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branching point

Also known as: branching points

Facts (12)

Sources
Branching morphology determines signal propagation dynamics in ... nature.com Nature Aug 21, 2017 12 facts
formulaWilfrid Rall defined the geometric ratio (GR) for branching points as GR = (da^(3/2)) / (sum(dj^(3/2))), where da is the diameter of the mother branch and dj are the diameters of the daughter branches.
claimStockbridge demonstrated that at branching points with short and long daughter branches, only the first spike of an adjacent pair invades the long branch, while both spikes propagate into the short branch.
claimIn the 'Blockage' activity pattern, all spikes fail to pass the branching point of an axon.
claimIn the 'Trains' activity pattern, all spikes pass the branching point of an axon uninterruptedly.
claimFor a geometric ratio (GR) of 1, there is a perfect impedance match, allowing action potentials to smoothly cross branching points.
claimWhen the geometric ratio (GR) of an axon is less than 1, action potentials cross branching points with slight changes in shape and velocity; when the geometric ratio is greater than 1, action potentials cross with a delay that scales exponentially with the ratio.
claimModulations in the frequency of action potential trains can result from spike failures along the axon and through branching points.
claimExisting literature on branched axons typically uses the geometrical ratio (GR) as the single geometrical parameter to determine activity coding at branching points, which results in symmetric responses.
measurementAt intermediate stimulus frequencies (51–146 Hz, based on parameters in Supplementary Table S1), branched axons exhibit symmetric firing patterns between daughter branches, even when the branching points are geometrically asymmetric.
referenceKhodorov et al. and Parnas et al. extended the analysis of neuronal activity across branching points to include several spike series.
claimIn the 'Intermitted trains' activity pattern, several consecutive spikes pass the branching point followed by a single failure, or a single spike passes followed by a failure.
claimFor stimulus frequencies higher than 146 Hz in branched axons, some spikes fail to propagate in the mother branch before reaching the branching point.