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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 (temporal summation).
Temporal summation: When a single synapse inputs that are close together in time, their potentials are also added together. Thus, if a neuron receives an excitatory postsynaptic potential, and then the presynaptic neuron fires again, creating another EPSP, then the membrane of the postsynaptic cell is depolarized by the total sum of all the ...
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.
The summation theorem suggests this does not necessarily have to be the case. The flux summation theorem also suggests that there is a total amount of flux control in a pathway such that if one step gains control another step most lose control. Plot of a phenotype, such as a flux, as a function of enzyme level.
In mathematics, summation by parts transforms the summation of products of sequences into other summations, often simplifying the computation or (especially) estimation of certain types of sums. It is also called Abel's lemma or Abel transformation , named after Niels Henrik Abel who introduced it in 1826.
This list of mathematical series contains formulae for finite and infinite sums. It can be used in conjunction with other tools for evaluating sums. Here, is taken to have the value
Low retinal summation results in high visual acuity, with individual photoreceptor cells sending their own signals. High retinal summation yields high sensitivity to low light levels, where the signal is summed before reaching the brain—presumably advantageous when the signals reaching individual photoreceptor cells are weak.
Currently, it is only available for Mathematics and offered by the exam board Edexcel. They were introduced in 2002, in response to the UK Government's Excellence in Cities report, as a successor to the S-level examination, and aimed at the top 10% of students in A level tests. They are assessed entirely by external examinations.