Wednesday, March 19, 2008

More about Oscillations - Part II:

In reference to More About Oscillations Part I:


*most of the oscillators in the brain belong to the family of relaxation oscillators

*a single neuron is a very typical pulse type of oscillator: if the neuron is depolarized, if certain channels that prevent the neuron from habituation or from adaptation are blocked, then the neuron will spike forever

*there is one period (action potential) and a longer period, the "in between", the charging phase or the incremental phase

*if large numbers of these neurons are considered together and their mean or average field activity measured, they can become very sinusoid - their collective behavior looks like a harmonic oscillator

*the elements that are critical in generating the oscillations are made up from relaxation oscillators: however they are tied together in a monolithic form, such that they form a harmonic oscillator

*it has features of both - the good features of both: they can be perturbed effectively, but they are also good timekeepers.

A useful INPUT/OUTPUT feature:

*relaxation oscillators can be separated into "input phase" and "output phase"
output phase means when an effect is going out; in the faucet example - the drop of water is the "output"

*the incremental (charging) phase is the "input", the phase in which water accumulates, the phase when the system or the oscillator can be perturbed

*separation of the input/output highlights the relatively long time when the oscillator can be perturbed, or input can be put into the system

*the internal mechanisms of the oscillator determine when the output occurs

*when effects are combined/synchronized, outputs can be enhanced, can become more than just the sum of the parts

*output phase includes refractory phase, when perturbation has no effect

No comments: