L7 - Cerebellum and Motor Learning Flashcards
What percentage of neurons in the brain are found in the cerebellum?
Over 50%
What inputs information into the cerebellum?
Mossy fibres and climbing fibres
Where do the inputs into the cerebellum feed into?
Purkinje cells
How many mossy fibres are needed to activate one purkinje fibre?
200
How many climbing fibres are needed to activate one purk`inje fibre?
1
The output from the cerebello cortex projects to what?
Deep cerebellar nuclei.
If someone had a lesion to their cerebellum, what would they suffer from?
Inability to make accurate movements.
What is ataxia?
A loss of co-ordination and skill
What is hypermetria?
An overshoot of fine/precision movement. Gross movement is fine, but the accuracy of the finer movement lacks - means putting finger to nose is more difficult.
What is intention tremor?
A tremor that is induced from movements, or when focussing on a certain task.
What might happen should cerebellum damage occur?
- Ataxia
- Hypermetria
- Intention tremor
- Nystagmus, balance, speech deficits
- Cerebellar affective disorder: executive, emotional and personality issues.
Where does the cerebellar nuclei project/output to?
- Motor and pre-motor cortex
- Spinal cord
What is the gain?
How much input leads to how much output - calibration process between sensory and motor systems.
What happens when there is an error, for example, retinal slip, in the VOR?
An error signal transmits through climbing fibres to the Purkinje cells, leading to depression of the synaptic connections. This means that the cell fires less the next time it happens, meaning a stronger response next time (as the Purkinje cells have an inhibitory effect)
How do climbing fibres initiate LTD?
They fire a teaching signal which causes calcium ions to enter.
Explain the role of calcium ions in LTD.
Calcium ions internalise AMPA receptors and puts them into stores/recycles them.
Why is LTD an associative mechanism?
Parallel fibres have to be active/firing at the same time, or during a specific time frame, that the climbing fibres’ teaching signals are active.
Spikelets give us an indication of what occurring?
Error in our system, in terms of an event occurring that we did not expect.
What do climbing fibres cause
Simple Spikes and complex spikes.
What do simple spikes represent?
Signals being sent to Purkinje cells from mossy fibres - indicating that no error has occurred.
What do complex spikes represent?
Signals being sent to Purkinje cells from climbing fibres- indicating error in the system.
Would adults or children be faster at visuomotor adaptation (prism glasses) and why?
Adults, as their cerebellum is more developed.
What is the main role of the cerebellum?
Sensory motor integration and prediction.
Where do the climbing fibres and their teaching signals originate from?
Inferior olive
What is the large output from the cerebellum to the prefrontal lobe for?
- Potential roles in cognitive tasks such as planning, attention and language.
- Links to autism, affective disorders and dyslexia.
What is the Marr-Albus model of learning?
Concerns changing the strength of connections between parallel fibres and purkinje cells through long term depression.
