Phase resetting in neurons
The periods of these oscillations can vary depending on the biological system, with examples such as: (1) neural responses can change within a millisecond to quickly relay information; (2) In cardiac and respiratory changes that occur throughout the day, could be within seconds; (3) circadian rhythms may vary throughout a series of days; (4) rhythms such as hibernation may have periods that are measured in years.
[8][10] A phase response curve can be calculated by noting changes to its period over time depending on where in the cycle the input is applied.
[5] In order to model the behavior of firing neural circuits, the following is calculated to generate a PRC curve and its trajectory.
[8][3][11][12] Numerous research has suggested two primary assumptions that allow the use of PRCs to be used to predict the occurrence of synchrony within neural oscillation.
The first assumption claims that coupling between neurons must be weak and requires an infinitesimally small phase change in response to a perturbation.
[8][3][14] The second assumption assumes coupling between neurons to be pulsatile where the perturbation to calculate PRC should only include those inputs that are received within the circuit.
The weak coupling also induces the claim that many cycles must occur prior to convergence of oscillators to phase lock to lead to synchronization.
Research has shown that specific changes in the topology of neural networks and their increase in synaptic strength can move into hyper-excited states.
Diseases such as epilepsy demonstrate how synchrony amongst neural networks must be highly regulated to prevent asynchronous activity.
The study of neural regulation could help to outline methods to reduce symptoms of asynchronous activity such as that observed in epilepsy.
Due to synchronization within the gamma-frequency range has been shown to be followed by phase resetting of theta oscillations when phase-locked by a stimulus.
[14][19] Theta phase precession is a phenomenon observed in the hippocampus of rats and relates to the timing of neural spikes.
