Download Neurobiology of Learning and Memory Learning and Memory

Stephan Anagnostaras
Several modern disciplines study
neurobiology of learning and memory
My view on learning and memory
Neurobiology of
Learning and Memory
For this class:
Field is broad and the breadth is important,
so we will follow good examples to keep
depth
Several different fields cover learning and
memory. My view is there should be one
field and we would all be in the learning
and memory building. Course will come
from an eclectic perspective
Learning and Memory
Psychology
• Behavioral Neuroscience
• Cognitive Neuroscience/Neuropsychology
Why learning and memory?
Physiology
• Synaptic Plasticity
A relatively permanent change in behavior as the result of
experience - BF Skinner
Biology
• Neuroethology of birdsong learning
Learning versus Memory
Historically there was deep animosity between
behavioral & cognitive psychologists. Why?
Problem relates to view of associationism.
Behaviorism - the cornerstone is behavior
because it is observable. Goal is to find lawful
relationships between external events & behavior
Cognitive psychology - a key tenet is the
concept of an internal representation. This is
how knowledge is stored, and operations can
occur between representations. Can usually only
be inferred or known through introspection.
Memory - current views from in information
processing theory (cognitive psychology and
computer science).
The capacity to store and retrieve of information (comp sci)
The faculty of the mind by which it retains the knowledge of
previous thoughts, impressions, or events. (cognitive psych)
Origins of the study of L&M
Molecular Genetics
• reverse, forward, and epigenetic approaches
Learning - current views on this term are from the
field of learning theory/behavioral psychology.
• The study of learning is closely related to the
beginning of experimental psychology (around 1900)
and, before that epistemology (philosophical study of
how we have knowledge)
Nature-Nurture Debate
Renee Descartes (1641)
Nativism - knowledge is innatively given - e.g.,
knowledge of God, perfection, infinity
Rationalism - knowledge gained by reasoning logic
and intuition.
–In both instances, knowledge is independent of
experience
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Origins of the study of L&M
Origins of the study of memory
Aristotle (350 BC) - 4 laws of memory
1. Similarity
2. Contrast
3. Contiguity
4. Frequency
John Locke (1690)
Empiricism (Associationism) knowledge is gained by experience
as provided to the mind by the senses.
-these views advanced by others
- esp David Hume in the 1700s
Ebbinghaus (1885)
Used introspection to study forgetting in himself
list of 12-16 consonant-vowel-consonant
(CVC) nonsense syllabus (e.g., KEG, MIW)
memorize the list by repeating until recalled,
then record # of trials and wait 20 min - 31 d
Relearn the list = SAVINGS
• Most forgetting in first 20 min, very little between
20 min and 31 d
-Enquiry concerning human understanding, 1748
Origins of the study of memory
Origins of the study of memory
Ebbinghaus also discovered serial position effect
(primacy & recency effects)
Glanzer, M. & Cunitz, A.R. (1966). Two storage mechanisms in free recall. Journal of
Verbal Learning and Verbal Behavior, 5, 351-60
Origins of the study of memory
Serial
position
effect is
ubiquitous
William James (1890)
• argued there must be at least
two types of memory
Primary memory
-information currently contained
in consciousness
Secondary memory
-stored information which can be brought into
consciousness
First of many suggestions that there were multiple
memory systems.
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Origins of the study of memory
Origins of the study of learning
Behaviorists tended to be somewhat hostile and
engaged in many turf battles
The study of memory developed into information
processing theory in the 1960s
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Multi-store Memory System
Sensory Memory
Short Term Memory
Long Term Memory
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Information Processing in Memory
Encoding
Storage
Retrieval
Behaviorist Tradition
In the domain of clinical psychology they were
battling it out with the psychoanalytic approach.
Very much against introspection, tended to become
extreme in this domain, and rejected cognition as
well.
In the domain of animal behavior, they were
battling it out with the ethologists. Ethologists
believed everything was innate and nothing was
learned, hence behaviorists believed nothing was
innate and everything learned.
Behaviorism
Behaviorism focuses on objectively observable behavior
and discounts unobservable mental activities.
John B Watson, the
father of American
Behaviorism
Behaviorists mostly studied animal and human learning
focusing on observable behavior and ways to change
behavior. Their studies of learning came to be known
as learning theory and their studies of how to
change behavior is known as behavior modification
– Began a scientific
movement for
Psychology, against
several mystical
squishy fields, esp.
Freudian
Psychoanalysis
• Largely relationships between external stimuli and
events and their ability to influence behavior
Radical behaviorism allows no intervening processes
(e.g., BF Skinner) while other forms are more lenient.
Watson & Rayner's (1920) famous experiment with "Little Albert"
Watson & Raynor's famous experiment with "Little Albert"
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Behaviorism of the time was very antigenetics, in part because of the evil mental
testing movement
Watson & Rayner's famous experiment with "Little Albert"
Give me a dozen healthy infants, wellformed, and my own specified world
to bring them up in and I'll guarantee
to take any one at random and train
him to become any type of specialist I
might select--doctor, lawyer, artist,
merchant- chief, and yes, even
beggarman and thief, regardless of
his talents, penchants, tendencies,
abilities, vocations, and race of his
ancestors - John Watson
John Watson and
Rosalie Rayner
Concept of "Tabula rasa" - organisms
are born as blank slates
Russian Reflexology
Tabula rasa v. intelligence
• Notice our education system is still scarred by
the nature-nurture debate
• “Social scientists” who think everything is
nurture
US
UR
CS
• Mental testers who think everything is nature
Ivan Pavlov
• As a result, very little study of genetics of
learning until 1992
CS-US pairing
Pavlov’s Little Albert
CS
CR
Learning and Performance
Distinction between learning/memory and performance
an important problem in animal and human studies
Learning can only be inferred by performance:
in humans, a response or a change in behavior
in rats, a change in behavior
• Performance may not occur:
CR
Latent learning [Tolman & Honzik (1930)]
Test anxiety
• Require extensive controls
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Operant/Intrumental
Conditioning
Operant/Intrumental
Conditioning
Edward Thorndike
Law of Effect (1911)
“Of several responses made to the
same situation, those which are
accompanied by or closely followed
by satisfaction to the animal will, all
other things being equal, be more
firmly connected with the situation, so
that, when it recurs, they will be more
likely to recur… discomfort…
weakened. The greater the
satisfaction or discomfort, the greater
the strengthening or weakening of
the bond.”
Behaviorism split into two camps
Response is paired
with an outcome (appetitive or
aversive),
R-S*
Response increases
-Positive Reinforcement-app
-Negative Reinforcement-avs
Response decreases
-Punishment -avs
-Time-out/Diff Reinf Other -app
Learning theory today
Radical behaviorism - could only make
laws between behavior and environmental
events (only things that are observable)typified by Skinner
Learning theory today
Learning theory was more successful but
ultimately self-destructed by dozens of
wrong assumptions, most of which were
excessively simplistic
• equipotentiality of stimuli
• single associative value
• indepedence of path
• invariance of path
Animal Cognition
Learning theory - theories relating
environmental events and behavior could
have a limited number of inferred
processes & phenomena
e.g., association, generalization, etc.
• Survives primarily as a subdiscipline
of behavioral neuroscience
Cognitive Psychology emphasizes internal
mental representations and operations
between them, both it and computer
science are referred to as information
theory. Memory and knowledge are
cognitive terms.
• Strong integration of principles and
rigor into other fields of study
Edward Tolman
Tolman emphasized flexibility of animal
knowledge, in contrast to the very
mechanistic views of most behaviorists
Also rejected the idea of Tabula rasa
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Tolman & Tryon: Selective breeding of
maze bright and maze dull rats
Tolman's path integration
experiment
Influence of Rearing Environment
Cooper & Zubeck (1958) compare with
Rosenzweig & Tryon (1950)
Neuropsychology
Behavioral Neuroscience &
Neuropsychology
Enrichment first done
by D.O. Hebb (1949)
• Studies the breakdown of function after brain
damage in humans
• First original case of Lebourgne by Paul Broca
(1861), Broca’s language production area
(Wernicke-1894 - language reception)
Laws of equipotentiality
and mass action
Karl Lashley, father of
Behavioral Neuroscience
Strong push toward localization
of function
Early push was from Gall’s
Organology (Spurzheim’s Phrenology)
Read the critique by S.I. Franz
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Neuropsychology
Neuropsychology
-Reviewed cases of retrograde amnesia
associated with brain damage
--in most cases memory acquired remotely before
the insult was preserved compared to that
acquired recently
--Ribot’s law of regression - loss of memory is
inversely related to the time elapsed between the
event to be remembered and the injury. Ribot
concluded memories need a certain amount of
time to become organized and fixed.
Neuropsychology
Alois Alzheimer (1906)
Reported an institutionalized female patient with
progessive dementia. After being shown objects
and recognizing them, she immediately forgot
them and circumstances under which she learned
them. Both anterograde and retrograde amnesia
were present, and obeyed Ribot’s law as well.
Sergei Korsokoff (1887)
Memory impairment in chronic Alcoholics which
obeyed Ribot’s law.
Neuropsychology
Georg Muller & Alfons Pilzecker (1900)
- large number of experiments in normal subjects
-same as Ebbinghaus, but nonsense syllables in pairs
-Recall second item when probed with first from pairs
-Spontaneous recall of pairs from the same list
(perseveration) which had a time-gradient of a few
minutes -- speculated reflected transient brain activity
-Put distractor lists between training and recall, get
retroactive interference -- this follows a time gradient
so that distractors are only effective for a few minutes
Theodore Ribot (1882)
Several interesting case studies since then, but
the most influential was not until the 1950s.
Phenomenon of consolidation not studied a
whole lot by animal learning people until
recently
Phases of memory are a recurring theme which
we will struggle to understand throughout the
class.
--Concluded brain activity perseverates after new
learning and activity serves to consolidate memory.
Where are we today?
• Further than any other area of neuroscience
- not very far
• Strong stratification of the study of learning
and memory hinder vertical integration
• Try to build an interdisciplinary framework
from molecules to cognition
• No single engram identified at the moleculargenetic level
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