Supporting Material Associated with the Manuscript Entitled:
Axons compensate for biophysical constraints of variable size to uniformize their action potentials
János Brunner; Antónia Arszovszki; Gergely Tarcsay; János Szabadics (2024)
The dataset is organized into folders. If the file structure is not visible, please switch the view from Table mode to Tree mode.
Folders:
- Figure S1_variable_local_capacitance_along_axons
A NEURON+Python simulation demonstrating local axon size-dependent variability along a reconstructed mossy fiber
- Figure S2 AP shapes in axon segments that form synapses and connecting parts
The folder contains four subfolders, each holding the anatomical data for a single experiment. Within each subfolder, you will find:
- The corresponding deconvolved confocal image stacks (*.nd2).
- A list of Bassoon-positive puncta (*.xlsx).
- The field of view for voltage imaging (VSD_FOV... .tiff).
- A summary file presenting the VSD-correlated analysis (*.tiff).
- Figure S3 Identification of axons patched in the DG originating from the supramammillary nucleus
The folder contains two subfolders, each holding the anatomical data (deconvolved confocal image stacks (*.nd2) and a summary file (*.tiff)) for a single experiment.
- Figure S4_Identification of axons patched in the DG originating from the hilar mossy cells
The folder contains two subfolders, each holding the anatomical data (deconvolved confocal image stacks (*.nd2) and a summary file (*.tiff)) for a single experiment.
- Figure S5_Identification of axons originating from the GABAergic CB1-receptor expressing cells
The folder contains two subfolders, each holding the anatomical data (deconvolved confocal image stacks (*.nd2) and a summary file (*.tiff)) for a single experiment.
::::::::::::::::::::::::::::::::ABSTRACT:::::::::::::::::::::::::::::::::::
Active conductances tune the kinetics of axonal action potentials (APs) to support specialized functions of neuron types. However, the temporal characteristics of voltage signals strongly depend on the size of neuronal structures, as capacitive and resistive effects slow down voltage discharges in the membranes of small elements. Axonal action potentials are particularly sensitive to these inherent biophysical effects because of the large diameter variabilities within individual axons, potentially implying bouton size-dependent synaptic effects. However, using direct patch-clamp recordings and voltage imaging in small hippocampal axons in acute slices from rat brains, we demonstrate that AP shapes remain uniform within the same axons, even across an order of magnitude difference in caliber. Our results show that smaller axonal structures have more Kv1 potassium channels that locally re-accelerate AP repolarization and contribute to size-independent APs. while they do not preclude the plasticity of AP shapes. Thus, size-independent axonal APs ensure consistent digital signals for each synapse within axons of same types.
(2024-09-02)
