Characterization of MSB synapses in dissociated hippocampal culture with simultaneous pre- and postsynaptic live microscopy
PLoS ONE. 2011-10-20; 6(10): e26478
DOI: 10.1371/journal.pone.0026478
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Multisynaptic boutons (MSBs) are presynaptic boutons in contact with multiple
postsynaptic partners. Although MSB synapses have been studied with static
imaging techniques such as electron microscopy (EM), the dynamics of individual
MSB synapses have not been directly evaluated. It is known that the number of MSB
synapses increases with synaptogenesis and plasticity but the formation,
behavior, and fate of individual MSB synapses remains largely unknown. To address
this, we developed a means of live imaging MSB synapses to observe them directly
over time. With time lapse confocal microscopy of GFP-filled dendrites in contact
with VAMP2-DsRed-labeled boutons, we recorded both MSBs and their contacting
spines hourly over 15 or more hours. Our live microscopy showed that, compared to
spines contacting single synaptic boutons (SSBs), MSB-contacting spines exhibit
elevated dynamic behavior. These results are consistent with the idea that MSBs
serve as intermediates in synaptic development and plasticity.