Classical Conditioning PDF

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Learning & Memory - ClassicalConditioning Lecture 2 NotesLecture 2 Part 1 Basic Concepts & Role Of CerebellumRussian physiologist Ivan Pavlov, in 1890’s performed research into the salivation of dogs in response to being fed. He discovered classical conditioning which is now also kno...

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Learning & Memory - Classical Conditioning Lecture 2 Notes Lecture 2 Part 1 Basic Concepts & Role Of Cerebellum

Russian physiologist Ivan Pavlov, in 1890’s performed research into the salivation of dogs in response to being fed. He discovered classical conditioning which is now also known as pavlovian conditioning. Dogs produced saliva in just the anticipation of being fed rather than the act of being fed. What is classical conditioning? Associate an involuntary response and a stimulus. Involves learning a new behaviour through the process of association. What is operant conditioning? Associate a voluntary behaviour and a consequence.

Unconditioned Stimuli (UCS) Unconditioned Response (UCR)

Before conditioning or associative learning, stimuli are unconditioned and evoke unconditioned response. An example would be the Norovirus which is the UCS and nausea would be the UCR. Neural stimuli do not evoke a response.

What happens during conditioning or associative learning?

A neutral stimulus is paired with an unconditioned stimulus. The neural stimuli now becomes a conditioned stimulus. What happens after conditioning or associative learning? The conditioned stimulus evokes a conditioned response. What is conditioned taste aversion? Involves the avoidance of certain food following a period of illness after consuming that food.

The Cerebellum Also known as the little brain. Makes up 10% of total brain volume, 50% of its neurones. Plays a central role in certain forms of classical conditioning. Located under the two hemispheres. Damaging/silencing of the cerebellum prevents eye-blink conditioning.

How The Cerebellar Cortex Is Organised? The distinct layers are the molecular layer, purkinje cell layer (output layer), granular layer (input layer)

What are mossy fibre inputs? Convey information about the intended movement including the state of the body at the time and the state of the environment. Contact golgi cells and granule cells. Carry a huge array of sensory motor information that can either excite purkinje cells through parallel fibres or inhibit them via interneurones.

What are parallel fibres?

The axonal extensions of granule cell and each fibre makes single synapses on hundreds of thousands of purkinje cells.

Cerebellar Cortex Organisation Diagram

Parallel fibres and molecular layer interneurones input onto the Purkinje cells. The strength of their inputs can be modulated through synaptic plasticity. Plasticity is regulated through climbing fibre inputs. In this way purkinje cells can learn to respond to a very specific pattern of sensorimotor activity.

Give an example of a form of classical conditioning: Eye-blink conditioning. What is eye-blink conditioning? A tone which is a conditioned stimulus, paired with a puff of air to the eye which is an unconditioned stimulus to elicit an eye blink which is a conditioned response.

A conditioned stimulus is presented shortly before an unconditioned stimulus that elicits an eye blink, the unconditioned response. This information^ was taken from the website below. https://www.sciencedirect.com/topics/veterinary-science-and-veterinarymedicine/eyeblink-conditioning

Diagram Illustrating Eye-Blink Conditioning Before Conditioning

What happens in the cerebellum before conditioning? Purkinje cells normally function to inhibit eye closure. The tone which is the conditioned stimulus is encoded via mossy fibre input but initially has no marked effect on Purkinje cell activity. The air puff which is the unconditioned stimulus results in a climbing fibre response and results in eye-blink. The tone alone is not enough to make the rabbit blink.

Diagram Illustrating Eye-Blink Conditioning During Conditioning.

What happens in the cerebellum during conditioning (tone-air puff pairing)? Association of the tone and the air-puff causes a weakening of the tone evoked Parallel Fibre to Purkinje cell input and a strengthening of the molecular layer interneurone to Purkinje cell input.

Diagram Illustrating Eye-Blink Conditioning After Conditioning.

What happens in the cerebellum after conditioning? The net result is a reduction in Purkinje cell firing when the tone sounds leading to disinhibition of the circuitry responsible for eye closure. Interfering with this cerebellar learning prevents acquisition of the Conditioned Stimulus. The conditioned stimulus, the tone, is enough to make the rabbit blink.

Associative Learning: Association and strengthening of tone paired with air-puff.

What is behavioural extinction? The weakening of associations that are not reinforced.

Behaviour Extinction Repeated activation of the conditioned stimulus, the tone, leads to a loss of the conditioned response which is the eye blink response. The tone begins to indicate the absence of the air puff. This is depicted in the graph below.

Summary of Lecture 2 Part 1

Classical conditioning involves the pairing and subsequent association of a neural stimulus and an unconditioned stimulus. After learning, a conditioned stimulus evokes a conditioned response. Cerebellar learning is involved in eye-blink conditioning. Weakening of learnt associations is known as extinction....