Learning and Memory Flashcards
What is learning?
Acquisition of information
What is memory?
Storage of learned information
What is recall?
Reacquisition of stored information
What is the engram?
Physical embodiment of a memory i.e. the physical and chemical changes from storing a memory
What are the main types of memory? (4)
- Procedural/declarative memory
- Implicit/explicit memory
What is procedural memory?
Skills that are largely unavailable to conscious mind e.g. riding a bike
What is declarative memory? (2)
- Factual information that is available to the conscious mind
- Can be encoded in symbols/language and transmitted between individuals
What is explicit memory?
Memory that can be consciously recalled
What is implicit memory?
Memory that can’t be consciously recalled
What are the 3 types of implicit memory?
- Procedural memory
- Classical conditioning
- Priming
What is priming?
When one stimulus influences the response to subsequent stimuli
What are the advantages of using ‘simple’ systems to study memory? (5)
- Neuronal size (easy to record from)
- Circuit complexity
- Temperature dependence mutations
- Mapping tools (genetic manipulation)
- Fewer ethical issues
What are the simple forms of memory? (2)
- Habituation
- Sensitisation
What is habituation?
Decrease in the amplitude of the response as the stimulus is repeated
What is sensitisation?
Increase in the amplitude of the response as the stimulus is repeated
What are examples of habituation in humans? (4)
- Habituation of eye blink reflex
- Habituation of repetitive non-harmful stimulus presentation
- Habituation of visual attention
- Habituation of emotional response
How can habituation be studied?
Gill withdrawal reflex in Aplysia
What is habituation of the gill withdrawal reflex? (2)
- Touch of water jet causes gill withdrawal
- Repeating the stimulus reduces the reflex
How does habituation happen in the gill withdrawal reflex? (2)
- Sensory neuron in the siphon skin forms a synapse with a motor neuron which connects to the gill muscle
- When the stimulus is repeated, the presynaptic sensory neuron response stays the same but the postsynaptic motor neuron response decreases = habituation
What is the molecular mechanism of habituation?
Reduced neurotransmitter release due to depletion of the readily releasable pool (RRP) so the amplitude of each response gets smaller
What is the readily releasable pool (RRP)?
The vesicles containing neurotransmitter that are in the active zone and are immediately released following depolarisation
What is the proximal pool?
The vesicles containing neurotransmitter which diffuse to the active zone to become the RRP
What is the reserve pool?
The vesicles containing neurotransmitter which are furthest away from the active zone
What is sensitisation of the gill withdrawal reflex?
The gill withdrawal reflex is a lot stronger when preceded by a noxious stimulus
How does sensitisation happen in the gill withdrawal reflex? (3)
- L29 sensory neuron senses the noxious stimulus and releases serotonin
- Activates 5-HT receptor on the first sensory neuron, activates adenylyl cyclase which produces cAMP, activates pkA
- pkA phosphorylates and inactivates K+ channels = longer presynaptic neuron depolarisation so more vesicles are released onto the motor neuoron
What is the molecular mechanism of sensitisation?
Serotonin-ergic feedback from an additional sensory neuron
What is associative learning? (2)
- Association of a conditioned stimulus with a non-conditioned stimulus e.g. Pavlov’s dogs
- Timing is critical
What is the difference between sensitisation and associative learning?
The 2 stimuli need to happen at the same time in associative learning but no in sensitisation
What is the mechanism of associative learning? (2)
- Same mechanism as sensitisation but when the L29 neuron releases serotonin onto the sensory neuron the sensory neuron is already depolarised from the other stimulus
- The Ca2+ influx in the sensory neuron stimulates adenylyl cyclase even more than the serotonin on its own so even more vesicles are released
What are the 3 main protein kinases?
- pKA
- camKII
- pKC
What activates pKA?
cAMP
What activates camKII?
Ca2+
What activates pKC?
Diacylglycerol (DAG)
What happens in the late stages of memory formation? (2)
- Changes in the nucleus
- MAPK can enter the nucleus and phosphorylate transcription factors changing gene expression, allows for long-term response