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Chapter 12
Learning and Memory:
Basic Mechanisms
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•
Chapter 12 Outline
• The Nature of Learning
• Synaptic Plasticity: Long-term potentiation and Longterm Depression
• Perceptual Learning
• Classical Conditioning
• Instrumental Conditioning
• Relational Learning
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• Studies of the biology of learning has produced
learning categories that differ somewhat from
those used in most General Psychology courses.
• Learning:
the process by which experience changes
the nervous system, and hence changes behavior.
• 1.
_____________________: the ability to recognize
familiar stimuli.
• Facial recognition & the ability to identify “strangers”
• Accomplished by changes in the association cortex.
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• Learning
•
2. Stimulus-response learning: establishing connections
involved in perception and those involved in movement.
Learning to automatically
__________________________________________________
__________________________________________________.
• Classical conditioning
• Operant conditioning
• (3?) Motor learning: most skilled movements involve
practice designed to “improve” the relationship between
_________________, batting practice, learning to drive a
car or ride a bicycle.
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• Learning
• (4 or 3?).
_____________________: learning the
relationships between individual stimuli.
• Learning the locations of objects in a room
• Learning the locations and relationships of the structures
that compose the limbic system.
• Episodic learning: sequences of events
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• The Nature of Learning
• Classical conditioning
• A learning procedure; when a stimulus that initially
produces no particular response is followed several
times by an unconditioned stimulus that produces a
defensive or appetitive response. This type of learning
involves:
•
•
•
•
Unconditioned stimulus (US)
Unconditioned response (UR)
Conditioned stimulus
(CS)
Conditioned response
(CR)
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Classical Conditioning
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• The Nature of Learning
• ______________
• The hypothesis proposed by Donald Hebb that the
cellular basis of learning involves strengthening of
a synapse that is repeatedly active when the
___________________________.
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• The Nature of Learning
• Instrumental conditioning (Operant Conditioning)
• A learning procedure whereby the effects of a
particular behavior in a particular situation increase
(reinforce) or decrease (punish) the probability of the
behavior; also called operant conditioning.
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Operant Conditioning
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• The Nature of Learning
• Reinforcing stimulus
• An ______________stimulus that follows a particular
behavior and thus makes the behavior become more
frequent.
• Punishing stimulus
• An ______________stimulus that follows a particular
behavior and thus makes the behavior become less
frequent.
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Overview of Learning Systems
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• Memory Formation
• Neural circuits that contain memories are probably
established by strengthening some synapses, and
weakening others.
• At a behavioral level:
• ______________may be produced by weakening
synapses (or strengthening inhibitory inputs).
• ________________may be produced by strengthening
synapses (or weakening inhibitory inputs).
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• Learning and Synaptic Plasticity
• Induction of long-term potentiation
• Long-term potentiation
• A long-term increase in the excitability of a neuron
to a particular synaptic input caused by repeated highfrequency activity of that input.
• Hippocampal formation
• A forebrain structure of the temporal lobe, constituting
an important part of the limbic system; includes the
___________________________________________
__________________________________________.
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• Learning and Synaptic Plasticity
• Induction of long-term potentiation
• Population EPSP
• An evoked potential that represents the EPSPs of a
________________.
• Multi-unit recording.
• Long-term potentiation can follow the Hebb rule.
• It can last for several months.
• A. Stimulate preforant path (entorhinal cortex), a burst of
several seconds of stimulation.
• B. Potentiation observed by a larger population of EPSP
responses in dentate gyrus (lasts for months).
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Hippocampal formation & long-term potentiation
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• Learning and Synaptic Plasticity
• Induction of long-term potentiation
• Associative long-term potentiation
• A long-term potentiation in which concurrent
stimulation of weak and strong synapses to a
given neuron generates
______________________________________________
_______________________________________.
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Associative
long-term
potentiation.
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• Learning and Synaptic Plasticity
• Role of NMDA receptors
• NMDA receptor
• A specialized ionotropic glutamate receptor that
controls a calcium channel that is normally blocked
by Mg2+ ions; involved in long-term potentiation.
• Dendritic spike
• Normally only axons can produce action potentials.
However,
______________________________________________
_____________________________________________.
• An action potential that occurs on the ___________ of
some types of pyramidal cells.
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Synaptic
strengthening only
occurs if
_________________
_________________
_________________
________________.
Molecules of the
neurotransmitter must
bind with receptors in
a depolarized
dendritic spine.
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Depolarization evicts the Mg2+ ion and unblocks the
calcium channel. The NMDA receptor requires both
the
___________________________________________
__________________________________________.
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Associative long-term potentiation: weak synapses
activated when a strong synapse is activated
become _________________
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• Learning and Synaptic Plasticity
• Role of NMDA receptors
• The special properties of NMDA receptors account for
long-term potentiation and its associative nature.
• Q: How does the postsynaptic membrane change as a
result of long-term potentiation?
• A:
_____________________________________________
____________________________________________.
• AMPA receptor
• An ionotropic glutamate receptor that controls a
sodium channel; when its open, it produces EPSPs.
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Growth of AMPA receptors after LTP.
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• Learning and Synaptic Plasticity
• Mechanisms of synaptic plasticity
• How does the influx of calcium ions into the dendritic
spine result in the insertion of additional AMPA
receptors?
• CaM-KII
• Type II calcium-calmodulin kinase, an enzyme that
must be activated by calcium; may play a role in the
establishment of long-term potentiation.
• Nitric oxide synthase
• An enzyme responsible for the production of nitric
oxide.
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Entry of Ca2+ into the
spine causes the synthesis
and release of NO which
serves as a second
messenger to increase
glutamate release.
LTP requires protein
synthesis,
______________________
______________________
______________________
This results in larger
excitatory postsynaptic
potentials.
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• Learning and Synaptic Plasticity
• Long-term depression
• Long-term depression (LTD)
• A long-term decrease in the excitability of a neuron to
a particular synaptic input caused by stimulation of
the terminal button while the postsynaptic membrane
is hyperpolarized.
• The combined effect of LTP and LTD (in
associated circuits) are believed to be necessary
for ________________________.
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• Perceptual Learning
• Perceptual learning
• A type of learning that involves _____________
• It provides subjects with the ability to perform an
appropriate behavior in an appropriate situation.
• Perceptual learning can involve learning to recognize
entirely new stimuli, or it can involve learning to
recognize changes or variations in familiar stimuli.
“I like your new hair style”.
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Perceptual
learning
involves
changes in
synapses in
the inferior
temporal
cortex.
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If an
association is
formed
between
pictures and
sounds (a
barking dog
& a photo of
a dog),
the picture
will activate
the “memory”
for the sound.
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Photos of implied
motion activate the
MT/MST region of
the visual
association cortex in
fMRI studies.
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• Classical Conditioning
• Follows the model for long-term potentiation and
perceptual learning paradigm.
• In the formation of conditional emotional responses
(foot-shock & tone) the amygdala receives inputs from
the auditory and somatosensory systems. Weak
synapses (auditory) input are strengthened via
association with strong synapses (painful stimulus) via
the Hebb rule. _______________ move into the
dendritic spine.
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• Instrumental Conditioning
• Operant conditioning must begin in the sensory
association cortex where perception takes place
and end in the motor association cortex where
movement is controlled.
• Reinforcement: Neural circuits involved in reinforcement
• Medial forebrain bundle (MFB)
• A fiber bundle that runs in a rostral-caudal direction
through the basal forebrain and lateral hypothalamus;
electrical stimulation of these axons is reinforcing. This is
not the only ___________ area in the brain,
_____________________________________________.
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• Instrumental Conditioning and Motor Learning
• Reinforcement: Neural circuits involved in reinforcement
• Ventral tegmental area (VTA)
• A group of _______________neurons in the ventral
midbrain whose axons form the mesolimbic and
mesocortical system; plays a critical role in
reinforcement.
• There may be more than one reward system, but this is
an important system involved in reward.
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Basal ganglia
connections
involved in
controlling
automatic
complex motor
behaviors (e.g.
driving a
standard
transmission
automobile).
No longer have
to think about
it.
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• Instrumental Conditioning and Motor Learning
• Reinforcement: Neural circuits involved in reinforcement
• _______________________
• A nucleus of the basal forebrain near the septum;
receives dopamine-secreting terminal buttons from
neurons of the ventral tegmental area and is thought to
be involved in ___________________________.
• Electrical Stimulation of the VTA reward center or
administration of cocaine, food or sex causes release of
___________________________.
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Nucleus accumbens & Ventral Tegmental Area
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Dopamine levels
in N. accumbens
increase when a
rat presses a
lever that
delivers
electrical pulses
to the VTA
reward center.
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• Relational Learning
• Human anterograde amnesia
• _______________ amnesia
• Amnesia for events that occur _______ some
disturbance
to the brain, such as head injury or certain
degenerative brain diseases.
• A person with anterograde amnesia can remember
events in the past and those that occurred just prior to
the trauma; however, they cannot
__________________________________________
______________________________________.
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• Reinforcement Systems
• A. Must detect the presence of the reinforcing stimulus.
• B. Must strengthen the connections between the detection
of the S+ and the instrumental response.
• Reinforcement occurs when neural circuits detect a
reinforcing stimulus, and cause the activation of
_______________________________.
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• Reinforcement
•
•
Reinforcement is not automatic because it also depends on the
______ of the animal (food is a reward only if the subject is
hungry).
The prefrontal cortex appears to turn on the reinforcement
system when it determines that the ongoing behavior is likely to
bring the subject ___________________. Prefrontal cortex
projections to VTA secrete glutamate which causes VTA to
greatly increase dopamine secretion in N. accumbens.
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• Relational Learning
• Human anterograde amnesia
• Unable to learn new information.
• ___________amnesia
• Amnesia for events that ___________ some
disturbance
to the brain, such as a head injury or
electroconvulsive shock.
• People with retrograde amnesia may not be able to
recall events in the past or events that occurred just
_______________________.
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Amnesia
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• Relational Learning
• Human anterograde amnesia
• ________________ syndrome
• Permanent anterograde amnesia caused by brain
damage resulting from chronic alcoholism or
malnutrition. Unable to form _____________.
• ______________
• The reporting of memories of events that did not take
place without the intention to deceive, seen in people
with Korsakoff’s syndrome. When asked about
recent events subjects fabricate a possible truth,
rather than say I don’t know. They appear to believe
in what they are saying. Temporal lobe damage may
produce the same effect (H.M.)
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• Relational Learning
• Human anterograde amnesia
• Short-term memory
• Immediate memory for events, which may or may not
be consolidated into long-term memory.
• Long-term memory
• Relatively stable memory of events that occurred in
the more distant past.
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• Relational Learning
• Human anterograde amnesia
• ___________________
• The process by which short-term memories are
converted into long-term memories.
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Broken drawings, patients with
anterograde amnesia are capable
of learning that set I stilumli
correspond to set V stimuli, and
other kinds of perceptual and
motor learning tasks. They
cannot talk about their
experiences. The consolidation
process does not work for
_________________________.
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• Relational Learning
• Human anterograde amnesia
• Declarative memory
• Memory that can be ________________, such as
memory for events in a person’s past.
• Nondeclarative memory
• Memory whose formation does not depend on the
_______________________; a collective term for
perceptual, stimulus-response, and motor memory.
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• Relational Learning
• Anatomy of anterograde amnesia
• Damage to the hippocampus & associated regions
cause anterograde amnesia.
• A. Perirhinal cortex (__________________________)
• A region of limbic cortex adjacent to the hippocampal
formation that, along with the parahippocampal
cortex, relays information between the entorhinal
cortex and other regions of the brain.
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• Relational Learning
• Anatomy of anterograde amnesia
• B. Parahippocampal cortex (_____________________)
• A region of limbic cortex adjacent to the hippocampal
formation that, along with the perirhinal cortex, relays
information between the entorhinal cortex and other
regions of the brain.
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• NMDA Receptors in the _______________
• Enhance the ability of subjects to learn quickly via longterm potentiation.
• However, these receptors and associated neurons are
sensitive to metabolic disorders.
• Disturbances that result in high release of glutamate
allow high levels of calcium to enter the cell, and the
high levels of calcium are toxic to the neuron.
• Hippocampus is important for the consolidation of
declarative memories including the “order” in which
events occurred, and the “contex” of their occurance.
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Hippocampal Formation
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Greater hippocampal activation results in better
free recall
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• Relational Learning
• Declarative memory has two components.
• A. _____________________
• Memory of a collection of perceptions of events
organized in
__________________________________________
_____________________________________.
• B _________________ memories
• A memory of facts and general information.
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• Relational Learning
• Spatial memories
• Bilateral medial temporal lesions produce the most
profound impairment in spatial memory, but significant
deficits can be produced by damage that is limited to the
right hemisphere.
• Functional imaging studies have shown that the right
hippocampal formation becomes active when a person
is remembering or performing a __________________.
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Virtual reality navigation and activation of the
right hippocampus.
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• Relational Learning in Laboratory Animals
• Place cells in the hippocampal formation
• _______________
• A neuron that becomes active when the animal is in
a particular location in the environment; most
typically found in the hippocampal formation.
• Firing rates of place cells appear to reflect where the
subject _________________.
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Hippocampal lesions disrupt relational learning
Morris water maze
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Place cells fire
in accordance
to where a
subject expects
or believes that
it is located.
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Consolidation of relational memory may be disrupted
by Lidocaine injections right after learning occurred.
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• Relational Learning in Laboratory Animals
• Memories can be
_________________________________________
______________________________________.
• Reconsolidation
• A process of consolidation of a memory that occurs
subsequent to the original consolidation that can be
triggered by a reminder of the original stimulus; thought
to provide the means for modifying existing memories.
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• Targeted mutations can be produced that either
reduce NMDA receptor development in mice, or even
enhance it.
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Targeted knock-out mutations produce fewer
NMDA receptors, and impair relational learning
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• Targeted mutations can also produce genetically
“smart” mice that show an increase in the production
of NMDA receptors.
• Enhanced long-term potentiation is seen in these
•
•
modified mice.
They learn the Morris water maze faster than normal
mice.
But they may be more
___________________________________________
_________________________________________.
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• Neurogenesis in the hippocampus
• Stem cells in the subgranular zone of the adult hippocampus
divide and give rise to granule cells which migrate to the
dentate gyrus.
• Rats trained on the relational task in the Morris water maze
______________________________________ in the
dentate gyrus. These new neurons participate in learning.
Many new connection have to be established for this new
tissue to benefit the organism. Thus this process takes time.
• The volume of the posterior hippocampus is larger in London
taxi drivers than in control subjects (2 years of training to
receive a license).
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