Bursting

Bursting is a rapid signaling mode in neurons whereby clusters of two or more action potentials (spikes) are emitted as a single signaling event. A burst of two spikes is called a doublet, three spikes - triplet, four - quadruplet, etc. Burst mode is thought to be useful for signaling important events and routing information in the brain. In general, there are two types of bursting:

1. Input-driven bursting, where strong excitatory inputs produce a rapid activation and burst of action potentials
2. Intrinsic bursting, where voltage-gated ion channels intrinsic to the neuron convert brief suprathreshold inputs into long-lasting bursts of action potential output.

Some types of neurons are able to respond to current input by emitting an all- or non-burst response. This burst usually consists of a short phase of repeated action potentials, at a frequency of up to 350 Hz. This is followed by a prolonged refractory period. In contrast, neurons that fire tonically respond with action potentials at a rate proportional to the input current.

Most mathematical models of bursting can be written in the singularly perturbed form

$$

begin{matrix} dot{x} = f(x, y) & mbox{(fast spiking)} dot{y} = mu g(x, y) & mbox{(slow modulation)} end{matrix} where x is the fast variable, a vector that simulates fast spiking of the neuron, and y is the slow variable, a vector that modulates spiking activity. A topological classification of bursters relies on the bifurcations of the fast subsystem (variable x) when the slow subsystem (variable y) is treated as a parameter.

The subiculum is an example of a brain region where the rapid transition between bursting and single-spiking is important for routing information out of the hippocampus.

Bibliography

• (2005) Action potential burst mode transition mechanism, PLoS Biology, 3(6):e175
• (2005) Switching Signals in the Brain, PLoS Biology, 3(6):e210
• Cooper, Donald C. (2002) Significance of action potential bursting, Neurochemistry International Volume 41, Issue 5
• Izhikevich, Eugene M. (2006) Bursting Scholarpedia, p.1401
• Izhikevich, Eugene M. (2007) Dynamical Systems in Neuroscience: The Geometry of Excitability and Bursting. The MIT Press.

People

• Don Cooper