Download Learning and Memory

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
Reinforcement
is any procedure that increases the response
Positive Reinforcement
adding or presenting a stimulus that increases the response
Negative Reinforcement
removing a stimulus that increases the response
Punishment
is any procedure that decreases the response
Types of Memory
(iconic memory)
(7 bits for 30seconds)
Types of Long-Term Memory
Explicit
Implicit
learned
skills
conscious
recall
personally
experienced
events
general
facts
motor
or
cognitive
activation
of
associations
associative
learning
Memory Processes
Step 2
Step 1
Step 3
Retrieval
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
HM
Implicit Memory Intact
No Explicit Memory
Hippocampus is Critical for
Spatial Learning
Rats must remember which doors have the reward
Caudate Nucleus Critical for
Response 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
Memory Areas
Amygdala
Caudate
Hippocampus
Visual Cortex
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 single
action potential
Slope of
the EPSP
(one
characteristic
measure of an
action potential)
baseline response
potentiated response
Hippocampus has a three synaptic pathway
Stimulate one area (mossy fibers) and record the action potentials in another (CA1)
Stimulate multiple times to get a baseline response
Once a stable baseline is established give a brief high frequency stimulating pulse
Use the same stimulating pulse as in baseline but now see a potentiated response
This potentiated response can last hours, days, or even weeks (LTP)
Normal
Synaptic
Transmission
Glutamate Channels:
NMDA
Mg2+ block
no ion flow
AMPA
Na+ flows in
depolarizes cell
LTP
Induction
With repeated activation
the 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