Lecture 25 Flashcards by Teruka Taketa

What is Procedural memory?

Skills and association largely unavailable to conscious mind

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What is Declarative memory?

Available to conscious mind. Can be encoded in symbols and language

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How long does immediate memory last?

Few seconds

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How long does short-term memory last?

Seconds or minutes

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What is a type of short-term memory which has a limited capacity?

Working memory

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How long does long-term memory last?

Days, months, years

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How can long-term memories be triggered?

Random events

e. g. olfactory systems
- smells can trigger events that happened many years ago

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What does the pre-frontal cortex store?

Working memory

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Which structure is essential for converting short to long term memory and stores declarative memory?

the hippocampus

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What does the amygdala do?

Multiple, processed sensory inputs (smell)

Implicit/emotional/learnt fear

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What does the cerebellum do?

Procedural, sensorimotor

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What do hippocampal lesions cause?

Memory loss

Not able to remember declarative memories

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What are two theories in which London taxi drivers have larger hippocampuses?

Hippocampus grows with experience

People have larger hippocampus which shrinks over time when lacking stimulation

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What is the structure of the hippocampus?

Three layered cortex
Unusual development
 - layers wrap around one another
 - invagination occurs then fusion
Contains different cells
Choroid plexus is the main output
 - neurons project to different parts of the brain

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How are long-term memories stored?

Distributed - changes all over the brain

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What is the theory of Reverberating circuits?

Memory is not static and stored but some form of constant activity in neurons which can be triggered by some other events

What is the Hebbian synapse concept?

Activity modifiable plastic synapse
Memory is a change in synapse between two neurons
Synapse can become weaker or stronger depending on activity

What is Facilitation?

Synapse become stronger

What is Depression?

Synapse become weaker

What are merits of Depression?

Can lead to different acquisition or memory, so not necessarily “forgetting”
Can be presynaptic, postsynaptic, and depends on different types of memory

What processes affect memory and synaptic plasticity?

Short term:
Ca availability/vesicle depletion
Long term:
Sustained

What affects Long-term potentiation (LTP)?

LTP in hippocampal slices (and elsewhere)

CA1, CA3: connected with each other with a synapse

What is post-“tetanic” LTP?

Can record from CA1 and CA3 neurons

- stimulate electrode and record synaptic potentials

What do high frequency bursts do?

1000Hz
neurons starts changing
Amplitude of EPSP will increase
Can last for years (or even decades!)
Specific to input
 e.g. Different stimulatory electrodes
When only CA1 is stimulated CA3 doesn't change
 - long term specifity

What causes paired LTP?

Simultaneous depolarization of both neurons trigger long term potentiation - decrease in EPSP - can last for a long time Associativity - link between stimuli e.g. Pavlovian dog - mechanisms that explains associative form of memory (simultaneous depolarization)

Where does Long term depression (LTD) occur?

Cerebellum

What happens when LTD occurs?

Decrease in amplitude of EPSP Certain stimulation on neurons decrease EPSP and amplitude Not simultaneous

What is an animal model for memory investigations?

Aplysia californica | - different invertebrates experience variety of memories

How does Aplysia californica act as a good animal model?

``` Gill withdrawal reflex - animal doesn't like to be touched - withdraws gills into body Have big neurons (easy to record) Simple nervous system (Humans: billions of neurons, Aplysia: thousands of neurons) ```

What does Gill habituation reflex show?

Habituation - keep touching gills then animal stops withdrawing gilk Short-term sensitization Long-term sensitization

What are two types of conditioning?

Classical (pavlovian) and operant (skinner)

How would short-term sensitization show in Aplysia?

Repeated gentle stimuli to siphon causes reduced gill withdrawal Pair single tail pinch (aversive) with siphon touch - Re-establish siphon reflex - Short-term 60 mins

How would long-term sensitization show in Aplysia?

Repeated pairing of siphon touch and tail pinch | Non-habituating siphon/gill reflex

What is needed in LTP and LTD?

Require receptor activation (glutamate, serotonin) - post-synaptic - AMPA receptors - NMDA receptors Second messengers (cAMP, Ca) Involve biochemical and structural pre and post synaptic changes

How are AMPA receptors involved in LTP and LTD?

Ionotropic regulated by glutamate Open as long as glutamate is bound Responsible for depolarization

How are NMDA receptors involved in LTP and LTD?

Ca channel | Flow of Ca is important

What is considered to be important in memory formation?

Altered synaptic responsivity

What is needed to long-term changes?

Require protein phosphorylation changes in early stages | Require protein synthesis for late stages

How does LTP occur?

Evidence suggests often a post-synaptic event Most indicate a critical role for Ca Involves trafficking of AMPA receptors to the post-synaptic membrane