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Learning and Memory (Synaptic plasticity = changes in the structure or…
Learning and Memory
Synaptic plasticity = changes in the structure or biochemistry of synapses that alters the strength of the synaptic connections.
LTP (Long-Term Potentiation) = the phenomenon by which EPSPs become stronger in a long-term, stable manner.
We can induced LTP if we stimulate the perforant path with high intensity, high frequency stimulation
Associative Long-term potentiation: The increase in synaptic strength that occurs in weak synapses when they are active right around the time when stronger inputs caused the postsynaptic neuron to spike.
Hebb's rule: Hypothesis proposed by Donald Hebb that the cellular basis of learning involves the strengthening of synaptic connections that are active when the postsynaptic neuron fires an action potential.
- This is known as: "Fire together, wire together... more strongly than before. The synaptic connection does have to initially exist"
Hippocampal formation = Forebrain structure of temporal lobe, constituting an important part of limbic system.
Includes the CAI, II, III, as well as dentate gyrus and subiculum.
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Pre-synaptic Plasticity
NO (Nitric oxide synthase): Enzyme responsible for the production of nitric oxide (often released from a post-synaptic synapse)
Several experiments suggest that NO may be retrograde messenger that contributes to formation of LTP.
LTD (Long-term depression): Long-term decrease in the strength of the connection between 2 neurons (synaptic strength). Low-frequency activity in the inputs to a quiet neuron (in the synapses) can decrease the strength of the active synapses. LTD is often mediated by endocannabinoid signaling, from postsynaptic neuron to presynaptic neuron.
EPSPs = Excitatory postsynaptic potentials and membrane depolarizations used by evoked activity in some number of inputs (synapses).
Psychology terminology
UR (unconditioned response):a behavior that spontaneously, naturally occurs in response to a U.S.
CS (Conditioned Stimulus): an initially meaningless, neutral stimulus that becomes associated with an unconditioned stimulus (e.g. a bell or light that can be used to predict food delivery)
E.g. the CS can be a tone
US (Unconditioned Stimulus): something that has inherent value to an animal, like a food reward or an electric shock. There is no learning (conditioning) involved with an unconditioned stimulus. It is what it is. (US = aversive)
CR (Conditioned Response): a behavior that occurs in response to a CS.
This behavior is often (but not always) similar to the UR that follows the US that was associated during the training with the CS.
Nature of Learning
Associative Learning: Typically includes most forms of stimulus-stimulus and stimulus-response learning.
Probably is responsible for all learning.
Basically, when you perceive a stimulus, it either makes you more likely to think of something else (stimulus-stimulus) or it makes you more likely to respond in some way (stimulus-response)
Non-Associative Learning: Often refers to the phenomena of habituation and sensitization, which are when you start to respond differently to a stimulus just because you have perceived (seen it, smelled it, etc) some number of times before.
(E.g. if a stimulus is neutral and without predictive value, animals habituate to it)
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