Post on 17-Aug-2015
Memory and Its Mechanism
Chairperson
Dr. T. Kumanan MD., DPM, Professor
Dr. S. J. X. Sugadev MD., Assistant Professor
Slide 1
Presented byDr. A. M. Anusa
First Year PG
Prepared by Prof. Rooban T,
Oral & Maxillofacial Pathologist
Memory
Origin of word from Greek God - Mnemosyne
Slide 2
Introduction Neurobiology of memory
Identifying where and how different types of information are stored
Hypothesis by Hebb Memory results from synaptic
alterations Study of simple invertebrates
Synaptic alterations underlie memories (procedural)
Electrical stimulation of brain Experimentally produce measurable
synaptic alterations - dissect mechanisms
Slide 3
Procedural Learning Declarative and
procedural memories Nonassociative Learning
Habituation▪ Learning to ignore
stimulus that lacks meaning
Sensitization▪ Learning to intensify
response to stimuli
Slide 4
Procedural Learning
Associative Learning Classical Conditioning
Slide 5
Procedural Learning
Associative Learning (Cont’d) Classical Conditioning
▪ Associates a stimulus that evokes response- unconditional stimulus with second stimulus that does not evoke response- conditional stimulus
Instrumental Conditioning▪ Experiment by Edward Thorndike ▪ Complex neural circuits due to motivation
Slide 6
Simple Systems: Invertebrate Models of Learning
Experimental advantages in using invertebrate nervous systems Small nervous systems Large neurons Identifiable neurons Identifiable circuits Simple genetics
Slide 7
Simple Systems: Invertebrate Models of Learning
Nonassociative Learning in Aplysia
Slide 8
Simple Systems: Invertebrate Models of Learning
Nonassociative Learning in Aplysia (Cont’d) Habituation of the Gill-Withdrawal Reflex
Slide 9
Simple Systems: Invertebrate Models of Learning
Nonassociative Learning in Aplysia (Cont’d) Sensitization of the Gill-Withdrawal
Reflex
Slide 10
Simple Systems: Invertebrate Models of Learning
Associative Learning in Aplysia Classical
conditioning CS-US pairing
▪ Cellular level▪ Molecular level
Slide 11
Simple Systems: Invertebrate Models of Learning
The molecular basis for classical conditioning in Aplysia
Slide 12
Vertebrate Models of Learning
Neural basis of memory learned from invertebrate studies Learning and memory can result from
modifications of synaptic transmission Synaptic modifications can be triggered
by conversion of neural activity into intracellular second messengers
Memories can result from alterations in existing synaptic proteins
Slide 13
Vertebrate Models of Learning
Synaptic Plasticity in the Cerebellar Cortex Cerebellum: Important site for motor
learning Anatomy of the Cerebellar Cortex
▪ Features of Purkinje cells▪ Dendrites extend only into molecular layer▪ Cell axons synapse on deep cerebellar nuclei
neurons▪ GABA as a neurotransmitter
Slide 14
Vertebrate Models of Learning The structure of the cerebellar cortex
Slide 15
Vertebrate Models of Learning
Synaptic Plasticity in the Cerebellar Cortex Long-Term Depression in the Cerebellar
Cortex
Slide 16
Vertebrate Models of Learning
Synaptic Plasticity in the Cerebellar Cortex (Cont’d) Long-Term Depression in the Cerebellar
Cortex (Cont’d)▪ Cerebellar LTD and Classical Conditioning in
Aplysia▪ Similarity: Input-specific synaptic modification ▪ Dissimilarity: Site of convergence and nature of
synaptic changes
Slide 17
Vertebrate Models of Learning
Synaptic Plasticity in the Cerebellar Cortex (Cont’d) Mechanisms of cerebellar LTD
▪ Learning▪ Rise in [Ca2+]i and [Na+]i and the activation of protein
kinase C
▪ Memory▪ Internalized AMPA channels and depressed excitatory
postsynaptic currents
Slide 18
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus LTP and LTD
▪ Key to forming declarative memories in the brain
Bliss and Lomo▪ High frequency electrical stimulation of
excitatory pathway Anatomy of Hippocampus
▪ Brain slice preparation: Study of LTD and LTPSlide 19
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus (Cont’d) Anatomy of the Hippocampus
Slide 20
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus (Cont’d) Properties of LTP in CA1
Slide 21
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus (Cont’d) Mechanisms of LTP in
CA1▪ Glutamate receptors
mediate excitatory synaptic transmission▪ NMDARs and AMPARs
Slide 22
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus (Cont’d) Long-Term Depression in CA1
Slide 23
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus (Cont’d) BCM theory
▪ When the postsynaptic cell is weakly depolarized by other inputs: Active synapses undergo LTD instead of LTP
▪ Accounts for bidirectional synaptic changes (up or down)
Slide 24
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus (Cont’d) LTP, LTD, and Glutamate Receptor
Trafficking ▪ Stable synaptic transmission: AMPA receptors
are replaced maintaining the same number▪ LTD and LTP disrupt equilibrium▪ Bidirectional regulation of phosphorylation
Slide 25
Vertebrate Models of Learning
LTP, LTD, and Glutamate Receptor Trafficking (Cont’d)
Slide 26
Vertebrate Models of Learning
LTP, LTD, and Glutamate Receptor Trafficking (Cont’d)
Slide 27
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus (Cont’d) LTP, LTD, and Memory
▪ Tonegawa, Silva, and colleagues▪ Genetic “knockout” mice▪ Consequences of genetic deletions (e.g., CaMK11 subunit)
▪ Advances (temporal and spatial control)▪ Limitations of using genetic mutants to study
LTP/learning: secondary consequences
Slide 28
The Molecular Basis of Long-Term Memory
Phosphorylation as a long term mechanism: Problematic (transient and turnover rates)
Persistently Active Protein Kinases Phosphorylation
maintained: Kinases stay “on” ▪ CaMKII and LTP
▪ Molecular switch hypothesis
Slide 29
The Molecular Basis of Long-Term Memory
Protein Synthesis Requirement of long-term memory
▪ Synthesis of new protein Protein Synthesis and Memory
Consolidation ▪ Protein synthesis inhibitors
▪ Deficits in learning and memory
CREB and Memory▪ CREB: Cyclic AMP response element binding
protein
Slide 30
The Molecular Basis of Long-Term Memory
Protein Synthesis (Cont’d) Structural Plasticity and Memory
▪ Long-term memory associated with formation of new synapses
▪ Rat in complex environment: Shows increase in number of neuron synapses by about 25%
Slide 31
Concluding Remarks
Learning and memory Occur at synapses
Unique features of Ca2+
Critical for neurotransmitter secretion and muscle contraction, every form of synaptic plasticity
Charge-carrying ion plus a potent second messenger▪ Can couple electrical activity with long-term
changes in brain Slide 32
End of Presentation
Slide 33
Cognitive ProcessesPSY 334Chapter 6 – Human
Memory: Encoding and Storage
Ebbinghaus
First rigorous investigation of human memory – 1885.
Taught himself nonsense syllables DAX, BUP, LOC
Savings – the amount of time needed to relearn a list after it has already been learned and forgotten.
Forgetting function – most forgetting takes place right away.
Memory Models
Atkinson & Shiffrin – proposed a three-stage model including: Sensory store – if attended goes to STM Short-term memory (STM) – if rehearsed
goes to LTM Long-term memory (LTM)
No longer the current view of memory. Still presented in some books.
The Three-Stage Model
Environment Sensory storeShort-term
(working) memory Long-term memory
Responses
Executive control processes
Sensation/perception Attention
encoding
retrieval
Retention Times
Environment Sensory storeShort-term
(working) memory Long-term memory
encoding
retrieval
1-3 seconds 15-25 seconds 1 sec to a lifetime
Sensory Memory
Holds info when it first comes in. Allows a person to extract meaning
from an image or series of sounds. Sperling’s partial report procedure:
A display of three rows of letters is presented.
After it is taken away, a tone signals which row to report.
Subjects were able to report most letters.
Sperling’s Partial Report
A medium tone signals the subject to report the letters in this row
Sperling’s Results
Delay
Kinds of Sensory Stores
Iconic memory – visual Bright postexposure field wipes out
memory after 1 sec, dark after 5 sec. Echoic memory – auditory
Lasts up to 10 sec (measured by ERP) Located in the sensory cortexes.
Short Term Memory
The original idea is that when info in sensory memory is paid attention to, it moves into short term memory.
With rehearsal, it then moves into long term memory.
STM has limited capacity, called memory span. Miller’s magic number (7 ± 2) New info pushes out older info
(Shepard)
Shepard’s Results
Number of intervening items
Probability of recalling the target item
Criticisms of STM
Rate of forgetting seemed to be quicker than Ebbinghaus’s data, but is not really.
Amount of rehearsal appeared to be related to transfer to long-term memory. Later it was found that the kind of
rehearsal matters, not the amount. Passive rehearsal does little to achieve
long-term memory. Information may go directly to LTM.
Depth of Processing
Craik & Lockhart – proposed that it is not how long material is rehearsed but the depth of processing that matters.
Levels of processing demo.
Working Memory
Baddeley – in working memory speed of rehearsal determines memory span. Articulatory loop – stores whatever can be processed in a given amount of time. Word length effect: 4.5 one-syllable
words remembered compared to 2.6 long ones.
1.5 to 2 seconds material can be kept. Visuopatial sketchpad – rehearses
images. Central executive – controls other
systems.
Word-Lenth Determines Forgetting
Delayed Matching Task
Delayed Matching to Sample – monkey must recall where food was placed. Monkeys with lesion to frontal cortex
cannot remember food location. Human infants can’t do it until 1 year
old. Regions of frontal cortex fire only
during the delay – keeping location in mind. Different prefrontal regions are used to
remember different kinds of information.
Delayed Matching to Sample
Importance of Frontal Cortex
In primates, working memory is localized to the frontal cortex.
Delayed matching to sample task: Monkeys are shown food that is then
hidden. Later they are given a chance to locate
it. Monkeys with frontal lobe lesions
cannot do this task.
Activation
Activation – how available information is to memory: Probability of access – how likely you are
to remember something. Rate of access – how fast something can
be remembered. From moment to moment, items
differ in their degree of activation in memory.
Anderson’s ACT Model
ACT – Adaptive Control of Thought Moses Effect -- subjects shown the
words Bible, animal and flood should recall Noah but recall Moses instead. When given the word flood they think of
Mississippi or Johnstown but not Noah. Why? Recall is based on both
baseline and activation from associated concepts. Moses and Jesus have higher baselines.
The ACT Model
Factors Affecting Activation
How recently we have used the memory: Loftus – manipulated amount of delay 1.53 sec first time, then 1.21, 1.28, and
1.33 with 3 items intervening. How much we have practiced the
memory – how frequently it is used. Anderson’s study (sailor is in the park)
Spreading Activation
Activation spreads along the paths of a propositional network. Related items are faster to recall.
Associative priming – involuntary spread of activation to associated items in memory. Kaplan’s dissertation – cues to solving
riddles hidden in the environment led to faster solutions.
Associative Priming
Meyer & Schvaneveldt – spreading activation affects how quickly words are read. Subjects judged whether pairs of related
& unrelated items were words. Judgments about related words were
faster.
Meyer and Schvaneveldt
Practice and Strength
The amount of spreading activation depends on the strength of a memory.
Memory strength increases with practice.
Greater memory strength increases the likelihood of recall.
Power Function
Each time we use a memory trace, it gradually becomes a little stronger.
Power law of learning: T = 1.40 P-0.24
T is recognition time, P is days of practice.
Linear when plotted on log-log scale.
Learning Curves
Practicing Addition Problems
Long Term Potentiation (LTP)
Neural changes may occur with practice: Long-term potentiation (LTP) in
hippocampus. Repeated electrical stimulation of
neurons leads to increased sensitivity. LTP changes are a power function.
Neural Changes Mirror Behavioral Changes
Neural Correlates of Encoding
Better memory occurs for items with stronger brain processing at the time of study: Words evoking higher ERP signals are
better remembered later. Greater frontal activation with deeper
processing of verbal information. Greater activation of hippocampus with
better long-term memory.
Activation in Prefrontal Cortex
Words activate left prefrontal cortex
Pictures activate right prefrontal cortex
Hemodynamic = blow flow during brain activity
Factors Influencing Memory
Study alone does not improve memory – what matters is how studying is done. Shallow study results in little
improvement. Semantic associates (tulip-flower) better
remembered than rhymes (tower-flower), 81% vs 70%.
Better retention occurs for more meaningful elaboration.
Elaborative Processing
Elaboration – embellishing an item with additional information.
Anderson & Bower – subjects added details to simple sentences: 57% recall without elaboration 72% recall with made-up details added
Self-generated elaborations are better than experimenter-generated ones.
Self-Generated Elaborations
Stein & Bransford – subjects were given 10 sentences. Four conditions: Just the sentences alone – 4.2 adjectives Subject generates an elaboration – 5.8 Experimenter-generated imprecise
elaboration – 2.2 Experimenter-generated precise
elaboration – 7.8 Precision of detail (constraint)
matters, not who generates the elaboration.
Advance Organizers
PQ4R method – use questions to guide reading. 64% correct, compared to 57% (controls) 76% of relevant questions correct, 52%
of non-relevant. These study techniques work
because they encourage elaboration. Question making and question
answering both improve memory for text (reviewing is better than seeing the questions first).
Meaningful Elaboration
Elaboration need not be meaningful – other sorts of elaboration also work.
Kolers compared memory for right-side-up sentences with upside-down. Extra processing needed to read upside
down may enhance memory. Slamecka & Graf – compared
generation of synonyms and rhymes. Both improved memory, but synonyms did more.
Slamecka & Graf’s Results
Mnemonics
Method of Loci – place items in a location, then take a mental walk.
Peg-word System – use peg words as a structure and associate a list of items with them using visualization. Create acronyms for lists of items.
Convert nonsense syllables (DAX, GIB) into meaningful items by associating them with real words (e.g., DAD).
“This Old Man” Song
http://www.youtube.com/watch?v=3cYf9vkW_xU
http://www.totlol.com/watch/5d-6Q5V79CM/This-Old-Man/0/
Pegword System
1 – bun2 – shoe3 – tree4 – door5 – hive6 – sticks7 – heaven8 – gate9 – wine10 -- hen
Incidental Learning
It does not matter whether people intend to learn something or not. What matters is how material is
processed. Orienting tasks:
Count whether work has e or g. Rate the pleasantness of words. Half of subjects told they would be asked
to remember words later, half not told. No advantage to knowing ahead of
time.
Awareness of Learning
Flashbulb Memories
Self-reference effect -- people have better memory for events that are important to them and close friends.
Flashbulb memories – recall of traumatic events long after the fact. Seem vivid but can be very inaccurate.
Thatcher’s resignation: 60% memory for UK subjects, 20% non-
UK
Self-Reference Effect
Two explanations: People have special mechanisms for
encoding info relevant to themselves. Info relevant to the self is rehearsed
more often. High arousal may enhance memory. Memory is better for words related to
the self – perhaps due to better elaboration.
PSYCHOLOGY 110-02General Psychology
University of Southern Mississippi Department of Psychology
Dr. David J. Echevarria, PhD Spring 2008
david.echevarria@usm.edu www.usm.edu/neurolab
Chapter 7 Memory
Chapter 7: Human Memory
Minute quiz…
Chapter 6 is on learningChapter 7 is on memory
How is memory related to learning???
Without memory learning is useless!
Think about all the times in one day you rely on your memory:
When is my next class? Did I pay my rent? Where did I park my car? When is my boy/girl friend’s
birthday? Performance on exams
How are memories stored?
Tip of the tongue
Did you ever say, “I can’t remember” only to actually “remember” later on?
How easily are they accessed?
What can interfere with memory?
What’s the capacity of short-term memory?
Memory span: Number of items that can be recalled from short-term memory, in order, on half of the tested memory trials It’s about 7 plus or minus 2 items
Not absolute; also depends on: How quickly items can be rehearsed Chunking
▪ Rearranging incoming information into meaningful or familiar patterns
The Working Memory Model Several distinct mechanisms:
Phonological loop: Like the inner voice; stores word sounds
Visuospatial sketchpad: Stores visual and spatial information
Central executive: Determines which mechanism to use, coordinates among them
Brain damage can selectively affect a single mechanism
Human Memory: Basic Questions
How does information get into memory? How is information maintained in
memory? How is information pulled back out of
memory?
Figure 7.2 Three key processes in memory
Encoding: Getting Information Into Memory
The role of attention Focusing awareness Selective attention = selection of input
Filtering: early or late?
Figure 7.3 Models of selective attention
Levels of Processing:Craik and Lockhart (1972)
Incoming information processed at different levels
Deeper processing = longer lasting memory codes
Encoding levels: Structural = shallow Phonemic = intermediate Semantic = deep
Figure 7.4 Levels-of-processing theory
Above is a scanpath of one reader over a broadsheet newspaper spread. The reader turned pages in her own pace, and read the entire newspaper. This is quite typical data. The texts are read no deeper than 40 % of their lengths. Very short looks on photos and long looks on information graphics.
http://www.sol.lu.se/humlab/eyetracking/
Scanning a Scene
Figure 7.5 Retention at three levels of processing
Enriching Encoding: Improving Memory
Elaboration = linking a stimulus to other information at the time of encoding Thinking of examples
Visual Imagery = creation of visual images to represent words to be remembered Easier for concrete objects: Dual-coding
theory Self-Referent Encoding
Making information personally meaningful
Storage: Maintaining Information in Memory
Analogy: information storage in computers ~ information storage in human memory
Information-processing theories Subdivide memory into 3 different stores
▪ Sensory, Short-term, Long-term
Figure 7.7 The Atkinson and Schiffrin model of memory storage
Sensory Memory
Brief preservation of information in original sensory form
Auditory/Visual – approximately ¼ second George Sperling (1960)
▪ Classic experiment on visual sensory store
Figure 7.8 Sperling’s (1960) study of sensory memory
Short Term Memory (STM)
Limited capacity – magical number 7 plus or minus 2 Chunking – grouping familiar stimuli
for storage as a single unitLimited duration – about 20
seconds without rehearsal Rehearsal – the process of repetitively
verbalizing or thinking about the information
Figure 7.9 Peterson and Peterson’s (1959) study of short-term memory
Short-Term Memory as “Working Memory”
STM not limited to phonemic encoding Loss of information not only due to
decay Baddeley (1986) – 3 components of
working memory Phonological rehearsal loop Visuospatial sketchpad Executive control system
Long-Term Memory: Unlimited Capacity
Permanent storage? Flashbulb memories Recall through hypnosis
Debate: are STM and LTM really different? Phonemic vs. Semantic encoding Decay vs. Interference based
forgetting
How is Knowledge Representedand Organized in Memory?
Clustering and Conceptual Hierarchies Schemas and Scripts Semantic Networks Connectionist Networks and PDP Models
Retrieval: Getting InformationOut of Memory
The tip-of-the-tongue phenomenon – a failure in retrieval Retrieval cues
Recalling an event Context cues
Reconstructing memories Misinformation effect
▪ Source monitoring, reality monitoring
Forgetting: When Memory Lapses
Retention – the proportion of material retained Recall Recognition Relearning
Ebbinghaus’s Forgetting Curve
Figure 7.16 Ebbinghaus’ forgetting curve for nonsense syllables
Figure 7.17 Recognition versus recall in the measurement of retention
Why Do We Forget?
Ineffective EncodingDecay theory Interference theory
Proactive Retroactive
Figure 7.19 Retroactive and proactive interference
Figure 7.20 Estimates of the prevalence of childhood physical and sexual abuse
Retrieval Failure
Encoding Specificity Transfer-Appropriate Processing Repression
Authenticity of repressed memories? Memory illusions Controversy
Figure 7.22 The prevalence of false memories observed by Roediger and McDermott (1995)
The Physiology of Memory
Biochemistry Alteration in synaptic transmission
▪ Hormones modulating neurotransmitter systems
▪ Protein synthesisNeural circuitry
Localized neural circuits▪ Reusable pathways in the brain▪ Long-term potentiation
The Physiology of Memory
Anatomy Anterograde and Retrograde Amnesia
▪ Cerebral cortex, Prefrontal cortex, Hippocampus,
▪ Dentate gyrus, Amygdala, Cerebellum
Figure 7.23 The anatomy of memory
Figure 7.25 Retrograde versus anterograde amnesia
Are There Multiple Memory Systems?
Declarative vs. Procedural Semantic vs. Episodic Prospective vs. Retrospective
Figure 7.26 Theories of independent memory systems
Improving Everyday Memory
Engage in adequate rehearsal Distribute practice and minimize
interference Emphasize deep processing and
transfer-appropriate processing Organize information Use verbal mnemonics Use visual mnemonics
Neuroscience: Exploring the Brain, 3e
Chapter 25: Molecular Mechanisms of Learning and Memory
Introduction
Neurobiology of memory Identifying where and how different types
of information are stored Hebb
Memory results from synaptic modification Study of simple invertebrates
Synaptic alterations underlie memories (procedural)
Electrical stimulation of brain Experimentally produce measurable
synaptic alterations - dissect mechanisms
Procedural Learning
Procedural memories amenable to investigation
Nonassociative Learning Habituation
▪ Learning to ignore stimulus that lacks meaning
Sensitization▪ Learning to intensify
response to stimuli
Procedural Learning Associative Learning
Classical Conditioning: Pair an unconditional stimulus (UC) with a conditional stimulus (CS) to get a conditioned response (CR)
Procedural Learning Associative Learning (Cont’d)
Instrumental Conditioning▪ Learn to associate a response with a
meaningful stimulus, e.g., reward lever pressing for food
▪ Complex neural circuits related to role played by motivation
Simple Systems: Invertebrate Models of Learning
Experimental advantages in using invertebrate nervous systems Small nervous systems Large neurons Identifiable neurons Identifiable circuits Simple genetics
Simple Systems: Invertebrate Models of Learning
Nonassociative Learning in Aplysia Gill-withdrawal reflex Habituation
Simple Systems: Invertebrate Models of Learning
Nonassociative Learning in Aplysia (Cont’d) Habituation results from presynaptic modification at L7
Simple Systems: Invertebrate Models of Learning
Nonassociative Learning in Aplysia (Cont’d) Repeated electrical stimulation of a sensory neuron leads to
a progressively smaller EPSP in the postsynaptic motor neuron
Simple Systems: Invertebrate Models of Learning
Nonassociative Learning in Aplysia (Cont’d) Sensitization of the Gill-Withdrawal Reflex involves L29
axoaxonic synapse
Simple Systems: Invertebrate Models of Learning
Nonassociative Learning in Aplysia (Cont’d) 5-HT released by L29 in
response to head shock leads to G-protein coupled activation of adenylyl cyclase in sensory axon terminal.
Cyclic AMP production activates protein kinase A.
Phosphate groups attach to a potassium channel, causing it to close
Simple Systems: Invertebrate Models of Learning
Nonassociative Learning in Aplysia (Cont’d) Effect of decreased
potassium conductance in sensory axon terminal
More calcium ions admitted into terminal and more transmitter release
Simple Systems: Invertebrate Models of Learning
Associative Learning in Aplysia Classical conditioning: CS
initially produces no response but after pairing with US, causes withdrawal
Simple Systems: Invertebrate Models of Learning
• The molecular basis for classical conditioning in Aplysia– Pairing CS and US causes greater activation of adenylyl cyclase
because CS admits Ca2+ into the presynaptic terminal
Vertebrate Models of Learning Neural basis of memory: principles
learned from invertebrate studies Learning and memory can result from
modifications of synaptic transmission Synaptic modifications can be triggered
by conversion of neural activity into intracellular second messengers
Memories can result from alterations in existing synaptic proteins
Vertebrate Models of Learning Synaptic Plasticity in the Cerebellar
Cortex Cerebellum: Important site for motor
learning Anatomy of the Cerebellar Cortex
▪ Features of Purkinje cells▪ Dendrites extend only into molecular layer▪ Cell axons synapse on deep cerebellar nuclei
neurons▪ GABA as a neurotransmitter
Vertebrate Models of Learning The structure of the cerebellar cortex
Vertebrate Models of Learning
• Cancellation of expected reafference in the electrosensory cerebellum of skates- synaptic plasticity at parallel fiber synapses.
Vertebrate Models of Learning
Synaptic Plasticity in the Cerebellar Cortex Long-Term Depression in the Cerebellar
Cortex
Vertebrate Models of Learning Synaptic Plasticity in the Cerebellar
Cortex (Cont’d) Mechanisms of cerebellar LTD
▪ Learning▪ Rise in [Ca2+]i and [Na+]i and the activation of protein
kinase C
▪ Memory▪ Internalized AMPA channels and depressed excitatory
postsynaptic currents
Vertebrate Models of Learning
Synaptic Plasticity in the Cerebellar Cortex (Cont’d)
Vertebrate Models of Learning
Synaptic Plasticity in the Cerebellar Cortex (Cont’d)
Vertebrate Models of Learning Synaptic Plasticity in the Hippocampus
LTP and LTD▪ Key to forming declarative memories in the brain
Bliss and Lomo▪ High frequency electrical stimulation of excitatory
pathway Anatomy of Hippocampus
▪ Brain slice preparation: Study of LTD and LTP
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus (Cont’d) Anatomy of the Hippocampus
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus (Cont’d) Properties of LTP in CA1
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus (Cont’d) Mechanisms of LTP in CA1
▪ Glutamate receptors mediate excitatory synaptic transmission▪ NMDA receptors and
AMPA receptors
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus (Cont’d) Long-Term Depression in CA1
Vertebrate Models of Learning
Synaptic Plasticity in the Hippocampus (Cont’d) BCM theory
▪ When the postsynaptic cell is weakly depolarized by other inputs: Active synapses undergo LTD instead of LTP
▪ Accounts for bidirectional synaptic changes (up or down)
Vertebrate Models of Learning Synaptic Plasticity in the
Hippocampus (Cont’d) LTP, LTD, and Glutamate Receptor
Trafficking ▪ Stable synaptic transmission: AMPA receptors
are replaced maintaining the same number▪ LTD and LTP disrupt equilibrium▪ Bidirectional regulation of phosphorylation
Vertebrate Models of Learning LTP, LTD, and Glutamate Receptor
Trafficking (Cont’d)
Vertebrate Models of Learning
LTP, LTD, and Glutamate Receptor Trafficking (Cont’d)
Vertebrate Models of Learning Synaptic Plasticity in the Hippocampus (Cont’d)
LTP, LTD, and Memory▪ Tonegawa, Silva, and colleagues
▪ Genetic “knockout” mice▪ Consequences of genetic deletions (e.g., CaMK11
subunit)▪ Advances (temporal and spatial control)
▪ Limitations of using genetic mutants to study LTP/learning: secondary consequences
The Molecular Basis of Long-Term Memory
Phosphorylation as a long term mechanism:Persistently Active Protein Kinases Phosphorylation maintained:
Kinases stay “on” ▪ CaMKII and LTP
▪ Molecular switch hypothesis
The Molecular Basis of Long-Term Memory
Protein Synthesis Protein synthesis required for formation of
long-term memory▪ Protein synthesis inhibitors
▪ Deficits in learning and memory
CREB and Memory▪ CREB: Cyclic AMP response element binding
protein
The Molecular Basis of Long-Term Memory Protein Synthesis (Cont’d)
Structural Plasticity and Memory▪ Long-term memory associated with
transcription and formation of new synapses▪ Rat in complex environment: Shows increase
in number of neuron synapses by about 25%
Concluding Remarks Learning and memory
Occur at synapses Unique features of Ca2+
Critical for neurotransmitter secretion and muscle contraction, every form of synaptic plasticity
Charge-carrying ion plus a potent second messenger▪ Can couple electrical activity with long-term
changes in brain
End of Presentation
Simple Systems: Invertebrate Models of Learning
The molecular basis for classical conditioning in Aplysia Pairing CS and US causes greater activation of
adenylyl cyclase because CS admits Ca2+ into the presynaptic terminal
Simple Systems: Invertebrate Models of Learning
Associative Learning in Aplysia Classical conditioning: CS initially produces no response
but after pairing with US, causes withdrawal
Vertebrate Models of Learning
Synaptic Plasticity in Human area IT
LECTURE 20-21: CELLULAR BASIS OF LEARNING & MEMORY
REQUIRED READING: Kandel text, Chapter 63, and Assigned Review Articles
Research on cellular basis of learning & memory mainly performed in three animal systems
Aplysia Drosophila Mouse
All neurons and synapsesin behavioral circuits areidentified and can be recorded easily
Ideal for detailing mechanisms underlying implicit learned motor responses
Capable of learned behaviors
Amenable to randommutagenesis andselection of mutantswith defectivebehaviors
Similar anatomy to human
Amenable to study ofexplicit memory
Hippocampus amenableto electrophysiology
Behavior modification ofgenetically modified mice
APLYSIA SHORT-TERM LEARNED RESPONSES AFFECTING GILL WITHDRAWL REFLEX
HABITUATION SENSITIZATION CLASSICALCONDITIONING
Repeated tactile stimulation of siphon depressesgill withdrawl response
Harmful stimulussensitizesgill withdrawl responseto subsequentharmful OR harmlessstimuli given tosame OR differentbody regions
Pairing harmful stimuluswith preceding harmless conditioning stimulus sensitizesgill withdrawl responseto subsequentconditioning stimulusbut not to tactile stimuligiven to other body areas
HABITUATION IS DUE TO DEPRESSED NEUROTRANSMITTER RELEASE AT SEVERAL SITES
Rapidly repeated tactile stimulation of siphonattenuates gill withdrawl both during thetraining and for a short period afterwards.
Habituation is due to reducedneurotransmitter release by thesensory neuron and by relevant interneuronsin response to the tactile stimulus.I.e., the memory of habituationis distributed at various synapsesin the circuit
Whereas a rapid series of stimuli inducesshort-term habituation,several sets of tactile stimuli distributedover several hours induceslong-term habituation that lasts for weeks.
Long-term habituation requiresnew protein synthesis and is due to pruning of synaptic connections
SHORT-TERM SENSITIZATION IS MEDIATED THROUGH AXO-AXONICSEROTONERGIC SYNAPSES OF FACILITATING INTERNEURONS
Serotonergic facilitating interneuronssend axo-axonic connections tobroadly distributed sensory neurons
Unconditioned stimulus causes interneurons to release serotonin,which acts through metabotropicHT receptors to increase thelikelihood of neurotransmitter releasefollowing sensory neuron firing
Sensitization can be mimicked withoutsensitizing stimulus by local experimental application of serotonin
Sensitization is mediated bypresynaptic elevation of cAMP & PKA activity,which has three effects:
1) Greater proportion of vesicles in active zone(synapsin phosphorylation?)
2) K+ channel inactivation increases duration of depolarization andmagnitude of Ca+2 influx
3) Activation of L--type calcium channels
CLASSICAL CONDITIONING EMPLOYS SEQUENCE-REINFORCED PRODUCTION OF cAMP
Conditioning is only effective when CS precedes US by a short interval (~ 0.5 sec)
CS elevates calcium in presynaptic terminal at moment of US.Calcium/CAM enhances the enzymatic activity of adenylate cyclase triggered by 5-HT.
Adenylate cyclase is a biochemical “coincidence detector”
TEMPORALLY SPACED SENSITIZATION OR CONDITIONING TRAININGSINDUCE LONG-TERM IMPLICIT MEMORY
Long-term sensitization
and conditioning arealso mediated through presynaptic cAMP
productionand PKA activity
PKA induces specific CREB-dependentgene transcription and protein synthesis:
Newly synthesized ubiquitin
hydrolase degrades PKA regulatory
subunits, making the enzymeconstitutively active
Other newly synthesized
proteins help build new
presynaptic terminalsonto motor neurons
GENETIC SCREENS FOR GENES AFFECTING CONDITIONING IMPLICIT MEMORYALL AFFECT THE cAMP-PKA-CREB PATHWAY
FLY MUTANTS SELECTED FOR DEFECTS IN IMPLICIT MEMORY
DUNCE encodes cAMP phosphodiesterase
RUTABAGA mutant defective for Ca+2/CAM enhancement of cyclase
AMNESIAC encodes a peptide neurotransmitter acting on GS-coupled receptor
PKA-R1 encodes PKA
HIPPOCAMPAL NEURONS IN DIFFERENT RELAYS ARE ALLCAPABLE OF UNDERGOING SYNAPTIC LONG-TERM POTENTIATION
AXON STIMULATION PROTOCOL AMPLITUDE OF EPSCS
20 min1 m 60 minOnce
per
min
ute
Once p
er m
inute
10 Hz
EP
SP
Slo
pe
(% o
rig
inal
)300
100
200
TIME (min)6020 40 80“THETA” BURST
One Theta burst gives what is sometimes calledEarly LTP, which is less than doublingof EPSC which lasts for hours
Four Theta bursts spaced minutes apart generateLate LTP, with up to 4-fold EPSC stimulationthat lasts for days
INDUCTION AND EXPRESSION OF SYNAPTIC PLASTICITY
Prior synaptic activity can INDUCE long-term plasticity. Such plasticity can be INDUCED by molecular events occuring either presynaptically or postsynaptically.
The changes in transmission following synaptic plasticity can be EXPRESSED either presynaptically and/or postsynaptically, and need not correspond to the site of INDUCTION.
E.g., at a certain synapse, postsynaptic calcium influx can INDUCE plasticity which is then EXPRESSED as changes in presynaptic neurotransmitter release probability.
LTP AT MOSSY FIBER--CA3 SYNAPSES IS DUE TO PRESYNAPTIC CALCIUM INFLUXAND cAMP/PKA PATHWAY
LTP AT SCHAFFER COLLATERAL--CA1 SYNAPSES IS DUE TO POSTSYNAPTIC CALCIUM INFLUX AND CAM KINASE ACTIVITY
LTP at CA3-CA1 synapse is blocked byNMDAR antagonist APV and by inhibitorsof CAM kinase
PRESYNAPTIC COMPONENT OF EARLY AND LATE LTP AT CA3--CA1 SYNAPSES RESEMBLES SHORT- AND LONG-TERM SENSITIZATION
Late LTPabsolutely requiresnew protein synthesis
PRESYNAPTIC COMPONENT OF EARLY AND LATE LTP REQUIRES POSTSYNAPTIC CAMK ACTIVITY AND RETROGRADE SIGNALS
OTHER MECHANISMS OF PLASTICITY ENHANCING EPSPS
LTP can be expressed postsynaptically as a reduction of leak conductance in dendritic spine. This enables the EPSC to generate EPSP with greater length and time constants.
Excitatory transmission can be enhanced by HETEROSYNAPTIC INHIBITION OF INHIBITORY TRANSMISSION. This is mediated by endogenous cannabinoids acting on presynpatic terminals of nearby GABAergic synapses.
IS LTP REQUIRED FOR HIPPOCAMPAL CONSOLIDATION OF EXPLICIT MEMORY?CAMK AND NMDAR1 NEEDED FOR LONG-TERM SPATIAL REPRESENTATION IN HIPPOCAMPUS
Single pyramidal neuronin hippocampusfires when mouse is incertain location(independent ofanimal’s orientation)
Normal mouse remembers where it has been.spatial map in HCdoes not change insubsequent chamber trials
Mice with hippocampus-restricted mutationsin CAMK or NMDAR1establish place fields,but do not rememberfrom day to day
IS LTP REQUIRED FOR HIPPOCAMPAL CONSOLIDATION OF EXPLICIT MEMORY?HIPPOCAMPAL CAMK AND NMDAR1 NEEDED FOR BOTH LTP AND SPATIAL MEMORY
SYNAPSES SENSITIVE TO NMDAR-MEDIATED LTP ARE ALSO SENSITIVETO NMDAR-MEDIATED LONG-TERM DEPRESSION (LTD)
AXON STIMULATION PROTOCOL AMPLITUDE OF EPSCS
20 min1 m 60 minOnce
per
min
ute
Once p
er m
inute
10 Hz
EP
SP
Slo
pe
(% o
rig
inal
)
300
100
200
TIME (min)6020 40 80
LTP
20 min5 m 60 minOnce
per
min
ute
Once p
er m
inute
2 Hz
EP
SP
Slo
pe
(% o
rig
inal
)300
100
200
TIME (min)6020 40 80
LTD
LTD HAS A LOWER CALCIUM CONCENTRATION THRESHOLD THAN LTP,BUT LTP IS DOMINANT
LOW-FREQUENCY STIMULUS TRAIN
LOW-LEVEL CALCIUM ENTRY
ACTIVATION OF CALCINEURIN
AMPA RECEPTOR INTERNALIZATION
LTD
THETA- OR HIGH-FREQUENCY STIMULUS TRAIN
GREATER CALCIUM ENTRY
ACTIVATION OF CALCINEURIN AND CAMK
AMPA RECEPTOR INSERTION AND PHOSPHORYLATION
LTP
STRUCTURAL AND FUNCTIONAL FEATURES OF AMPA-TYPE GLUTAMATE RECEPTORS
AMPA receptors are homo- or hetero-tetramersRestriction of calcium entry mediated by GluR2; tetramers containing >1 GluR2 subunit conduct only Na+/K+
AMPA receptors encoded by different genes or by alternative splicing have different C-terminal tails.Receptor tails contain phosphorylation sites for different protein kinases and binding sitesfor PDZ-domain-containing proteins
Receptors containing only GluR2(short) and/or GluR3 subunits are delivered constitutively fromvesicles to synapseRetention at synapse mediated by complex with Glutamate Receptor Interacting Protein (GRIP)
Receptors containing at least one GluR1(long) subunit are stored in intracellular vesicles near synapseDuring LTP, GluR1-containing tetramers are added to the synapse
NMDAR-INDUCED CAMK ACTIVITY ACTS ON AMPA RECEPTORS IN TWO WAYSTO PROMOTE LTP
CAMKPDZ-protein
STGGRIPPSD-95
GRIPPSD-95
Calcineurin
CAMK phosphorylates an unknownprotein, enabling a PDZ-proteinthat interacts with long tailon GluR1 to deliver receptorTO EXTRASYNAPTIC SITE
Delivered receptors migrate (randomly?)into post-synaptic density,where interactions of receptor-associated GRIP and STG and themajor postsynaptic matrix proteinPSD-95 anchor receptor to synapse
Newly delivered GluR1-containingAMPA receptors can be phosphorylateddirectly by CAMK, whichincreases unitary conductanceof the receptor
Calcineurin activation promotes internalizationof AMPA receptors containing onlyshort-tail subunits, thereby promoting LTD
WHEN HIGH CALCIUM ENTRY ACTIVATES BOTH CALCINEURIN AND CAMK,CAMK-MEDIATED GluR1-CONTAINING AMPAR EXOCYTOSIS EXCEEDS CALCINEURIN-MEDIATEDSHORT TAIL-ONLY AMPAR ENDOCYTOSIS
HIGH CAMK ACTIVITY INDUCED DURING LATE LTP IS ALSO MEDIATED BYNEW CAM KINASE PROTEIN SYNTHESIS NEAR THE SYNAPSE
Most mRNAs have 3’ polyA tail, which is necessary for initiation of the mRNA’s translation
Neurons contain some mRNAs that are not polyadenylated, are not translated,and are transported along dendrites to areas near dendritic spines
NMDA receptor activation and calcium entry activates a protein kinasecalled AURORA
Aurora kinase activates translation of nearby dormant mRNAs
ONE OF THESE DORMANT RNAs ENCODES CAM KINASE
Because of its dendritic localizaation, new CAMK synthesis is restricted to the synapse undergoing LTP
The dendritic localization of dormant CAMK RNA and its activation during LTP are mediated byCytoplasmic Polyadenylation Element Binding (CPEB) protein
HOW DOES CPEB PROTEIN CONTROL RNA DORMANCY AND ACTIVATION IN NEURONS?
PolyA is needed for assembly of 5’translation initiation complex
CPEB protein binding to 3’ CPEhelps mask RNA 5’ end
CPEB phosphorylation by Aurora allows for recruitment of polyA polyermerase (PAP)
Polyadenylation of dormant RNA allows assembly of 5’ translation initiation complex
Memory DisordersPsychology 3717
Introduction
The strange case of Charles D’Sousa
Or is it Philip Cutajar?
Rare type of disorder
Some stuff clearly spared
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Introduction
Results with amnesiacs has lead to many discoveries about memory Episodic vs. semantic memory Procedural vs. declarative memory Implicit vs. explicit memory Phonological loop vs. visuo spatial
sketchpad
problems
Taxonomy Individual differences Interpretation Application Mostly comes down to a lack of
control, which of course is inevitable
Case studies
We pretty much have to rely on these
They are, thankfully, rare Usually some sort of accident or a
stroke
Case SP
Stroke patient Both Medial temporal lobes, left Hp
and lots of surrounding area, but not the amygdala
Had trouble naming objects Anterograde and retrograde amnesia Similar to KC
Clive Wearing
Case of encephalitis Pervasive amnesia Both semantic and
episodic impairment Temporal lobe
dilation Hp destroyed
QuickTime™ and aTIFF (Uncompressed) decompressor
are needed to see this picture.
Performance Patterns
Retrograde amnesia Losing past memories
Anterograde amnesia No new memories
Spared function Often implicit tasks, such as priming or
ability to learn a new skill
Typically spared
Working Memory Semantic memory
Even KC could learn new stuff Declarative information using
Tulving’s method Restrict errors
Why?
Difficulties in interference, retrieval and encoding
Consolidation Tends to come down to something to do
with HP Context or sending item off for
processing or some such thing
Semantic memory problems
What is a cat? Temporal lobe problems Oddly enough, episodic memory
often intact in these rare cases
Working Memory Problems
There are cases of people with intact phonological loops and visuo spatial sketchpads that are pretty much toast
And vice versa
Alzheimer’s More than half of all
dementia is from AD 2 times more
women than men Could be because
women live longer though
dementia and brain stuff Neurofibrillary tangles
and neuritic plaques
AD
MASSIVE cell death In essence, you get like lesions
everywhere ‘cortical’ dementia, but you get
these lesions, holes really, everywhere
Neurotransmitters affected
ACh is important in memory, especially in HP
The ACh system is severely damaged in AD
Indeed it is almost targeted Other systems too though
Memory effects
Episodic effects Eventually semantic effects Retrieval cues don’t help
Information was not even encoded Nondeclarative stuff, skills etc, are
the last to go
Treatment
Most drugs target the cholinergic system
This disease not only affects the victim, but also his/her family
NGF is promising Treatments will come, but, reversal, I
dunno Respite care is key for the family
Conclusions
Frankly there is not a great deal of hope for most amnesiacs
That said, neuroscience is moving pretty fast
Has helped us understand normal function
The information-processing model of human memory
Relations between iconic memory, short-term memory and long-term memory
Logie’s (1995) drawing of the components of working memory
Source: Adapted from Logie, R., Visual Spatial Working Memory, p. 127. © 1995. Reprinted by permission of Psychology Press Limited, Hove, UK.
The articulatory loop
The limits of short-term and working memory
Source: (a) Adapted from Peterson, L.M. and Peterson, J.M., Short-term retention of individual verbal items. Journal of Experimental Psychology, 1959, 58, 193–198., (b) Adapted from Waugh, N.C. and Norman, D.A., Primary memory. Psychological Review, 1965, 72, 89–104.
Shallow versus deep processing
Source: Based on Craik, F.I.M. and Lockhart, R.S., Levels of processing: A framework for memory research. Journal of Verbal Behavior, 1972, 11, 671–684.
Explicit versus implicit memory
Source: Based on data from Graf, P. and Mandler, G., Activation makes words more accessible, but not necessarily more retrievable. Journal of Verbal Learning and Verbal Behavior, 1984, 23, 553–568.
The Stroop effect
Ebbinghaus’s forgetting curve
Source: Adapted from Ebbinghaus, H., Memory: A contribution to experimental psychology (H.A. Ruger and C.E. Bussenius, trans.), 1885/1913. Teacher’s College Press, Columbia University, New York.
Eyewitness testimony
Source: Based on data from Loftus, E.F. and Palmer, J.C., Reconstruction of automobile destruction: An example of the interaction between language and memory. Journal of Verbal Learning and Verbal Behavior, 1974, 13, 585–589.
Retroactive and proactive interference
Explicit and implicit memory of amnesic and non-amnesic individuals
Source: Adapted from Graf, P., Squire, L.R. and Mandler, G., The information that amnesic patients do not forget. Journal of Experimental Psychology: Learning, memory and cognition, 1984, 10, 164–178.
The effect of hippocampal damage on a
rat’s navigational ability
Source: Morris, R.G.M. et al., Place navigation impaired in rats with hippocampal lesions. Nature, 1982, 182(297), 681–683. Reprinted with permission from Nature. © 1982 Macmillan Magazines Limited.
Spatial navigation
Source: Maguire, E.A., Frackowiak, R.S.J. and Frith, C.D., Recalling routes around London: Activation of the right hippocampus in taxi drivers. Journal of Neuroscience, 1997, 17, 7103. © Society for Neuroscience.
Chapter 6:How Does Memory Function?
The Memory Process
Encode information into memory traces (stored bits of memory)
Process information and put into memory storage
Use retrieval to recall and output information when needed
Are Human Brains Like Computers?
• Information-processing approach: mind functions like a sophisticated computer
• Unlike computers, human minds have the capacity for consciousness ▪ Awareness of one’s own thoughts and
the external world▪ Focusing attention brings stimulus into
consciousness
Explicit and Implicit Memory
Explicit memory Conscious use of memory Searching memory for stored
information Implicit memory
Access and retrieve memories without conscious effort
The Traditional Three Stages Model of Memory
Sensory memory Information comes into sensory organs,
stored briefly in sensory form Short-term memory
Temporary holding tank for limited amounts of information
Long-term memory Permanent storage of memories
Sensory Memory: Iconic and Echoic Memory
Information received from sense organs lasts for short period of time
Acquire information primarily from sight (iconic memory) and hearing (echoic memory), but also through other senses (haptic memory)
Transfer occurs when we pay attention to sensory input to move it from iconic memory to short-term memory
Short-Term Memory: Where Memories Are Made (and Lost)
Temporary holding tank Utilizes dual-coding system
Memories stored visually or acoustically Limited capacity and duration
The Capacity of Short-term Memory: Seven (Plus or Minus Two)
George Miller Average person holds about 7 + 2 items in
STM Phone numbers, social security numbers,
etc. Chunking can help increase capacity
Grouping information into meaningful units
Number of chunks that can be held decreases as chunks get larger
The Duration of Short-term Memory: It’s Yours for 30 Seconds
Once passed into STM, information can only be kept for 30 seconds without some type of processing
Maintenance rehearsal Repetition of material in short-term
memory
How We Transfer Information from Short-Term to Long-Term Memory
Maintenance rehearsal produces a weak transfer into LTM
Elaborative rehearsal Forming associations, or mental
connections, between information in STM to information already stored in LTM
Levels of Processing Model
Fergus Craik and Robert Lockhart The more thoroughly or deeply you
process information, the stronger the transfer to LTM
Both maintenance and elaborative rehearsal allow for transfer to LTM, but elaborative rehearsal involves a deep level of processing Difference between simply repeating
material and thinking about material Pays off in terms of storage and retrieval
of information
The Capacity of Long-term Memory
LTM is where information is stored for long periods of time
Limitless capacity Capacity problems are likely related to
lack of focus or lack of space in STM or working memory
Major Functions of Memory
Encoding—how we break down the information coming into our senses
Storage—keeping memories in our long term memory
Retrieval—process in which information in your memory can be recalled
Encoding in Long-term Memory
Encoding occurs in several forms Acoustic (sound), visual, semantic
Semantic encoding is most common Stores general meaning, rather than all
sensory details Encode and connect new information
with already stored information in LTM
Organization in Long-term Memory
Schemata – generalized knowledge structures Filing systems for knowledge about
particular concepts Default values for missing information
Various types of schemata Object, abstract concept, person Stereotypes Scripts
Types of Long-Term Memory
Declarative memory – explicit memory for knowledge easily verbalized (e.g. names, dates)
Two parts of declarative memory Semantic memory – concepts Episodic memory – memory for events
▪ Also called autobiographical memory▪ Memories have personal awareness
Gender and Autobiographical Memory
Females betters able to recall emotional childhood memories
Females tend to organize autobiographical memories in more diverse categories (i.e. more elaborative processing)
Procedural Memory
Memory that is not readily put into words - procedures for skills such as riding a bike, tying shoe, etc.
Often is implicit memory (unconscious) Tends to last longer than declarative
memory Studies from people with amnesia suggest
that procedural memory is a separate memory system
Retrieval, Recognition, and Recall
Retrieval – act of moving information from LTM back to working memory or consciousness Probe or cue sent in search of stored
memory traces Recall task – probe relatively weak and
does not contain much cue information (e.g. essay question)
Recognition task – probe stronger, contains more cue information (e.g. multiple choice question)
Memory must be available and accessible
Tips for Improving Memory
Pay attention, minimizing distractions Do not cram for exams
Distributed is better than massed practice
Use elaborative rehearsal Use overlearning Use mnemonic devices
Acronyms (APA), acrostics(rhyme or saying)▪ Remember the major functions of memory:
Ellen stopped remembering (encoding, storage, retrieval)
Is Memory Accurate?
Flashbulb memories – detailed memories of emotionally charged events These memories are not always accurate Store gist of information in LTM, not
exact details Examples of flashbulb memories:
▪ Attacks on 9/11▪ Assassination of JFK ▪ Birth of child▪ Wedding
Eyewitness Memory
Elizabeth Loftus Eyewitness memory can be manipulated
by expectations Memories can be permanently altered by
things that happen after we encode memories (false memories) False memories become part of memory
of original event
Myers’ PSYCHOLOGY
(7th Ed)
Chapter 9Memory
James A. McCubbin, PhDClemson University
Worth Publishers
Memory
Memory persistence of learning over
time via the storage and retrieval of information
Flashbulb Memory a clear memory of an
emotionally significant moment or event
Memory
Memory as Information Processing similar to a computer
write to file save to disk read from disk
Encoding the processing of information into the
memory system i.e., extracting meaning
Memory
Storage the retention of encoded
information over time Retrieval
process of getting information out of memory
Memory
Sensory Memory the immediate, initial recording
of sensory information in the memory system
Working Memory focuses more on the processing
of briefly stored information
Memory
Short-Term Memory activated memory that holds a few
items briefly look up a phone number, then
quickly dial before the information is forgotten
Long-Term Memory the relatively permanent and
limitless storehouse of the memory system
A Simplified Memory Model
Externalevents
Sensorymemory
Short-termmemory
Long-termmemory
Sensory inputAttention to importantor novel information
Encoding
Encoding
Retrieving
Encoding: Getting Information In
Encoding
Effortful Automatic
Encoding
Automatic Processing unconscious encoding of incidental
information space time frequency
well-learned information word meanings
we can learn automatic processing reading backwards
Encoding
Effortful Processing requires attention and conscious
effort Rehearsal
conscious repetition of information to maintain it in consciousness to encode it for storage
Encoding
Ebbinghaus used nonsense syllables TUV ZOF GEK WAV the more times practiced on Day 1,
the fewer repetitions to relearn on Day 2
Spacing Effect distributed practice yields better
long- term retention than massed practice
Encoding
20
15
10
5
08 16 24 32 42 53 64
Time in minutestaken to relearnlist on day 2
Number of repetitions of list on day 1
Encoding: Serial Position Effect
12
Percentage of words
recalled
0
90
80
70
60
50
40
30
20
10
Position of word in list
1 2 3 4 5 6 7 8 9 10 11
Serial Position Effect--tendency to recall best the last items in a list
What Do We Encode?
Semantic Encoding encoding of meaning including meaning of words
Acoustic Encoding encoding of sound especially sound of words
Visual Encoding encoding of picture images
Encoding
Encoding
Imagery mental pictures a powerful aid to effortful processing,
especially when combined with semantic encoding
Mnemonics memory aids especially those techniques that use
vivid imagery and organizational devices
Encoding
Chunking organizing items into familiar,
manageable units like horizontal organization--
1776149218121941 often occurs automatically use of acronyms
HOMES--Huron, Ontario, Michigan, Erie, Superior
ARITHMETIC--A Rat In Tom’s House Might Eat Tom’s Ice Cream
Encoding: Chunking
Organized information is more easily recalled
Encoding Hierarchies
complex information broken down into broad concepts and further subdivided into categories and subcategories Encoding
(automatic or effortful)
Imagery(visualEncoding)
Meaning(semanticEncoding)
Organization
Chunks Hierarchies
Storage:Retaining Information
Iconic Memory a momentary sensory memory of
visual stimuli a photographic or picture image
memory lasting no more that a few tenths of a second
Echoic Memory momentary sensory memory of
auditory stimuli
Storage:Short-Term Memory
Short-Term Memory limited in
duration and capacity
“magical” number 7+/-2
0102030405060708090
3 6 9 12 15 18
Time in seconds between presentationof contestants and recall request
(no rehearsal allowed)
Percentagewho recalledconsonants
Storage:Long-Term Memory
How does storage work? Karl Lashley (1950)
rats learn maze lesion cortex test memory
Synaptic changes Long-term Potentiation
increase in synapse’s firing potential after brief, rapid stimulation
Strong emotions make for stronger memories some stress hormones boost learning and
retention
Storage:Long-Term Memory
Amnesia--the loss of memory Explicit Memory
memory of facts and experiences that one can consciously know and declare
also called declarative memory hippocampus--neural center in limbic system
that helps process explicit memories for storage
Implicit Memory retention independent of conscious
recollection also called procedural memory
Storage: Long-Term Memory Subsystems
Types oflong-termmemories
Explicit(declarative)
With consciousrecall
Implicit(nondeclarative)
Without conscious recall
Facts-generalknowledge(“semanticmemory”)
Personally experienced
events(“episodic memory”)
Skills-motorand cognitive
Dispositions-classical and
operant conditioning
effects
Storage:Long-Term Memory
MRI scan of hippocampus (in red)
Hippocampus
Retrieval: Getting Information Out
Recall measure of memory in which the
person must retrieve information learned earlier
as on a fill-in-the blank test Recognition
Measure of memory in which the person has only to identify items previously learned
as on a multiple-choice test
Retrieval
Relearning memory measure that
assesses the amount of time saved when learning material a second time
Priming activation, often
unconsciously, of particular associations in memory
Retrieval Cues
0
10
20
30
40
Water/land
Land/water
Water/water
Different contexts for hearing and recall
Same contexts for hearing and recall
Land/land
Percentage ofwords recalled
Retrieval Cues
Deja Vu (French)--already seen cues from the current situation may subconsciously
trigger retrieval of an earlier similar experience "I've experienced this before."
Mood-congruent Memory tendency to recall experiences that are consistent
with one’s current mood memory, emotions, or moods serve as retrieval
cues State-dependent Memory
what is learned in one state (while one is high, drunk, or depressed) can more easily be remembered when in same state
Retrieval Cues
After learning to move a mobile by kicking, infants had their learning reactivated most strongly when retested in the same rather than a different context (Butler & Rovee-Collier, 1989).
Forgetting
Forgetting as encoding failure Information never enters the long-
term memory
Externalevents
Sensorymemory
Short-term
memory
Long-term
memory
Attention
Encoding
Encoding
Encodingfailure leadsto forgetting
Forgetting
Forgetting as encoding failure
Which penny is the real thing?
Forgetting
Ebbinghaus forgetting curve over 30 days-- initially rapid, then levels off with time12345 10 15 20 25 30
10
20
30
40
50
60
0
Time in days since learning list
Percentage oflist retainedwhen relearning
Forgetting
The forgetting curve for Spanish learned in school
Retentiondrops,
then levels off
1 3 5 9½ 14½ 25 35½ 49½Time in years after completion of Spanish course
100%
90
80
70
60
50
40
30
20
10
0
Percentage oforiginal
vocabularyretained
Retrieval
Forgetting can result from failure to retrieve information from long-term memory
Externalevents
Attention
Encoding
Encoding
Retrieval failureleads to forgetting
Retrieval
Sensorymemory
Short-termmemory
Long-termmemory
Forgetting as Interference
Learning some items may disrupt retrieval of other information Proactive (forward acting)
Interference disruptive effect of prior learning on
recall of new information Retroactive (backwards acting)
Interference disruptive effect of new learning on
recall of old information
Forgetting as Interference
Forgetting
Retroactive Interference
Without interferingevents, recall isbetter
After sleep
After remaining awake
1 2 3 4 5 6 7 8Hours elapsed after learning syllables
90%
80
70
60
50
40
30
20
10
0
Percentageof syllables
recalled
Forgetting
Forgetting can occur at any memory stage
As we process information, we filter, alter, or lose much of it
Forgetting- Interference
Motivated Forgetting people unknowingly revise
memories Repression
defense mechanism that banishes from consciousness anxiety-arousing thoughts, feelings, and memories
Memory Construction
We filter information and fill in missing pieces
Misinformation Effect incorporating misleading
information into one's memory of an event
Source Amnesia attributing to the wrong source an
event that we experienced, heard about, read about, or imagined (misattribution)
Memory Construction
Eyewitnesses reconstruct memories when questioned
Depiction of actual accident
Leading question:“About how fast were the carsgoing when they smashed intoeach other?”
Memoryconstruction
Memory Construction
Memories of Abuse Repressed or Constructed?
Child sexual abuse does occur Some adults do actually forget such episodes
False Memory Syndrome condition in which a person’s identity and
relationships center around a false but strongly believed memory of traumatic experience
sometimes induced by well-meaning therapists
Memory Construction
Most people can agree on the following: Injustice happens Incest happens Forgetting happens Recovered memories are commonplace Memories recovered under hypnosis or
drugs are especially unreliable Memories of things happening before
age 3 are unreliable Memories, whether false or real, are
upsetting
Improve Your Memory
Study repeatedly to boost recall Spend more time rehearsing or
actively thinking about the material
Make material personally meaningful
Use mnemonic devices associate with peg words--something
already stored make up story chunk--acronyms
Improve Your Memory
Activate retrieval cues--mentally recreate situation and mood
Recall events while they are fresh-- before you encounter misinformation
Minimize interference Test your own knowledge
rehearse determine what you do not yet
know
3-1: Structure of the Human Brain (Figure 3-6)
Teresa M. McDevitt, Jeanne Ellis OrmrodChild Development and Education
Copyright ©2002 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
3-2: Neurons in the Brain (Figure 3-5)
Teresa M. McDevitt, Jeanne Ellis OrmrodChild Development and Education
Copyright ©2002 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
3-3: Examples of Risk Factors for Healthy Neurological Development (Table 3-1)
Teresa M. McDevitt, Jeanne Ellis OrmrodChild Development and Education
Copyright ©2002 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
5 BASIC PRINCIPLES OF DARWINIAN EVOLUTION THEORY[FROM: MICHAEL SHERMER’S (2002) In Darwin’s Shadow: The life and Science of Alfred Russel Wallace. New York, NY: Oxford University Press, p. 207.]
EVOLUTION: CHANGE (in behavior)THROUGH TIME. DESCENT WITH MODIFICATION: THE MODE OF EVOLUTION BY
BRANCHING COMMON DESCENT. GRADUALISM: CHANGE (in behavior) IS SLOW, STEADY, STATELY.
NATURA NON FACIT SALTUS. GIVEN ENOUGH TIME EVOLUTION CAN ACCOUNT FOR THE ORIGIN OF NEW SPECIES.
MULTIPLICATION OF SPECIATION: EVOLUTION PRODUCES NOT JUST NEW SPECIES (behavior), BUT AN INCREASING NUMBER OF NEW SPECIES (behaviors).
NATURAL SELECTION: THE MECHANISM OF EVOLUTIONARY CHANGE CAN BE SUBDIVIDED INTO FIVE STEPS: (SEE NEXT SLIDE).
FIVE STEPS OF NATURAL SELECTION
1. POPULATIONS [behaviors] TEND TO INCREASE INDEFINITELY IN A GEOMETRIC RATIO. [FROM OBSERVATION]
2. IN A NATURAL ENVIRONMENT, HOWEVER, POPULATION [behavior] NUMBERS STABILIZE AT A CERTAIN LEVEL. [FROM OBSERVATION]
THERE MUST BE A “STRUGGLE FOR EXISTENCE” SINCE NOT ALL ORGANISMS [behaviors] PRODUCED CAN SURVIVE. [FROM INFERENCE]
THERE IS VARIATION IN EVERY SPECIES [behaviors]. [FROM OBSERVATION]
IN THE STRUGGLE FOR EXISTENCE, THOSE VARIATIONS THAT ARE BETTER ADAPTED TO THE ENVIRONMENT LEAVE BEHIND MORE OFFSPRING THAN THE LESS WELL ADAPTED INDIVIDUALS, ALSO KNOWN AS DIFFERENTIAL REPRODUCTIVE SUCCESS. [FROM INFERENCE]
BEHAVIORISTS’:BASIC ASSUMPTIONS OF BEHAVIORISM
PRINCIPLES OF LEARNING SHOULD APPLY EQUALLY TO DIFFERENT BEHAVIORS AND TO DIFFERENT SPECIES OF ANIMALS
LEARNING PROCESSES CAN BE STUDIED MOST OBJECTIVELY WHEN THE FOCUS OF STUDY IS ON STIMULI AND RESPONSES.
INTERNAL PROCESSES ARE LARGELY EXCLUDED FROM SCIENTIFIC STUDY
LEARNING INVOLVES A BEHAVIOR CHANGE ORGANISMS ARE BORN AS BLANK SLATES (tabula rasa). LEARNING IS LARGELY THE RESULT OF ENVIRONMENTAL
EVENTS. THE MOST USEFUL THEORIES TEND TO BE PARSIMONIOUS
ONES.
Concept Map:Behavioral Approaches
Approaches to Learning
Social Cognitive Approachesto Learning
SOCIAL COGNITIVEAPPROACHES TO
LEARNING
Bandura’s SocialCognitive TheoryBandura’s SocialCognitive Theory
Evaluating theSocial Cognitive
Approaches
Evaluating theSocial Cognitive
Approaches
Cognitive Behavior
Approaches
ObservationalLearning
Social Cognitive Approachesto Learning
Bandura’s social cognitive theory Social cognitive theory Reciprocal determinism model Self-efficacy
Bandura’s Reciprocal Determinism Model of Learning
BBehavior
P/CPerson and
cognitive factors
EEnvironment
Social Cognitive Approachesto Learning
Observational learning What is observational learning? The classic Bobo doll study Bandura’s contemporary model of
observational learning▪ Attention▪ Retention▪ Motor reproduction▪ Reinforcement of incentive conditions
Social Cognitive Approachesto Learning
Cognitive behavior approaches and self-regulation Cognitive behavior approaches
▪ Self-instructional methods
Social Cognitive Approachesto Learning
Self-regulatory learning▪ A model of self-regulatory learning
Self-Evaluationand Monitoring
Putting a Plan intoAction and Monitoring It
Goal Setting andStrategic Planning
Monitoring Outcomesand Refining Strategies
Self Regulated Learning:From Social/Cognitive Theory.
Key people:Bandura; Schunk; Zimmerman.
Key elements:
Goal Setting Planning Self-motivation (intrinsic motivation) Attention control Application of learning strategies Self-monitoring Self-evaluation Self-reflection
General Assumptions of Cognitive Theories
Some Learning Processes may be unique to human beings.
Cognitive processes are the focus of study. Objective, systematic observations of people’s
behavior should be the focus of scientific inquiry; however, inferences about unobservable mental processes can often be drawn from behavior.
· Individuals are actively involved in the learning process.
· Learning involves the formation of mental representations or associations that are not necessarily reflected in overt behavior changes.
Implications of Cognitive Theories
Cognitive processes influence learning. As children grow, they become capable of
increasingly more sophisticated thought. People organize the things they learn.· New information is most easily acquired when
people can associate it with things they have already learned.
· People control their own learning.
Some key Cognitive theorists
Jean Piaget (French) Lev Vygotsky (RUSSIAN) Edward Tolman (American) Jerome Bruner (American) Kurt Lewin (German)
Kurt Lewin (From Alfred Marrow’s book)
BH = f (P+E)
BARRIER
GOAL
REGION
PSYCHOLOGICAL LIFE SPACE
PERSON
NEEDS
ABILITIES
-
+
FOREIGN HULL VECTORS
VALENCES
Concept Map: Chapter Eight Overview
The Cognitive Information-Processing Approach
Characteristics of theInformation-Processing
Approach
Characteristics of theInformation-Processing
Approach
THE COGNITIVE INFORMATION-
PROCESSING APPROACH
Exploring theInformation-Processing
Approach
The Cognitive Information-Processing Approach
Exploring the information-processing approach Cognitive psychology
The Cognitive Information-Processing Approach
Characteristics of the information-processing approach Thinking Change mechanisms
▪ Encoding▪ Automaticity▪ Strategy construction▪ Transfer
Self-modification▪ Metacognition
Memory
MEMORY
What isMemory?What is
Memory?Retrieval and
ForgettingRetrieval and
Forgetting
StorageEncoding
Memory
What is memory?
ENCODING
Gettinginformationinto memory
STORAGE
Retaininginformationover time
RETRIEVAL
Takinginformationout of storage
Memory
Encoding Rehearsal Deep processing
▪ Levels of processing theory Elaboration Constructing images Organization
▪ Chunking
Memory
Storage Memory’s time frames
▪ Sensory memory▪ Short-term (working) memory
▪ Memory span
▪ Long-term memory
Key Ideas in Information Processing Theory
Teresa M. McDevitt, Jeanne Ellis OrmrodChild Development and Education
Copyright ©2002 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
I Sensation and Perception
II AttentionA. Distractibility decreases; sustained attention increases
B. Attention becomes increasingly purposeful
III Working Memory A. Processing speed increases
B. Children acquire more effective cognitive processes
C. The physical capacity of working memory may increase somewhat
IV Long-Term MemoryA. The amount of knowledge stored in long-term
memory increases
B. Knowledge becomes increasingly symbolic in nature
C. Children’s knowledge about the world becomes increasingly integrated
D. Children’s growing knowledge base facilitates more effective learning
5-1: A model of the human information processing system (Figure 5-1)
Teresa M. McDevitt, Jeanne Ellis OrmrodChild Development and Education
Copyright ©2002 by Pearson Education, Inc.Upper Saddle River, New Jersey 07458
All rights reserved.
Atkinson and Shiffrin’s Theory of Memory
Baddeley’s Model of Memory
Visuospatialscratchpad
Centralexecutive
Articulatoryloop
Storage: Long-Term Memory’s Contents
Long-term memoryLong-term memory
Nondeclarative(implicit)
Nondeclarative(implicit)Declarative
(explicit)Declarative
(explicit)
Episodic memoryEpisodic memory Semantic memorySemantic memory
Memory
Storage Content knowledge and how it is
represented in long-term memory▪ Content knowledge▪ Network theories▪ Schema theories
▪ Schema▪ Script
Memory
Retrieval and forgetting Retrieval
▪ Serial position effect▪ Primacy effect▪ Recency effect▪ Encoding specificity principle▪ Recall▪ Recognition
Memory
Retrieval and forgetting Forgetting
▪ Cue-dependent forgetting▪ Interference theory▪ Decay theory
Abraham Maslow’s
Perspectives on motivation The humanist perspective
▪ Maslow’s hierarchy of needs▪ Physiological▪ Safety▪ Love and belongingness▪ Esteem▪ Self-actualization