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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
THANK YOU
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