Dynamics of dendritic spines and their afferent terminals: spines are more motile than presynaptic boutons.
Previous work has established that dendritic spines, sites of excitatory input in CNS neurons, can be highly dynamic, in later development as well as in mature brain. Although spine motility has been proposed to facilitate the formation of new synaptic contacts, we have reported that spines continue to be dynamic even if they bear synaptic contacts. An outstanding question related to this finding is whether the presynaptic terminals that contact dendritic spines are as dynamic as their postsynaptic targets. Using multiphoton time-lapse microscopy of GFP-labeled Purkinje cells and DiI-labeled granule cell parallel fiber afferents in cerebellar slices, we monitored the dynamic behavior of both presynaptic terminals and postsynaptic dendritic spines in the same preparation. We report that while spines are dynamic, the presynaptic terminals they contact are quite stable. We confirmed the relatively low levels of presynaptic terminal motility by imaging parallel fibers in vivo. Finally, spine motility can occur when a functional presynaptic terminal is apposed to it. These analyses further call into question the function of spine motility, and to what extent the synapse breaks or maintains its contact during the movement of the spine.
Deng
Jinbo
J
Department of Neuroscience, Brown University, Providence, IR 02912, USA.
Dunaevsky
Anna
A
D000818:Animals; D002465:Cell Movement / Q000502:physiology*; D002531:Cerebellum / Q000502:physiology* / Q000648:ultrastructure; D049229:Dendritic Spines / Q000502:physiology*; D049452:Green Fluorescent Proteins; D051379:Mice; D036641:Microscopy, Fluorescence, Multiphoton; D017729:Presynaptic Terminals / Q000502:physiology*; D011689:Purkinje Cells / Q000648:ultrastructure; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D013194:Staining and Labeling; D013569:Synapses / Q000502:physiology*
C073804:FM1 43; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds; D049452:Green Fluorescent Proteins