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Neurobiology of Learning and Memory

Stephan Anagnostaras

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My view on learning and memory

For this class:Field is broad and the breadth is important,so we will follow good examples to keepdepth

Several different fields cover learning andmemory. My view is there should be onefield and we would all be in the learningand memory building. Course will comefrom an eclectic perspective

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Several modern disciplines studyneurobiology of learning and memory

Psychology• Behavioral Neuroscience• Cognitive Neuroscience/Neuropsychology

Physiology• Synaptic Plasticity

Molecular Genetics• reverse, forward, and epigenetic approaches

Biology• Neuroethology of birdsong learning

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Learning and Memory

Why learning and memory?

Learning - current views on this term are from thefield of learning theory/behavioral psychology.A relatively permanent change in behavior as the result ofexperience - BF Skinner

Memory - current views from in informationprocessing theory (cognitive psychology andcomputer science).The capacity to store and retrieve of information (comp sci)The faculty of the mind by which it retains the knowledge ofprevious thoughts, impressions, or events. (cognitive psych)

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Learning versus Memory

Historically there was deep animosity betweenbehavioral & cognitive psychologists. Why?Problem relates to view of associationism.

Behaviorism - the cornerstone is behaviorbecause it is observable. Goal is to find lawfulrelationships between external events & behavior

Cognitive psychology - a key tenet is theconcept of an internal representation. This ishow knowledge is stored, and operations canoccur between representations. Can usually onlybe inferred or known through introspection.

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Origins of the study of L&M

• The study of learning is closely related to thebeginning of experimental psychology (around 1900)and, before that epistemology (philosophical study ofhow we have knowledge)

Nature-Nurture DebateRenee Descartes (1641)Nativism - knowledge is innatively given - e.g.,

knowledge of God, perfection, infinityRationalism - 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

Aristotle (350 BC) - 4 laws of memory1. Similarity2. Contrast3. Contiguity4. Frequency

John Locke (1690)Empiricism (Associationism) -knowledge is gained by experienceas provided to the mind by the senses.-these views advanced by others- esp David Hume in the 1700s-Enquiry concerning human understanding, 1748

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Origins of the study of memory

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 between20 min and 31 d

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Origins of the study of memory

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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 ofVerbal Learning and Verbal Behavior, 5, 351-60

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Serialpositioneffect isubiquitous

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Origins of the study of memory

William James (1890)• argued there must be at leasttwo types of memory

Primary memory-information currently contained in consciousness

Secondary memory-stored information which can be brought intoconsciousness

First of many suggestions that there were multiplememory systems.

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Origins of the study of memory

The study of memory developed into informationprocessing theory in the 1960s

* Multi-store Memory System* Sensory Memory* Short Term Memory* Long Term Memory

* Information Processing in Memory* Encoding* Storage* Retrieval

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Origins of the study of learningBehaviorists tended to be somewhat hostile andengaged in many turf battles

In the domain of clinical psychology they werebattling it out with the psychoanalytic approach.Very much against introspection, tended to becomeextreme in this domain, and rejected cognition aswell.

In the domain of animal behavior, they werebattling it out with the ethologists. Ethologistsbelieved everything was innate and nothing waslearned, hence behaviorists believed nothing wasinnate and everything learned.

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Behaviorist Tradition

Behaviorism focuses on objectively observable behaviorand discounts unobservable mental activities.

Behaviorists mostly studied animal and human learningfocusing on observable behavior and ways to changebehavior. Their studies of learning came to be knownas learning theory and their studies of how tochange behavior is known as behavior modification

• Largely relationships between external stimuli andevents and their ability to influence behavior

Radical behaviorism allows no intervening processes(e.g., BF Skinner) while other forms are more lenient.

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Behaviorism

John B Watson, thefather of AmericanBehaviorism

– Began a scientificmovement forPsychology, againstseveral mysticalsquishy fields, esp.FreudianPsychoanalysis

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Watson & Raynor's famous experiment with "Little Albert"

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Watson & Rayner's (1920) famous experiment with "Little Albert"

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Watson & Rayner's famous experiment with "Little Albert"

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Behaviorism of the time was very anti-genetics, in part because of the evil mental

testing movement

Give me a dozen healthy infants, well-formed, and my own specified worldto bring them up in and I'll guaranteeto take any one at random and trainhim to become any type of specialist Imight select--doctor, lawyer, artist,merchant- chief, and yes, evenbeggarman and thief, regardless ofhis talents, penchants, tendencies,abilities, vocations, and race of hisancestors - John Watson

Concept of "Tabula rasa" - organismsare born as blank slates

John Watson andRosalie Rayner

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Tabula rasa v. intelligence

• Notice our education system is still scarred bythe nature-nurture debate

• “Social scientists” who think everything isnurture

• Mental testers who think everything is nature

• As a result, very little study of genetics oflearning until 1992

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Russian Reflexology

Ivan Pavlov

CS CR

URUS CS

CS-US pairing

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Pavlov’s Little Albert

CR

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Learning and Performance

Distinction between learning/memory and performancean important problem in animal and human studies

Learning can only be inferred by performance:in humans, a response or a change in behaviorin rats, a change in behavior

• Performance may not occur:

Latent learning [Tolman & Honzik (1930)]Test anxiety

• Require extensive controls

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Operant/IntrumentalConditioning

Law of Effect (1911)“Of several responses made to thesame situation, those which areaccompanied by or closely followedby satisfaction to the animal will, allother things being equal, be morefirmly connected with the situation, sothat, when it recurs, they will be morelikely to recur… discomfort…weakened. The greater thesatisfaction or discomfort, the greaterthe strengthening or weakening ofthe bond.”

Edward Thorndike

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Operant/IntrumentalConditioning

Response is pairedwith an outcome (appetitive oraversive),R-S*

Response increases-Positive Reinforcement-app-Negative Reinforcement-avs

Response decreases-Punishment -avs-Time-out/Diff Reinf Other -app

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Behaviorism split into two camps

Learning theory - theories relatingenvironmental events and behavior couldhave a limited number of inferredprocesses & phenomena

e.g., association, generalization, etc.

Radical behaviorism - could only makelaws between behavior and environmentalevents (only things that are observable)-typified by Skinner

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Learning theory today

Learning theory was more successful butultimately self-destructed by dozens ofwrong assumptions, most of which wereexcessively simplistic

• equipotentiality of stimuli• single associative value• indepedence of path• invariance of path

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Learning theory today

• Survives primarily as a subdisciplineof behavioral neuroscience

• Strong integration of principles andrigor into other fields of study

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Animal Cognition

Edward Tolman

Cognitive Psychology emphasizes internalmental representations and operationsbetween them, both it and computerscience are referred to as informationtheory. Memory and knowledge arecognitive terms.

Tolman emphasized flexibility of animalknowledge, in contrast to the verymechanistic views of most behaviorists

Also rejected the idea of Tabula rasa

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Tolman's path integrationexperiment �

Tolman & Tryon: Selective breeding ofmaze bright and maze dull rats

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Influence of Rearing Environment

Cooper & Zubeck (1958) compare withRosenzweig & Tryon (1950)

Enrichment first doneby D.O. Hebb (1949)

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Behavioral Neuroscience &Neuropsychology

Karl Lashley, father ofBehavioral Neuroscience

Laws of equipotentialityand mass action

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Neuropsychology

• 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)

Strong push toward localizationof functionEarly push was from Gall’sOrganology (Spurzheim’s Phrenology)

Read the critique by S.I. Franz

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Neuropsychology

Theodore Ribot (1882)

-Reviewed cases of retrograde amnesiaassociated with brain damage

--in most cases memory acquired remotely beforethe insult was preserved compared to thatacquired recently

--Ribot’s law of regression - loss of memory isinversely related to the time elapsed between theevent to be remembered and the injury. Ribotconcluded memories need a certain amount oftime to become organized and fixed.

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Neuropsychology

Alois Alzheimer (1906)Reported an institutionalized female patient withprogessive dementia. After being shown objectsand recognizing them, she immediately forgotthem and circumstances under which she learnedthem. Both anterograde and retrograde amnesiawere present, and obeyed Ribot’s law as well.

Sergei Korsokoff (1887)Memory impairment in chronic Alcoholics whichobeyed Ribot’s law.

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NeuropsychologyGeorg 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 fewminutes -- speculated reflected transient brain activity

-Put distractor lists between training and recall, getretroactive interference -- this follows a time gradientso that distractors are only effective for a few minutes

--Concluded brain activity perseverates after newlearning and activity serves to consolidate memory.

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Neuropsychology

Several interesting case studies since then, butthe most influential was not until the 1950s.

Phenomenon of consolidation not studied awhole lot by animal learning people untilrecently

Phases of memory are a recurring theme whichwe will struggle to understand throughout theclass.

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Where are we today?

• Further than any other area of neuroscience- not very far

• Strong stratification of the study of learningand memory hinder vertical integration

• Try to build an interdisciplinary frameworkfrom molecules to cognition

• No single engram identified at the molecular-genetic level

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