Conditioning, learning and

memory

Dr. Madanmohan. MD, DSc, FIAProfessor & Head, Department of Physiology

Mahatma Gandhi Medical College & Research Institute

Learning objectives

1. Define the terms conditioning, learning and

memory.

2. Give the differences between classical and

instrumental conditioning.

3. Describe the physiological mechanisms

involved in learning and memory.

4. Describe the types of memory.

5. Name the conditions that interfere with

consolidation of memory.

6. Give a brief description of senile dementia

and Alzheimer’s disease.

Conditioning: a learned response to a stimulus

that previously elicited little/no response.

Conditioned / adapted / accustomed.

Learning: ability to alter behavior /performance

as a result of experience.

Memory: ability to register, store and recall

ideas / images.

Conditioning

Conditioned reflex

Conditioned reflex:

A reflex response to a stimulus that previously

elicited little / no response

Conditioned response:

adapted, circumstanced, accustomed, different

Example: Going to class, temple festival, picnic.

Type I:

Classical conditioning of Pavlov.

Temporal pairing.

Type II:

Instrumental or operant conditioning.

Skinner (1904 – 1990). Response is “elicited”.

Classical (Pavlovian) conditioning

Food salivation Bell no salivation(US) (UR)

Bell food salivation ( Repeat / temporal pairing )

Bell x salivation

(CS) (CR)

Condtioned reflexes of higher order

Examples

UR CR• Food saliva Licking, chewing

• CV (visceral) Bio–feedback

• Foot shock (somatic)

• Sexual reflexes Sexual behaviour

Differences

UR: CR:

• Inborn Acquired

• Stable Unstable

• Subcortical Cortical

• All members of species Individual

Physiological basis

• Pairing/temporal association of 2 stimuli.

• Establishment of functional connections/

synapses.

• Summation of excitation & synaptic

facilitation.

• Protein synthesis.

Physiological significance

1. Habits.

2. Training, sports, skill.

3. Conditioned response to time.

4. Biofeedback: control of BP (yoga).

Adaptation/orientation to time/place/environment

Characteristics of conditioned response

1. Specificity:

2. Reinforcement:

Positive R: Pleasant stimulus/sti. of reward

area.

Negative R: Unpleasant reinforcement like

painful shock.

3. Inhibition:

Internal (extinction): CR not re-inforced and

response decreases.

External : CR abolished if there is disturbing

external stimulation after CS

Learning

Learning

Definition: ability to alter behavior or

performance as a result of experience.

Acquisition of knowledge, skill, attitude,

behavior.

Learning: acquisition. Memory: storage

Memory is essential for learning and the

two are closely linked.

Mechanism of learning(physiological basis)

• Cellular

• Synaptic

• Cortical

Cellular level

Rudimentary/no nervous system: vertebrates, unicellular

Simple learning behavior in flatworm:

shock curling(UR)

Light shock curling

Light curling(CR)

Synaptic level (subcortical)

Habituation/inhibition:

Loud sound startle.

Startle becomes less with repeated stimulation.

Repeated sti Ca++ transmitter.

(boring/neutral)

Learns to ignore:

e.g. mother & baby sleeping on railway platform.

Gradual decrease in response with repeated

non-noxious stimulus.. Is stimulus-specific

Facilitation or sensitization:

Repeated sti. Ca++ transmitter (strong/noxious)

Baby’s faint cry.

Resident doctor on duty.

Increased response to repeated/strong/noxious stimulus.

Facilitation & inhibition modify stereotyped

reflexes and responses

learning experiences.

Noxious stimuli increase organism’s

responsiveness to other neutral stimuli.

Cortical level

• Learning is more complex.

• Learning makes cortex thicker.

• Formation of new (functional) synapses.

• Intercortical transfer of memory through

corpus callosum and lower levels.

• Conditioning is associative learning.

• Habituation and facilitation are

non-associative learning.

Memory

Memory

Definition: ability to register, store and recall

ideas, images.

Learning Memory.(acquisition) (retaining)

The two are closely linked & difficult to dissociate.

without memory, no learning.

New learning increases horizon of memory.

Performance

Motivation

Interest attention learning

memory intelligence prajna

Memory: two types

1. Declarative (explicit): stated, unequivocal.

Conscious recall, recall a trip last wk.

2. Non-declarative (implicit): reflexive, understood.

Unconscious, automatic habit /skill

e.g., ride a bike.

Memory: types

Sensory memory or immediate memory.

Primary memory or short-term memory

Secondary memory or long-term memory

Declarative memory

1. Short term memory: a few sec to a few min.

Visual (after image), auditory (cough).

Remember a telephone number.

2. Long term/permanent memory: months-years

Recall your school function.

Consolidated, robust.

Mechanism of memory

Conditioning and learning memory.

Establishment in two stages.

Short term memory

1st stage, initial, reverberating circuit.

Sensory information stored in the circuit.

Modulation of synaptic transmission by

modification of ion channels.

Vulnerable / fragile. Retrieved or destroyed.

Long-term memory(consolidation of memory)

• Reverberating circuits are long/strong enough.

• Synthesis of proteins/neurotransmitters.

• Formation of new (functional) synapses.

• Structural changes in pre /post synapse.

• Facilitation of synaptic transmission.

Encoding is impaired by: head trauma, anesthesia,

hyperthermia, hypothermia, puromycin, ECT …..

Areas of brain

Widespread areas (holographic theory).

Categorical (left): logical, learning.

Representational (right): non–verbal, color.

Association areas: Wernicke’s, temporal, frontal.

Cerebellum: co-ordinates

Memory is impaired by

1. Hypoxia

2. Hypothermia

3. Insulin coma

4. General anesthesia

5. Head trauma, brain disease

6. Local chemicals: xylocaine, puromycin

7. Convulsions: high temperature, hyperthemia,

epilepsy, ECT, metrozol

Disorders of memory

Dementia: defect in learning, memory and

other intellectual functions.

Elderly (senile): >70 y: ~10%, >85 y: 20-50%

Organic brain disease, psychiatric, toxins,

vitamin B deficiency, disinterested & depressed.

Alzheimer’s disease: premature and progressive

aging and degeneration of brain.

Degeneration of cholinergic neurons,

cerebral atrophy.

Anterograde amnesia: unable to form new,

long- term memory.

Retrograde amnesia: unable to recall past

memory.

Drugs that facilitate memory

CNS stimulants: caffeine, nicotine, amphetamine.

Ayurvedic herbs: brahmi, mandukaparni.

Mechanism: Increase in excitability,

reverberation, consolidation.

Summary

• Conditioning

• Learning

• Memory