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Learning and Memory
The behavior of organisms can be separated into three major
categories:
 Reflexes
 Instincts
 Learned behaviors
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Reflexes - are involuntary responses to stimuli
- have the advantage of producing rapid, reliable
responses, but their inflexibility can be a
disadvantage when the environment changes.
Instincts - are automatic, but their resulting behaviors are
more complex.
- instinctive behaviors are consistent enough to be
referred to as fixed action patterns.
Learning - learning A relatively permanent change in behavior
or the capacity for changes in behavior due to
experience.
- provides organisms with the most flexible means
for responding to the environment.
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Types of Learning
Repeated touching can result to habituation due to the
reduced activity/excitatory potential at the synapse
between the sensory and motor neurons in habituation
was a direct result of the release of less neurotransmitter
Habituation can last up to 3 weeks
After Aplysia is sensitized by the administration of an
electric shock to the head or tail, touching the siphon
results in an enhanced gill-withdrawal response.
Longer action potentials leads to the stronger gillwithdrawal reflex that we observe in sensitization.
Aplysia Classical Conditioning-----ask
(a) Touching the siphon (CS−) is not paired with shock
and serves as a control.
(b) Touching the mantle (CS+) is always followed by
shock to the tail (UCS). (c) After several pairings of
touching the mantle (CS+) followed by shock (UCS),
touching the mantle alone now triggers gill withdrawal
(CR).
In the circled area in (b), the mantle shelf sensory
neurons are sequentially activated, first by touching the
mantle shelf and then by input from interneurons
serving the tail. This sequence produces increased
presynaptic facilitation, leading to the recording of
greater postsynaptic potentials in the motor neuron
than those recorded prior to training.
1. Associative Learning - occurs when an organism forms a
connection between two features of its environment.
example: Classical Conditioning
2. Nonassociative learning - A type of learning that involves a
change in the magnitude of responses to stimuli rather than
the formation of connections between elements or events.
example: 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.
example: following major disasters such as earthquakes,
people often experience exaggerated responses to movement,
light, and noise.
Classical Conditioning - A type of associative learning in
which a neutral stimulus acquires the ability to signal the
occurrence of a second, biologically significant event.
 Conditioned Stimulus (CS) refers to an environmental
event whose significance is learned, whereas an
(learning; bell sound)
 Unconditioned Stimulus (UCS) has innate meaning to
the organism. (unlearned; food)
 Conditioned responses (CR) are those behaviors that
must be learned (salivating to bell sound)
 Unconditioned Responses (UCR) appear without prior
experience with a stimulus. (salivating to food)
Using Invertebrates to Study Learning
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sea slug = Aplysia californica
Brains = Neural net
Touching the animal’s siphon reliably produces a
protective response known as the gill-withdrawal reflex,
in which the gill is retracted.
Classical Conditioning in Vertebrates
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fear responses in rats and eyeblink conditioning in
rabbits.
Classical Conditioning of Fear
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Amygdala plays a role in classical conditioning of
emotional response such as fear.
1. Rat hears a tone (CS)
2. Electric shock (UCS)
3. Stops eating and shows fear
4. Association is made between the tone and the
shock
5. When the rat hears the tone the amygdala
sends out a strong response for fear in the
absence of shock
Classical Conditioning of the Eyeblink
1. Rabbit hears a tone (CS)
2. Followed by a puff of air in the rabbit’s eye
(UCS) causing movement in the nictitating
membrane.
Nictitating Membrane - An additional, moveable inner eyelid
found in some birds, fish, and mammals but not in humans.
3. After several pairing of tone and puff the
rabbit blinks when they hear the tone even
without the puff of air.
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the importance of the interpositus nucleus in classical
conditioning shows how during learning there is an
increase in the structure’s response to tone/CS.
 Inactivation of this structure can inhibit classical
conditioning
Interpositus Nucleus - cerebellar nucleus thought to be
essential to classical conditioning in vertebrates.
 Lesions can change our behavior due to loss of that
structure and this change can be due to the lack of info
travelling via fibers affected by the lesion.
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Interpositus nucleus is primarily responsible for the
formation of the classically conditioned response of the
 nictitating membrane in rabbits; red nucleus only
suppresses but doesn’t prevent learning.
 Cerebellum damage and shrinkage is correlated with
speed of acquisition of CR
Cerebellar Circuits and Classical Conditioning
Purkinje cell - A cell in the cerebellum that influences
its activity by forming inhibitory synapses with the output
cells in the deep cerebellar nuclei.
- receives input from climbing and parallel fiber
Climbing Fiber - A fiber originating in the inferior olive of the
brainstem that forms synapses on the large Purkinje cells of
the cerebellar cortex.
Parallel Fiber - A fiber originating in the granule cells of the
cerebellum that synapses on the Purkinje cells.
- originate from granule cells
Granule Cell - A cell within the cerebellum that is the source
of parallel fibers.
- receive input from mossy fibers
Mossy Fibers - integrate info from parallel and climbing fiber.
- Originate from neurons in the pons.
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Purkinje cells form inhibitory synapses, located in the
deep cerebellar nuclei therefore influences the output
of the cerebellum
 learning will occur if the climbingfiber and parallel-fiber
synapses onto a Purkinje cell are activated at the same
time.
 Paired stimulation resulted in reduced activity in
Purkinje cell EPSPs. The reduced activity in the
 Purkinje cells is known as long-term depression, or LTD.
1. Three Events Occur: When the climbing and parallel
fibers are active, three things happen simultaneously in
the Purkinje cell: calcium (Ca2+) and sodium (Na+) ions
enter the cell, and a chemical known as protein kinase C
(PKC) is activated.
2. Fewer Glutamate Receptors: These events together
lead to a decrease in the number of glutamate receptors
in the Purkinje cell membrane. Since there are fewer
receptors to respond to glutamate, the result is a
reduction in EPSPs.
3. Connection to Learning: Even though a reduction in
activity might seem like it wouldn't help with learning,
this process of long-term depression (LTD) is actually
crucial for certain types of learning, like the eyeblink
conditioned response (CR), which involves the inferior
olive and climbing fibers. This reduction in EPSPs due to
fewer receptors is part of how this learning happens.
Trace Conditioning and Extinction
Delay Conditioning: The CS and UCS overlap; the CS is
continuous until the UCS is presented. This type of
conditioning is generally easier to learn because the stimuli
are presented closely together.
Example: The dogs learn to associate the tone with the food,
causing them to start salivating at the sound of the tone,
even before the food is presented.
Trace Conditioning: There is a gap between the end of the CS
and the beginning of the UCS. This requires the learner to
remember the CS during the gap, making it generally harder
to learn but offering insights into the learner's memory and
cognitive abilities.
Example: The dog will start salivating when they hear the bell,
even though it has stopped before the food arrives.
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Trace conditioning requires the forebrain structures to
hold the CS information during the stimulus-free
interval before transmission to cerebellum
NOTE: Classical conditioning in vertebrates involves the
amygdala (emotional learning) and the cerebellum (skeletal
reflexes).
- In addition to the cerebellum, trace conditioning requires
activity in the forebrain. Also require conscious, declarative
processes
Memory
Information Processing Models - theories of memory that
seek to explain the management of information by the brain,
from detection to storage to retrieval.
3 types of Long-Term Memory
1. Semantic memory - contains basic knowledge of facts and
language. Ex. “who is your mother?”
2. Episodic memory -relates to your own personal experience.
You use your episodic memory to remember the episodes of
your life. Ex. “where were u last Monday?”
3. Procedural memory - stores information about motor
skills
and procedures. Ex. riding a bicycle, using a software
program
 Semantic and episodic memory are both “Declarative
Memories” because they can easily be described with
words/declared.
 Procedural memories are difficult to verbalize but easy
to demonstrate or perform
 Declarative memories: conscious and explicit recall
involved
 Procedural Memories: unconscious and implicit recall
involved
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Classical conditioning, habituation, and sensitization are
also considered examples of nondeclarative processes.
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People with anterograde amnesia suffer from explicit
memory impairment but have an intact implicit memory
Engram - A physical memory trace in the brain.
Brain Mechanisms in Memory
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Lashley posed that no single area is more responsible
for learning and memory than any other.
Penfield’s study shows possible role for the temporal
lobe in the formation and retention of long-term
memories.
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conclude that hippocampal spatial maps are formed
within minutes of entering a new environment
In a study where they deleted he CA1 gene that has a
role in the NMDA receptors has a negative impact on
LTP
Disrupting “second messengers” transmission of signal
also negatively impacts LTP
When LTP is impaired and is in a same place, a new map
is formed instead of reactivation of old one
Spatial learning can also be impaired if a NMDA
antagonist is administered
The Diencephalon and Memory
 Composed of the thalamus and hypothalamus
 Patient N.A. suffered ffrom antero and retrograde
amnesia after being stabbed by a foil fencing sword in
the nose. Short term memory intact, long term impaired.
Korsakoff ’s syndrome - Anterograde amnesia resulting from
thiamine deficiency, typically found in chronic alcoholics.
Semantic Memory and the Cerebral Cortex
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“convergence zone,” or a particular location
responsible for assembling separate aspects of a
memory into a whole.
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convergence zone for semantic memories are areas
along the left lateral inferior frontal gyrus. Most active
when incorrect language/worl knowledge was used
The Temporal Lobe and Memory
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Patient H.M. proved that memories do not reside in the
medial temporal lobe itself necessarily essential for the
retrieval of stored memories.
Delayed Nonmatching To Sample (DNMS) Task
- A standard test of memory in which the subject must
identify the novel/new member of a stimulus pair following a
delay. (Monkey example)
 Study showed that lesions does not affect short term
memory but shows difficulty in forming long term
memories
Long-Term Potentiation (LTP)
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Long-Term Potentiation (LTP) is a process where
repeated stimulation strengthens the connections
between neurons, leading to more efficient signal
transmission. Example: Playing and practicing a new
note
 Ammon’s horn is further divided into four sections,
named CA1 to CA4. (CA stands for the Latin term for
Ammon’s horn, cornu Ammonis.)
Hebbian synapse and LTP require relatively
simultaneous firing called:
 Associativity A condition believed necessary for learning
in which the pre- and postsynaptic neurons are nearly
simultaneously active.
 Cooperativity A condition for the formation of LTP in
which several synapses onto the target postsynaptic
neuron must be simultaneously active.
 Both are needed for glutamate to influence postsynaptic
neuron
LTP and Spatial Memory
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Spatial memory, or an organism’s ability to map a
location
Episodic Memory and the Cerebral Cortex
 Patients with a damaged prefrontal areas of cortex
suffer from source amnesia.
Source Amnesia - memory loss for the circumstances in
which a particular fact or skill was learned.
 Anterior prefrontal cortex and the Costerior cingulate
cortex participate in retrieval of personal episodic
memories.
 we consult our personal experience to determine reality
 We utilize episodic memories to distinguish between
fantasy and reality
 When considering fantasy, ares semantic processing
shows the greatest activity because of violation of world
knowledge.
Short-Term Memory and the Brain
4 components
1. Central Executive
 Attentional aspects in STM
 Neural basis are dorsolateral prefrontal cortex (DLPFC)
and the anterior cingulate cortex (ACC)
 Lesions hinders the switching of attention to new things
Example: Card sorting experiment
2. Phonological Loop
3. Visuospatial Scratchpad
4. Episodic Buffer
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level of maturity in the prefrontal cortex is necessary
for short-term memory. And area of lesion (prefrontal)
affects STM
Large memory capacity = more activation of ACC; use
imagery of story telling
Less memory capacity = less activation of ACC; use
repetition, rehearsal to remember
The Striatum and Procedural Memory
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Straitum includes the basal ganglia (motor patterns)
and nucleus accumbens (reward for learning new
procedures)
Rats with lesion in the hippocampus experienced
lowered explicit memory but if the lesion is in the basal
ganglia procedural memory is affected
The Effects of Stress on Memory
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Freud believed that traumatic memories can become so
inaccessible that they are essentially lost or repressed
 PTSD - traumatic memories are vivid and intrusive
 the Yerkes-Dodson Law indicates that there's a sweet
spot for arousal levels that leads to optimal
performance. Too little arousal might lead to lack of
motivation or boredom, while too much can cause
stress and hinder performance. The key is finding the
right balance based on the task at hand.
 In this case, the amygdala LTP successfully processed
the emotional component of the stressful event, but the
hippocampus LTP (damaged by lack of oxygen) was
unable to encode the declarative details of the event.
Example: Man buried in the sand
 Stress affects the hippocampus, amygdala and the
functions normally carried out by the prefrontal cortex,
including coping skills, decision making, planning, and
multitasking.
 chemicals known as glucocorticoids, including cortisol,
are released during stress and increase the activity of
the amygdala
 Higher levels of cortisol are correlated with the
reporting of more false memories
 Propanolol, which blocks the effects of glucocorticoids
in the brain, might prevent the formation of traumatic
memories when administered immediately following a
traumatic event
Age & Memory
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As people age, decreased blood flow is observed in
many parts of the brain essential to memory and
cognition, especially in the frontal and temporal lobes.
However,
the aging brain also shows areas of increased activation.
suggest that these areas of increased activity represent
a reorganization of the brain that allows cognitive
performance to remain stable in spite of age-related
deficits in brain function