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. Author manuscript; available in PMC: 2015 Dec 30.
Published in final edited form as: Neuropharmacology. 2012 Jul 11;64:13–26. doi: 10.1016/j.neuropharm.2012.06.051

Fig. 1.

Fig. 1

Indirect modulation of NMDARs. (A) Schematic representation of some ways in which NMDAR function can be regulated indirectly. Neurotransmitters, and other neuronal regulators, can facilitate NMDAR function by augmenting the “Hebbian depolarization” and by intracellular regulation. NMDARs are important for (B) synaptic transmission (C) the induction of LTP and (D) the induction of LTD. Note that NMDARs contribute considerably to the synaptic response during high frequency synaptic transmission; in this example the NMDAR-EPSP has summated with the AMPAR-EPSPs (shaded yellow) to fire several action potentials (adapted from Herron et al, 1986). LTP is induced by a brief period of high frequency stimulation whilst LTD is induced by a prolonged period of low frequency stimulation. Key: Different types of receptor populations are shown by a colour-coded symbol. Inward current via AMPARs and NMDARs (carried mainly by Na+) contributes to the Hebbian depolarization and is shown by a red arrow. Outward current (carried mainly by the movement of K+ (GABAB) out of the cell or Cl- (GABAA) into the cell) opposes the Hebbian depolarization and is depicted by a blue arrow. Ca2+ entry is shown by the grey arrow and Mg2+ by a black circle.