Skip to main page content
Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 1999 May 13;399(6732):151-5.
doi: 10.1038/20187.

Synaptic Calcium Transients in Single Spines Indicate That NMDA Receptors Are Not Saturated

Affiliations

Synaptic Calcium Transients in Single Spines Indicate That NMDA Receptors Are Not Saturated

Z F Mainen et al. Nature. .

Abstract

At excitatory synapses in the central nervous system, the number of glutamate molecules released from a vesicle is much larger than the number of postsynaptic receptors. But does release of a single vesicle normally saturate these receptors? Answering this question is critical to understanding how the amplitude and variability of synaptic transmission are set and regulated. Here we describe the use of two-photon microscopy to image transient increases in Ca2+ concentration mediated by NMDA (N-methyl-D-aspartate) receptors in single dendritic spines of CA1 pyramidal neurons in hippocampal slices. To test for NMDA-receptor saturation, we compared responses to stimulation with single and double pulses. We find that a single release event does not saturate spine NMDA receptors; a second release occurring 10 ms later produces approximately 80% more NMDA-receptor activation. The amplitude of spine NMDA-receptor-mediated [Ca2+] transients (and the synaptic plasticity which depends on this) may thus be sensitive to the number of quanta released by a burst of action potentials and to changes in the concentration profile of glutamate in the synaptic cleft.

Comment in

Similar articles

See all similar articles

Cited by 106 articles

See all "Cited by" articles

Publication types

Feedback