Magic. Magic. LTP. LTD. High/Correlated activity. Low/uncorrelated activity. High NMDA-R activation. Moderate NMDA-R activation. High Calcium. Moderate Calcium. LTP. LTD. What changes during synaptic plasticity?
K vesicles, Pr – prob of release
Are there other possible reasons for change in PPR?
Phosphorylation state of Gultamate receptors is correlated with LTP and LTD
GluR1-4, functional units are heteromers, probably composed of 4 subunits, probably composes of different subtypes.
Many are composed of GluR1 and GluR2
Protein Phosphorylation with LTP and LTD
Phosphorylation at s831 and s845 both increase conductance but in different ways
LTD- dephosphorylation at ser 845 with LTP and LTD
Lee et al. 2000
LTP- phosphorylation at ser 831 with LTP and LTD
Activity dependent insertion and removal and its dependence on Phosphorylation
Malinow, Malenka 2002 dependent.
There are two trafficking pathways: dependent.
1- Short, in which there is constant plasticity independent trafficking. But dephosphorylation at ser 880 on GluR2 might still trigger LTD.
2- Long, in which phosphorylation triggers LTP.
Note – Phosphorylation also increases conductance directly
Calcium through dependent.
For calcium channels the more precise formulation is to use the GHK equation (See Johnston and Wu pg: )
However, for simplicity we will use the simple ‘Ohmic’ formulation:
t the GHK equation (See Johnston and Wu pg: )
NMDA receptor kinetics- sum
of two exponents
Show calcium transients at low and high postsynatic voltage. the GHK equation (See Johnston and Wu pg: )
Talks about NMDA-R as a coincidence detector
A brief summary of the signal transduction pathway leading from Calcium to Phosphorylation/ Dephosphorylation
Summary from Calcium to Phosphorylation/ Dephosphorylation