PT  - JOURNAL ARTICLE
AU  - Nimchinsky, Esther A.
AU  - Yasuda, Ryohei
AU  - Oertner, Thomas G.
AU  - Svoboda, Karel
TI  - The Number of Glutamate Receptors Opened by Synaptic Stimulation in Single Hippocampal Spines
AID  - 10.1523/JNEUROSCI.5066-03.2004
DP  - 2004 Feb 25
TA  - The Journal of Neuroscience
PG  - 2054--2064
VI  - 24
IP  - 8
4099  - http://www.jneurosci.org/content/24/8/2054.short
4100  - http://www.jneurosci.org/content/24/8/2054.full
SO  - J. Neurosci.2004 Feb 25; 24
AB  - The number of receptors opening after glutamate release is critical for understanding the sources of noise and the dynamic range of synaptic transmission. We imaged [Ca2+] transients mediated by synaptically activated NMDA receptors (NMDA-Rs) in individual spines in rat brain slices. We show that Ca2+ influx through single NMDA-Rs can be reliably detected, allowing us to estimate the number of receptors opening after synaptic transmission. This number is small: at the peak of the synaptic response, less than one NMDA-R is open, on average. Therefore, stochastic interactions between transmitter and receptor contribute substantially to synaptic noise, and glutamate occupies a small fraction of receptors. The number of receptors opening did not scale with spine volume, and smaller spines experience larger [Ca2+] transients during synaptic transmission. Our measurements further demonstrate that optical recordings can be used to study single receptors in intact systems.