Types of Memory (iconic memory) (7 bits for 30seconds)

Types of Long-Term Memory Explicit Implicit conscious recall learned skills personally experienced events general facts motor or cognitive activation of associations associative learning

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

Memory Areas Amygdala Caudate Hippocampus Visual Cortex

Types of Learning Associative Learning: Non-Associative Learning: Classical Conditioning (Pavlov) 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) Operant Conditioning (Skinner) Behavior is associated with rewards Reinforcement Punishment Non-Associative Learning:

Cellular Mechanism for Learning Hebbian Synapse: Frequent stimulation can change the efficacy of a synapse

Enrichment Protocol Impoverished Condition Enriched Condition

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

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