PT  - JOURNAL ARTICLE
AU  - CongJian Zhao
AU  - Elena Dreosti
AU  - Leon Lagnado
TI  - Homeostatic Synaptic Plasticity through Changes in Presynaptic Calcium Influx
AID  - 10.1523/JNEUROSCI.6636-10.2011
DP  - 2011 May 18
TA  - The Journal of Neuroscience
PG  - 7492--7496
VI  - 31
IP  - 20
4099  - http://www.jneurosci.org/content/31/20/7492.short
4100  - http://www.jneurosci.org/content/31/20/7492.full
SO  - J. Neurosci.2011 May 18; 31
AB  - Chronic perturbations of electrical activity within neural circuits lead to compensatory changes in synaptic strength collectively termed homeostatic synaptic plasticity. The postsynaptic mechanisms underlying these modifications have been characterized in some detail, but the presynaptic mechanisms that alter the efficiency of evoked neurotransmitter release are less clear. To investigate the role of presynaptic calcium influx, we have combined the use of two fluorescent proteins in cultured hippocampal neurons: a calcium reporter localized to synaptic vesicles, SyGCaMP2, and a reporter of vesicle fusion, SypHy. We find that a decrease in the activity of the network causes an increase in the amount of calcium entering the synaptic bouton in response to an action potential and an increase in the probability of vesicle fusion. Homeostatic changes in release probability varied as the third power of calcium influx. These results indicate that changes in the number and/or function of presynaptic calcium channels are major determinants of homeostatic changes in synaptic strength.