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Chapter 12
Learning and Memory
© Cengage Learning 2016
© Cengage Learning 2016
Learning
• Three categories of learning
– Reflexes
– Fixed action patterns (instincts)
– Learning
• Types of learning
– Associative learning
• Classical and operant conditioning
– Nonassociative learning
• Habituation and sensitization
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Reflexes Provide Fast, Reliable Responses
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Contagious Yawning Might Be a Fixed
Action Pattern
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Habituation and Sensitization
• Habituation occurs when an organism
reduces its response to unchanging,
harmless stimuli
• Sensitization occurs when repeated
exposure to a strong stimulus increases
response to other environmental stimuli
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Classical Conditioning
• Organisms learn that stimuli act as signals
that predict the occurrence of other
important events
• First articulated by Pavlov in 1927
– Conditioned responses (CR) are those
behaviors that must be learned
– Unconditioned responses (UCR) appear
without prior experience to a stimulus
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The Process of Classical Conditioning
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Operant Conditioning
• Studied by B.F. Skinner
• Organisms form connections between a
behavior and its consequences that impact
the subsequent frequency of that behavior
• Reinforcing and punishing consequences
increase and decrease likelihood of
repeating the behavior
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Learning at the Synapse
• Studying invertebrates gives a rich
opportunity to understand changes taking
place at the level of the synapse
• Frequently studied organisms
– Fruit flies
– Sea slug (Aplysia californica)
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Aplysia californica
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The Neuroanatomy of Aplysia
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Short-Term Habituation at the Synapse
• Habituation in Aplysia
– Gill-withdrawal reflex
– Reduced activity at synapse between sensory
and motor neurons
– Direct result of decreased neurotransmitter
release
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Short-Term Sensitization at the Synapse
• Sensitization in Aplysia
– A stimulus gains the ability to influence more
than one neural pathway
– Increased neurotransmitter release by
sensory neuron
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Habituation and Sensitization in Aplysia
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Long-Term Habituation and Sensitization at
the Synapse
• Long-term habituation training decreases
the number of presynaptic terminals of
sensory neurons
• Long-term sensitization training increases
the number of presynaptic terminals of
sensory neurons
• Both are likely the result of gene
expression processes controlled by
transcription factors
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Structural Changes in Synapses Result
from Learning
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Biochemical Correlates of Sensitization in
Aplysia
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The cAMP-PKA-MAPK-CREB Pathway
Leads to Long-Term Changes in Behavior
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Classical Conditioning at the Synapse
• Classical conditioning in Aplysia
– Sequential activation of sensory neurons by
CS and UCS leads to greater
neurotransmitter release
– Classical conditioning in Lymnaea can occur
to both rewarding unconditioned stimuli (food)
and aversive conditioning stimuli (electric
shock)
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Classical Conditioning in Aplysia
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Operant Conditioning at the Synapse
• Results when an organism’s naturally
occurring behavior becomes more or less
frequent in response to its consequences
• “Fix” what had been a fairly random
pattern of behavior into a more reliable,
stereotyped pattern
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Operant Conditioning in Aplysia
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Brain Structures and Circuits Involved in
Learning
• Classical conditioning of threat
– “Fear” is a conscious feeling of being afraid
– “Threat” is the unconscious mobilization of
defensive behaviors
• Amygdala plays an important role in the
classical conditioning of emotional
responses
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The Amygdala Participates in Threat
Conditioning
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Classical Conditioning of the Eyeblink
• Rabbit studies
– Nictitating membrane
– Interpositus nucleus of the cerebellum is
necessary for learning to occur
• Human studies
– The cerebellum is involved in classical
conditioning
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The Role of Interpositus Nucleus in
Classical Conditioning
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Cerebellar Circuits and Classical
Conditioning
• The Purkinje cells are perfectly situated to
influence the output of the cerebellum
• Learning will occur if the climbing-fiber and
parallel-fiber synapsing onto a Purkinje
cell are activated at the same time
• Reduced activity in the Purkinje cells is
known as long-term depression
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Connections within the Cerebellum
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Trace Conditioning
• Delay conditioning
– The CS overlaps the UCS
– No stimulus-free interval
• Trace conditioning
– The CS and the UCS do not overlap
– A stimulus-free interval occurs
– Requires the participation of forebrain areas
– Requires conscious, declarative processes
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Delay Versus Trace Conditioning
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Extinction
• Pavlov described how conditioned
responding would gradually decrease, or
undergo extinction, when the conditioned
stimulus was presented repeatedly without
the unconditioned stimulus
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Types of Memory
• Steps in the memory pathway
– Encoding
– Consolidation
– Retrieval
– Reconsolidation
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Information Processing Model
• Information flows through a series of
stages on its way to permanent storage in
memory
– Sensory memory
– Short-term memory
– Long-term memory
• Declarative memories (semantic and episodic)
• Nondeclarative memories (procedural)
• Anterograde amnesia
• Engrams
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Atkinson-Shiffrin Model of Memory
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Types of Long-Term Memory
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Brain Structures and Circuits Involved in
Memory
• Early efforts to locate memory functions
– Lashley: engram
– Penfield: recordings during surgery for
epilepsy
• Temporal lobe and memory
– H.M.’s anterograde amnesia
– The delayed nonmatching to sample (DNMS)
test (monkeys)
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Karl Lashley Observed the Results of Brain
Lesions on Maze-Learning Performance
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The Temporal Lobe and Memory
• Evidence of the temporal lobe’s
involvement in memory
– Case studies of patients with anterograde
amnesia
• Amygdala appears to play a role in
processing emotional memories
• The hippocampus involved in the
formation of long-term memories
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Surgical Removal of Henry Molaison’s
Temporal Lobe Tissue
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The Mirror-Drawing Task
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The Delayed Nonmatching to Sample
(DNMS) Task
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Long-Term Potentiation (LTP)
• Provide a basis for learning and memory
– The application of a rapid series of electrical
shocks to input pathways increases the
postsynaptic potentials in their target neurons
• LTP as a memory mechanism
– Associativity, cooperativity, and synaptic tags
• LTP and behavioral memory
– Spatial memory; avoidance situations
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The Hippocampus and Its Associated
Structures
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Long-Term Potentiation (LTP)
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LTP and the NMDA Receptor
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The Morris Water Maze Requires Spatial
Memory
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The Diencephalon and Memory
• Disruption of the hippocampus and other
areas of the temporal lobe results in
amnesia
• Case studies of patients with diencephalic
lesions support the role of this area in
memory
• Alcoholics and amnestic confabulatory
(Korsakoff’s) neurocognitive disorder
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Damage to the Diencephalon in Patient
N.A.
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Semantic Memory and the Cerebral Cortex
• Semantic knowledge is widely distributed
in the cortex
• Retrieving these distributed memories
requires a coordinated effort and the use
of “convergence zones”
– Left lateral inferior frontal gyrus
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Semantic Memories Are Widely Distributed
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Episodic Memory and the Cerebral Cortex
• Concept of an independent episodic
memory store for our personal
experiences
• Patients with source amnesia can create
new semantic memories but forget how
the knowledge was gained originally
• Prefrontal areas are involved with longterm management of episodic memories
• Use episodic memories to distinguish
between fantasy and reality
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Short-Term Memory and the Brain
• Four components of working memory
– A central executive
– The phonological loop
– The visuo-spatial scratchpad
– An episodic buffer
• The dorsolateral prefrontal cortex (DLPFC)
and the anterior cingulate cortex (ACC)
play roles in attentional aspects of shortterm memory
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Object Permanence
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The Striatum and Procedural Memory
• The striatum
– Role in forming procedural memories
– Basal ganglia
• Memories of motor patterns
– Nucleus accumbens
• Emotional and rewarding correlates of a procedure
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The Radial Arm Maze
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The Biochemistry of Memory
• Acetylcholine (ACh) is essential to
memory functions
• Cholinergic activity has different effects in
different phases of memory
– Increases in the hippocampus are associated
with better encoding of new information but
consolidation and retrieval of memory appear
to be impaired by high cholinergic activity
• Glutamate is involved in encoding and
consolidation of memories
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The Effects of Stress and Healthy Aging
on Learning and Memory
• Stress and healthy aging produce
relatively mild but noticeable changes in
the way memories are processed
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Effects of Stress on Memory
• The critical variable determining the
effects of stress on memory appears to be
timing
– In the Atkinson-Shiffrin model, memories pass
through a series of stages during which they
are relatively fragile and open to modification
– At each stage, stress and biochemical
correlates can have unique effects on how
information is encoded, stored, and retrieved
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Flashbulb Memories Seem More Vivid and
Complete
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Stress Has Different Effects at Different
Times in the Memory Process
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Effects of Norepinephrine and
Glucocorticoids on Memory
• The lateral nucleus of the amygdala is the
target for both norepinephrine and
glucocorticoids released by the adrenal
glands as a result of stress
• The stress-induced actions of
norepinephrine and glucocorticoids in the
amygdala initiate a “memory formation”
state in the prefrontal cortex, the
hippocampus, and the caudate nucleus
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Effects of Glucocorticoids and
Norepinephrine on Memories for Stressors
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The Effects of Healthy Aging on Memory
• Cognitive ability of healthy older adults is
stable
– Comparison of young adults, healthy older
adults, those at high risk for Alzheimer’s, and
those with Alzheimer’s disease
– People compensate for age-related declines
in brain function
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Electronic Games and Healthy Aging
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