Cerebellar LTD

Cerebellar LTD

1. Decreased signalling

   • Not the opposite of hippocampal LTP

2. GABA neurotransimitter

3. Cells of the cerebellum

   • Mossy fibres come from motor cortex about the context of movement and also give info on sensory environment inwhich you perform the movement i.e. rocking boat, climbing a hill
     • Mossy fibres synapse onto Granule cells bifurcate into parallel fibres which run through the molecular layer of cerebellum
       • Parallel fibres form excitatory synapse with Purkinje cells and produces simple spikes
         • Purkinje Cells
           • Inferior olive in brainstem sends axon projections which wind around 1 Purkinje cell many times like ivy. Produce massive excitation
             • one-one relationship
             • provide Purkinje cell with an "error message"
             • Activation produces complex spikes (similar to heart ish)
           • Recieves info from two sources
           • Inhibitory synapse to Cerebelar nuclear cell (-) GABA
     • Glutamate (+)

4. Cerebellum as a 'pattern associator'

   • Pattern of parallel input produces a specific output down Purkinje cell
     • has to be a modifiable synapse to allow learning

5. purpose of cerebellum to learn motor skils

   • Purkinje cells learn patterns = execution of action
   • Climbing fibre input facilitates by acting as a 'teacher'

6. Marr-Albus theory: LTD is the mechanism for learning

7. Stimulating Purkinje cells

   • CNQX blocks AMPA receptors
   • high enough glu conc. will activate mGluR
     • IP£ production releases Ca from intracellular stores= red double peak
     • activate GPCR > PLC > IP3 > Ca release and CICR
       • PKC phosphorylates AMPA and internalises them
   • No NMDA-R

8. Stimulating Climbing fibre

   • broad general spike

9. Cerebellar LTD requires...

   • Combined input from Parallel Fibres and Climbing Fibres
     • Temporal sync
       • 1st: Climbing fibre i.e stimulus prior to the noxious stim
       • 2nd: Parallel fibre
       • CF teaches PF to elicit a response on its own
     • plasticity

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