Molecular & Cellular Bases Flashcards
What are the two main forms of learning that can be investigated?
Procedural - behaviour change/acquisition. Simple pathways that link sensations to movements. Easy to study.
Declarative - knowledge acquisition (mediated by the hippo). Difficult to study.
What are the two parts of procedural learning?
Non-associative learning - habituation, sensitisation.
Associative learning - classical conditioning, operant conditioning.
What is a habituation?
Decrease in the strength or occurrence of a behaviour due to the repeated exposure to the stimulus that produces that behaviour.
What is a sensitisation?
Increase in the strength or occurrence of a behaviour due to exposure to an arousing/noxious stimulus.
What are the main levels of analysis?
Molecular & cellular - behavioural & cognitive neuroscience.
With increased knowledge = increased ethical dilemma.
How did aplysia contribute to non-associative learning (invertebrate models of learning)?
Aplysia = snails.
Kandel intensively studied them.
Giant neurons that could be easily isolated to form mini brains.
Gil withdrawal - reflex in aplysia. Stimulation of the siphon leads to a protective/defence reflex to withdraw the gil. Only 2 neurons involved.
Snail learns and new synaptic connections are formed - LTM.
Where does habituation take place?
At synapse between sensory and motor neuron.
Neurotransmitter release at pre-synapse gets attenuated. Occurs at post-synapse - post-synapse neuron response gets weaker.
How do chemical synapses work?
- Vesicle docked at active zone.
- AP arrives, voltage gated Ca+ channels open.
- Exocytosis occurs - neurotransmitters released into cleft.
- Neurotransmitter caused transmitter-gated ion channels to open. Na+ rushes into cell - depolarisation.
- Used vesicles are recycled (endocytosis).
Where does sensitisation occur?
Sensory neuron and motor neuron synapse.
How does sensitisation occur?
- AP at terminal button of neutron L29 - release of serotonin.
- Serotonin receptors at terminal button of sensory neutron activated - cascade of molecular dynamics - activation of protein kinase A in sensory neuron.
- Protein kinase A blocks part of the K+ (potassium) channels in sensory neutron.
- Blocking of K+ channels. Prolonged action potentials at terminal button of sensory neuron.
- Longer APs - stronger influx of calcium into sensory neuron’s terminal button.
- More calcium influx = more vesicles will release NT into synaptic cleft between sensory + motor neurone.
- More NTs - stronger response at motor neuron.
Sensitisation shares the same neural mechanism with which process?
Classical conditioning.
Quantitative difference - classical > sensitisation.
More amplified neural response.
Who discovered classical conditioning?
Pavlov.
Who discovered operant conditioning?
Thorndike, Skinner.
How does classical conditioning in the aplysia work?
When CS and UCS are paired - Ca(2+) streams into terminal button of sensory neutron when cAMP is synthesised. Much more active protein kinase A than during sensitisation - more K+ channels blocked, longer AP, stronger response at motor neuron.
When does LTP occur in the hippocampus (vertebrate models of learning + memory).
LTP occurs with high frequency stimulation of Schaffer collaterals.