Learning

LEARNING * Dr. Chintan Parmar- 3rd Year Resident- Dept. of Physiology- Govt. Medical College, Bhavnagar- Dt. : 4th April, 2013

Higher functions of CNS

Speech, language, learning, memory, intelligence, judgement

Role of PET scan & fMRI

Neurosurgical Procedures

Learning & Memory

Learning & Memory

Learning is acquiring new, or modifying existing, knowledge, behaviors, skills & values.

A characteristic of animals and particularly of humans is the ability to alter behavior on the basis of experience.

Learning is acquisition of the information that makes this possible & Memory is the retention and storage of that information.

Memory is the processes by which information is encoded, stored & retrieved.

Types of Learning Simple non-associative learning – single stimulus

Habituation Sensitization

Associative learning

Classical conditioning Operant conditioning

HabituationHabituation is an example of non-associative

learning in which there is a progressive diminution of behavioral response with repetative stimulus.

Molecular mechanism – Decrease in NT release at synapse due to inactivation of Calcium influx at the axonal endings ( channels inactivation )

Sensitization

Sensitization is opposite to habituation in which the progressive amplification of a response follows repeated administrations of a stimulus.

Molecular mechanism – Increased release of NT due to 3rd facilitatory interneuron – presynaptic fascilitation – release of serotonin – 2 receptors

Sensitization

Serotonin1st receptor – Gs – AC – cAMP – PKA – decrease

potassium current – prolongs AP – increased calcium influx – increased NT release

Vesicles mobilisation – exocytosis

Opens L type of calcium channels

2nd receptor – Go – PLC – DAG – PKC - Vesicles mobilisation & Opens L type of calcium channels

Sensitization

Associative learning

Associative learning is the process by which an association between two stimuli or a behavior and a stimulus is learned.

Classical – 2 stimuli

Operant – stimuli & behaviour

Classical conditioning

Classical conditioning involves repeatedly pairing an unconditioned stimulus ( US ) which evokes a reflexive response with another neutral stimulus which does not normally evoke the response (unconditioned response).

Following conditioning, the response occurs both to the US and to the other neutral stimulus now referred to as the conditioned stimulus ( CS ). The response to the CS is termed a conditioned response.

Pavlov ( Russia ) experiment.

Pavlov experiment

Pavlov experimentPrerequisites :

1. Alertness with good health

2. Timing

3. Duration of CS – overlap US

4. Type of US – not motor

Reinforcement

Internal Inhibition ( Extinction )

External Inhibition

Classical conditioning

Physiological basis – formation of new functional connections in CNS ( intracortical or subcortical )

Molecular basis – Presynaptic fascilitation by interneuron will increase after US activates sensory neuron – increased NT release

Operant conditioning

In operant conditioning a certain behavior is either rewarded or punished which results in an altered probability that the behavior will happen again or not.

Reward – Positive Reinforcement

Punishment – Negative Reinforcement

Operant conditioning

AppliedBiofeedback

Conditioning of visceral responses

Alteration of bowel movements, HR & BP

Rx of HT

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