferences/dislikes
• Motor skills
• World knowledge
• Language
Fundamentally, you as a person are derived from
experiences that have been stored in your
nervous system.
This is possible only because your brain has
developed the capacity to store information.
Figure 1.1 Learning and memory explain the fact that our past experience
influences our behavior
Definition
“Learning is the process of acquiring new
information, while memory refers to the persistence
of learning in a state that can be revealed at a later
time” (Squire, 1987).
Goal of Neurobiology
The goal of neurobiologists is to understand how
the brain acquires, stores, and maintains
representations of experience in a persistent state
that permits the information contained in the
representation to be retrieved and influence
behavior.
Two Approaches to the Study of Memory:
Psychological and Neurobiological
Study of memory used to be the sole territory of
psychologists. However, today neurobiologists also
have weighed in.
Psychological Approach:
The general goal of psychology is to (a) derive a set
of empirical principles that describe how variation in
experience influences behavior, and (b) provide a
theoretical account that can explain the observed
facts.
Ebbinghaus and Memory
Hermann Ebbinghaus developed
the first scientific methods for
assessing the acquisition and
retention of a controlled
experience. To study “pure
memory” required a methodology
that could separate what the
subject already has learned from
what the subject is now being
asked to remember. So he
invented the nonsense syllable.
Figure 1.2 Ebbinghaus documented the first forgetting curve
Figure 1.3 Single-trace and dual-trace theories of Ebbinghaus’s forgetting
curve
Psychologists Only Study Memory at a Single Level of Analysis
Psychologists study only the
relationship between
experience and behavior.
This means they do not
directly manipulate or
measure brain processes.
Neurobiologists Are Motivated by the Belief that Memory Traces
Have a Physical Basis in the Brain
To understand the physical
basis of memory requires a
multiple level approach. Not
only is the brain
manipulated, responses in
the brain to experience and
drugs are measured. Thus
neurobiologists study brain
systems, synapses, and
molecules, as well as
behavior.
Historical Foundations: The Golden Age
About 30 years ago Paul Rozin
described the last decade of the 19th
Century as the “Golden Age of
Memory” because during that era
many of the basic phenomena and
ideas that still occupy researchers
emerged.
Paul Rozin
Historical Foundations: The Golden Age
Théodule Ribot proposed that during
disease of the brain, memories
disappear in an orderly fashion.
The Dissolution of Memory
First
Last
Historical Foundations: The Golden Age
Ribot’s Law: Ribot also proposed that old memories are more
resistant to disease/disruption than new memories.
Historical Foundations: The Golden Age
Serge Korsakoff
Described the syndrome produced by
alcohol now called Korsakoff’s Syndrome.
The syndrome is characterized by what we
would now call anterograde amnesia—the
inability to acquire new memories.
During the late stages there is also
retrograde amnesia—the loss of memories
acquired before the onset of the disease.
He also proposed that amnesia could be
due to either storage failure or retrieval
failure.
Historical Foundations: The Golden Age
William James proposed that memories
emerge in stages. An after image is
supported by a very short-lasting trace,
then replaced by the primary trace that
also decays. Secondary memory is viewed
as the reservoir of enduring memory trace
that with an appropriate retrieval cue can
be recalled.
Figure 1.6 William James proposed that memories emerge in stages
Historical Foundations: The Golden Age
Santiago Ramón y Cajal
The Neuron Doctrine: The
idea that the brain is made
up of discrete cells called
nerve cells, each delimited by
an external membrane.
The Synaptic Plasticity
hypothesis: The idea that the
strength of a synaptic
connection can be modified
by experience.
Historical Foundations: The Golden Age
Ivan P. Pavlov
Developed the
fundamental
methodology for
studying associative
learning in animals.
In the Pavlovian conditioning method, two events called the
CS and US are presented together. Subsequently, the CS
evokes the response called the CR. Psychologists assume
that the CS evokes the CR because the CS gets associated
with the US. Psychologists and neurobiologists continue to
use this method to study associative learning in animals.
Figure 1.8 Pavlovian conditioning is widely used to study learning and memory
in animals
Historical Foundations: The Golden Age
Edward L. Thorndike
Developed the first methodology for studying how
we learn about the consequences of our actions.
This methodology is called instrumental
conditioning. Some people also call it Thorndikian
conditioning.
The Law of Effect: The correct behavior was
learned because the consequences of successful
outcome (a satisfying state) strengthened
connections between the stimulus (S) and correct
response (R) and the consequence of
unsuccessful responses (annoying state) weaken
the competing and wrong S–R connections.
Figure 1.9 Edward L. Thorndike invented the methodology for studying
instrumental learning
W. W. Norton
W. W. Norton
W. W. Norton
Baddeley, A., and Hitch, G., Working Memory, in Bower, G.H. (Ed.), The Psychology of Learning and
Motivation, Vol. 8. New York, Academic Press, 1974, pp. 47–89. Adapted by permission of the publisher.
W. W. Norton
W. W. Norton
W. W. Norton
W. W. Norton
Memory & Brain
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Henry Gustav Molaison (1926 – 2008)
Patient H.M.
“Right now I'm wondering, Have I done
or said anything amiss? You see, at
this moment everything looks unclear
to me, but what happened just before?
That's what worries me. It's like waking
from a dream; I just don't remember.”
“Every day is alone in itself, whatever
enjoyment I've had, and whatever
sorrow I've had.”
-- H.M.
Neuropsychology
patients
Memory Systems in the Brain
Medial temporal lobe amnesia
• Inability to form new explicit memories
(anterograde amnesia)
• Good IQ, good implicit learning
• Loss of memories from before injury
(retrograde amnesia)
• Working/Short-term Memory
– Can carry on a normal conversation
– Normal memory span
• Intelligence and Language Normal
– Note that some of these rely on spared
retrograde memory (vocabulary, math rules, etc)
• Skill Learning
– “motor, perceptual, or cognitive operations or
procedures that are typically acquired through an
incremental and slow process of repetition.
– Mirror reading
– Rotary Pursuit
– Artificial Grammar Learning
– Perceptual Classification
– Tower of Hanoi (not reliable!)
Memory Systems in the Brain
Memory activates hippocampus
Memory Systems in the Brain
Memory Systems in the Brain
Memory Systems in the Brain
Memory Systems in the Brain
Memory Systems in the Brain
W. W. Norton
Patient EP
Memory
Teng & Squire, 1999
Hippocampus & memory
But see patients like …
Long-term retrograde amnesia… the crucial role
of the hippocampus
Lisa Cipolotti, Tim Shallice, Dennis Chan, Nick Fox, Rachel
Scahill, Gail Harrison, John Stevens, Peter Rudge
Neuropsychologia 39 (2001) 151–172
Patient VC shows bilateral hippocampal loss with no involvement
of entorhinal cortex or temporal neocortex
Hippocampus & memory
Memory for major public events
Hippocampus & memory
Memory for famous faces
Hippocampus & memory
Autobiographical and semantic memory
Hippocampus & memory
Anomalies for standard view
1. Variation in RA duration - 72 hr to 35 years
2. Examples of flat gradients - experimental and
clinical
3. RA with no anterograde amnesia
(less specificity in RA)
LTP, not the expression of LTP
The Polar Opposite of Long-Term Potentiation
Review: A Core Signaling Cascade
• Glutamate is released from the
presynaptic or sending neuron.
• Glutamate binds to both AMPA and
NMDA receptors.
• The cell is depolarized when enough
Na+ enters the cell through AMPA
receptors.
• The combination of binding
glutamate to the NMDA receptor and
depolarizing the cell removes the Mg+
plug from the NMDA channel.
Figure 3.1 First messengers carry information between neurons; second
messengers carry the signal into the neuron
Functional Endpoints: A General Framework
The Dynamic Life of AMPA Receptors
W. W. Norton
Unilateral cerebellar cortex lesion