Nanoscale dendritic shaft constrictions shape synaptic integration in fine caliber principal neuron dendrites

Abstract Traditionally, theoretical studies typically described dendritic morphology as optimized for efficient synaptic voltage transfer from spines to the soma, implemented as a tubular design respecting Rall’s 3/2 rule for impedance matching at branch points. Here, we reveal that this view is an oversimplification. Using three high-resolution imaging techniques, we demonstrate that dendrites in cortical and hippocampal neurons contain nanoscale constrictions, comparable in diameter to spine necks. We provide theoretical and experimental evidence that these constrictions partition the dendrite into distinct electrical compartments, significantly shaping dendritic integration of synaptic potentials. Competing Interest Statement The authors have declared no competing interest. Funder Information Declared DFG, FOR2715 Copyright The copyright holder for this preprint is the author/funder, who has granted bioRxiv a license to display the preprint in perpetuity. It is made available under a CC-BY 4.0 International license.