Types of Learning

Associative Learning:

•Classical Conditioning•Behavior is associated with paired stimuli

•unconditioned stimulus (UCS) yields an unconditioned response (UCR)•a neutral stimulus (NS) is paired with the unconditioned stimulus (UCS)•until the UCS alone (now the CS) yields a conditioned response (CR)

•Ivan Pavlov

•Operant Conditioning•Behavior is associated with rewards

•Reinforcement•Punishment

•B. F. Skinner

Classical Conditioning

Operant Conditioning

Reinforcementis any procedure that increases the response

Positive Reinforcementadding or presenting a stimulus that increases the response

Negative Reinforcementremoving a stimulus that increases the response

Punishmentis any procedure that decreases the response

Types of Memory

(7 bits for 30seconds)

(iconic memory)

Types of Long-Term Memory

Explicit Implicit

consciousrecall

learnedskills

personallyexperienced

events

generalfacts

motoror

cognitive

activationof

associations

associativelearning

Step 1

Step 2

Step 3

Retrieval

Memory Processes

Where is Memory Stored?Brain Impairment lead us to clues about learning and memory

•HM•Extreme seizures forced the removal of:

•medial basal regions of the temporal lobe (bilaterally)•most of the amygdala (bilaterally)•all of the hippocampus (bilaterally)

•Result:•Retrograde amnesia

•loss of some past memories•Anterograde amnesia

•loss of the ability to form new memories

Hippocampus is critical for the formation of new memories

Implicit Memory Intact

No Explicit Memory

HM

Hippocampus is Critical for Spatial Learning

Rats must remember which doors have the reward

Caudate Nucleus Critical forResponse Recognition Memory

Must turn in same direction to get reward (remembers its own response)

Visual Cortex is Critical for Sensory Perception

Rat must choose object that doesn’t match sample

Visual CortexCaudate HippocampusAmygdala

Memory Areas

Cellular Mechanism for Learning

Hebbian Synapse:Frequent stimulation can change the efficacy of a synapse

Enrichment Protocol

Impoverished Enriched

Quantifying Dendritic Arborization

Neurobiological Changes via Learning

Dendritic changes:•Increased dendritic arborization•Increased dendritic bulbs

Synaptic changes:•More neurotransmitter release•More sensitive postsynaptic area•Larger presynaptic areas•Larger postsynaptic areas•Increased interneuron modulation•More synapses formed•Increased shifts in synaptic input

Physiological changes: •Long-Term Potentiation•Long-Term Depression

Hippocampal Brain Slicing

Long-Term Potentiation (LTP)

each triangle represents a singleaction potential

Slope of the EPSP

(one characteristic measure of an

action potential)

Hippocampus has a three synaptic pathwayStimulate one area (mossy fibers) and record the action potentials in another (CA1)Stimulate multiple times to get a baseline responseOnce a stable baseline is established give a brief high frequency stimulating pulseUse the same stimulating pulse as in baseline but now see a potentiated responseThis potentiated response can last hours, days, or even weeks (LTP)

baseline response potentiated response

Normal Synaptic

TransmissionGlutamate Channels:

NMDAMg2+ blockno ion flow

AMPANa+ flows indepolarizes cell

LTP Induction

With repeated activationthe depolarization drives the Mg2+ plug out of the NMDA channels

Ca2+ then rushes in through the NMDA channels

Ca2+ stimulates a retrograde messenger to maintain LTP

Ca2+ also stimulates CREB to activate plasticity genes

LTP-induced Neural Changes

Learning Requires Protein Synthesis!

Anisomycin: (protein synthesis inhibitor) blocks long term memory