LTD

Question 1

What are the two types of long term depression

Answer 1

Depotentiation - removal of previous potentiation

LTD de novo - No previous potentiation

Question 2

What is the Albus Marr model

Answer 2

Climbing fibre input indicates a motor error and weakens the parallel fibre to purkinje cell synapse

Question 3

What is the mechanism of LTD in the cerebellum

Answer 3

Doesn’t involve NMDA receptors
Depolarization of the climbing fibre - Ca influx at pre synapse - Causes increased glutamate release
glutamate acts on AMPA receptors at the postsynaptic neuron - increased Na influx postsynaptically
Also acts on GPC metabotropic glutamate receptor - activates phospholipase C - IP3 DAGS - DAGS activates PKC - phosphorylates GluR2 AMPA receptor - Both mechanisms required in order for LTD to occur

Question 4

What is the process of hippocampal LTD

Answer 4

Low EPSP causes only partial unblocking of magnesium from NMDA receptors - Only partial binding of glutamate so only partial influx of calcium - Small calcium influx activates more phosphatase action over kinase - dephosphorylation of AMPA receptors reduces activity and endocytosis of AMPA receptors - reducing synapses connection - LTD - can reduce previously potentiated synapse