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Lecture 16

PSYC 211 Lecture Notes - Lecture 16: Entorhinal Cortex, Perforant Path, Synaptic Plasticity


Department
Psychology
Course Code
PSYC 211
Professor
Yogita Chudasama
Lecture
16

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PSYC211 Lecture 16 - Mar. 12
What Is Learning and Memory:
Learning refers to the process by which experiences change our nervous system. Learning can:
Involve specific relations between stimuli in the environment
Involve recognition and categorization of objects and situations
Involves information about events in the world
Involve skilled actions
Memory refers to the process that encodes, stores and retrieves the learning experience. Memories:
Can be transient or durable
Can be consciously (explicitly) declared or involve implicit procedures
Have a personal frame of reference
Permits a form of time-travel
Are not equally vulnerable to disease and disruption
Habituation is a Simple Form of Learning:
The aplysia is an invertebrate sea slug with a a simple nervous system (20,000 neurons)
The Aplysia has a large gill for respiration, and a siphon through which it expels water
If the siphon is lightly touched, the gill withdraws reflexively
Repeated touching with a tactile stimulus reduces the magnitude of the reflex until the Aplysia ignores the touch stimulus
This waning of sensitivity to repeated stimulation is known as habituation
Associative Learning:
In associative learning, the experimenter arranges a relationship between two events
Learning is the ability to learn to perform a behaviour in the presence of a particular stimulus
This type of learning involves connections between circuits involved in perception and those involved in movement
The resulting behaviour can be a reflexive response (e.g. Salivation or eyeblink) or a complicated sequence of previously
learned movements
Two major categories of associative learning:
Classical conditioning
Instrumental conditioning
Associative Learning: Classical Conditioning
In classical (Pavlovian) conditioning, a stimulus that previously
had no effect on behaviour becomes able to evoke a reflexive
‘conditioned’ response
The procedure involves the repeated pairing of two stimuli
Neural Circuit of Classical Conditioning:
We assume:
The UCS is detected by a single neuron in the somatosensory
system
The CS is detected by a single neuron in the auditory system
The CR is controlled by a single neuron in the motor system
When action potential reaches synapse T, the EPSP is too weak to make the
neuron fire
Synapse P is a strong synapse because a blink is a defensive reflex
For conditioning, the CS must be followed almost immediately by the UCS
The Hebb Rule:
The Hebb Rule states that the cellular bassi of learning involves the
strengthening of a synapse that is repeatedly active when the postsynaptic
neuron fires
Associative Learning: Instrumental Conditioning
In instrumental (operant) conditioning, the animal adjusts its behaviour
according to the consequences of that behaviour
If the learned behaviour is followed by favourable consequences, it will be strengthened (more likely to occur). If the
behaviour is followed by negative consequences, it will be weakened (less likely to occur)
The procedure involves the association between a stimulus and a response (but also the response and the outcome/reward)
3
Associative Learning: Classical Conditioning
!In classical (Pavlovian) conditioning, a stimulus that previously had
no effect on behaviour becomes able to evoke a reflexive
‘conditioned’ response.
!The procedure involves the repeated pairing of two stimuli.
Neutral
stimulus
Unconditioned
stimulus
Unconditioned
response
+
Tone Air Puff Eye Blink
+
During Conditioning/training
After Conditioning
Tone Eye Blink
Conditioned
stimulus
Conditioned
response
Neural Circuit of Classical Conditioning
!We assume:
- The UCS is detected by a
single neuron in the
somatosensory system.
-The CS is detected by a
single neuron in the auditory
system.
-The CR is controlled by a
singe neuron in the motor
system.
(UCS)
(CS)
(CR)
!When action potential reaches synapse T, the EPSP is too weak to
make the neuron fire.
!Synapse P is a strong synapse because a blink is a defensive reflex.
-For conditioning, the CS must be followed almost immediately by the
UCS.
3
Associative Learning: Classical Conditioning
!In classical (Pavlovian) conditioning, a stimulus that previously had
no effect on behaviour becomes able to evoke a reflexive
‘conditioned’ response.
!The procedure involves the repeated pairing of two stimuli.
Neutral
stimulus
Unconditioned
stimulus
Unconditioned
response
+
Tone Air Puff Eye Blink
+
During Conditioning/training
After Conditioning
Tone Eye Blink
Conditioned
stimulus
Conditioned
response
Neural Circuit of Classical Conditioning
!We assume:
- The UCS is detected by a
single neuron in the
somatosensory system.
-The CS is detected by a
single neuron in the auditory
system.
-The CR is controlled by a
singe neuron in the motor
system.
(UCS)
(CS)
(CR)
!When action potential reaches synapse T, the EPSP is too weak to
make the neuron fire.
!Synapse P is a strong synapse because a blink is a defensive reflex.
-For conditioning, the CS must be followed almost immediately by the
UCS.
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