All summary questions- classical conditioning Flashcards
Strategy for studying neural basis of memory?
– Need to pick a simple task to start with
– Suitable simple task?
– Eyeblink conditioning has been well studied.
– Simplest version: delay conditioning of nictitating membrane response (NMR)
Where in brain are the plastic synapses that mediate this conditioning?
– In people, medial temporal lobe damage prevents formation of new long-term memories, but has little effect on eyeblink conditioning
– In rabbits the forebrain not needed for delay NMR conditioning
– But both electrophysiological and lesion studies implicate the cerebellum
How to establish circuitry underlying delay NMR conditioning?
– Use standard neuroscience techniques
• Anatomy
• Electrophysiology
• Manipulation
Circuitry can be broken down into 5 parts
– Unconditioned reflex pathway
– Output of anterior interpositus nucleus controlling the conditioned response
– Output of eyeblink region of cerebellar cortex controlling the anterior interpositus nucleus
– Eyeblink region receives information about conditioned stimulus via mossy fibres
– Eyeblink region receives information about unconditioned stimulus via climbing fibres
What are the main cell types in cerebellar cortex?
– Purkinje, granule, Golgi, stellate, basket.
How are they connected?
– See circuit diagram
Where are the potential sites of plasticity?
– Purkinje cell dendrites receive information about the CS from parallel fibres, and about the US from climbing fibres
– Cells in anterior interpositus nucleus also receive these inputs
How is eyeblink conditioning related to other ‘cerebellar’ tasks?
– They are all mediated by the same basic neural circuit
General theories of cerebellar function: what task do they model?
– Making sure movements are accurate
What methods (algorithms) have been proposed?
– Supervised learning: an error signal makes movements bigger or smaller as required
How does learning theory work in cerebellum?
– Mossy fibres convey input information
– Climbing fibres convey error information
– Latter used to depress synapses contributing to error (LTD)
Can this general theory be applied to eyeblink conditioning?
– In principle yes. In practice?
Where are the plastic synapses in NMR conditioning?
– Modelling predicts the synapses between granule cells and Purkinje cells
Evidence: are plastic synapses in cerebellum or brainstem?
– Several lines of evidence strongly point to the cerebellum