Cell type-specific structural plasticity of axonal branches and boutons in the adult neocortex.
We imaged axons in layer (L) 1 of the mouse barrel cortex in vivo. Axons from thalamus and L2/3/5, or L6 pyramidal cells were identified based on their distinct morphologies. Their branching patterns and sizes were stable over times of months. However, axonal branches and boutons displayed cell type-specific rearrangements. Structural plasticity in thalamocortical afferents was mostly due to elongation and retraction of branches (range, 1-150 microm over 4 days; approximately 5% of total axonal length), while the majority of boutons persisted for up to 9 months (persistence over 1 month approximately 85%). In contrast, L6 axon terminaux boutons were highly plastic (persistence over 1 month approximately 40 %), and other intracortical axon boutons showed intermediate levels of plasticity. Retrospective electron microscopy revealed that new boutons make synapses. Our data suggest that structural plasticity of axonal branches and boutons contributes to the remodeling of specific functional circuits.
Howard Hughes Medical Institute, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
Vincenzo
V
De Paola
Anthony
A
Holtmaat
Graham
G
Knott
Sen
S
Song
Linda
L
Wilbrecht
Pico
P
Caroni
Karel
K
Svoboda
D000704:Analysis of Variance; D000818:Animals; D003952:Diagnostic Imaging / Q000379:methods; D049452:Green Fluorescent Proteins / Q000235:genetics; D021621:Imaging, Three-Dimensional / Q000379:methods; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D046529:Microscopy, Electron, Transmission / Q000379:methods; D008953:Models, Anatomic; D008954:Models, Biological; D019579:Neocortex / Q000166:cytology* / Q000648:ultrastructure; D016501:Neurites / Q000648:ultrastructure; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000145:classification* / Q000166:cytology* / Q000648:ultrastructure; D017729:Presynaptic Terminals / Q000648:ultrastructure; D018800:Thy-1 Antigens / Q000235:genetics; D013997:Time Factors
D018800:Thy-1 Antigens; D049452:Green Fluorescent Proteins