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Basic ways that neurons can interact with each other when converting input to output. Summation, which includes both spatial summation and temporal summation, is the process that determines whether or not an action potential will be generated by the combined effects of excitatory and inhibitory signals, both from multiple simultaneous inputs (spatial summation), and from repeated inputs ...
In mathematics, the Fejér kernel is a summability kernel used to express the effect of Cesàro summation on Fourier series. It is a non-negative kernel, giving rise to an approximate identity . It is named after the Hungarian mathematician Lipót Fejér (1880–1959).
Temporal summation means that the effects of impulses received at the same place can add up if the impulses are received in close temporal succession. Thus the neuron may fire when multiple impulses are received, even if each impulse on its own would not be sufficient to cause firing.
Since the Gibbs phenomenon comes from undershooting, it may be eliminated by using kernels that are never negative, such as the Fejér kernel. [12] [13]In practice, the difficulties associated with the Gibbs phenomenon can be ameliorated by using a smoother method of Fourier series summation, such as Fejér summation or Riesz summation, or by using sigma-approximation.
According to temporal summation one would expect the inhibitory and excitatory currents to be summed linearly to describe the resulting current entering the cell. However, when inhibitory and excitatory currents are on the soma of the cell, the inhibitory current causes the cell resistance to change (making the cell "leakier"), thereby ...
With the more usual convention = /, the first equation becomes () =, and the upper limit of integration on the third equation should be extended to , so that the condition 3 above should be ∫ δ ≤ | t | ≤ π | k n ( t ) | d t → 0 {\displaystyle \int _{\delta \leq |t|\leq \pi }|k_{n}(t)|\,dt\to 0} as n → ∞ {\displaystyle n\to \infty ...
Of particular importance is the fact that the L 1 norm of D n on [,] diverges to infinity as n → ∞.One can estimate that ‖ ‖ = (). By using a Riemann-sum argument to estimate the contribution in the largest neighbourhood of zero in which is positive, and Jensen's inequality for the remaining part, it is also possible to show that: ‖ ‖ + where is the sine integral
Borel summation requires that the coefficients do not grow too fast: more precisely, a n has to be bounded by n!C n+1 for some C. There is a variation of Borel summation that replaces factorials n! with (kn)! for some positive integer k, which allows the summation of some series with a n bounded by (kn)!C n+1 for some C.