April 8th, 2003
Tuesday - 4:00 pm in Swain West 238
Speaker: Alan Fine, National Institute for Medical Research, Mill Hill, London UK and Dalhousie University Faculty of Medicine, Halifax NS Canada
Title: Optical Studies of Calcium Signaling, Transmission and Plasticity at Individual Hippocampal Synapses
Abstract:
Using fluorescent Ca²⁺ indicators and laser-scanning microscopy, transmission can be monitored at individual synapses in rat hippocampal slices and slice cultures. We have observed significant and functional Ca²⁺-induced Ca²⁺ release from internal stores on both sides of the synapse, and have also found that transient, synaptically-evoked depletion of Ca²⁺ from the synaptic cleft contributes to synaptic depression. Using synaptically-evoked Ca²⁺ transients in dendritic spines to carry out optical quantal analysis of transmission at individual synapses before and after the induction of LTP or LTD, we find that that both forms of plasticity are expressed, at least in part, through graded changes in the probability of transmitter release. Expression of LTP or LTD does not require formation or retraction of spines.