summation


Also found in: Dictionary, Thesaurus, Medical, Legal, Financial, Wikipedia.

summation

1. the act or process of determining a sum; addition
2. the result of such an act or process
3. US law the concluding statements made by opposing counsel in a case before a court

Summation

 

in physiology, the cumulative effect of several stimuli following one another in rapid succession (temporal summation) or occurring simultaneously (spatial summation) and arising in such excitable structures as receptors, neurons, and muscles.

Summation was first described in 1868 by I. M. Sechenov, who observed that under certain conditions of rhythmic stimulation there was a delay in the appearance and subsequent intensification of reflexes. Temporal summation occurs in the intervals between stimuli. These intervals are limited by the period of subthreshold or trace shifts in membrane potential toward depolarization, with development of excitation, or toward hyper-polarization, with development of inhibition. Temporal summation ensures that the duration of the reaction will be sufficient and that it can be maintained by the circular relationship between the neurons.

Spatial summation changes continuously and is manifested by the simultaneous excitation or inhibition of many neurons in different parts of the brain as well as of numerous synapses in a single neuron. Summation helps to intensify individual reactions and to coordinate the body’s reactions. In muscles, spatial summation intensifies contractions by increasing the number of excited motor units, that is, groups of fibers innervated by a single neuron. Temporal summation in muscles induces tetanus by uniting successive individual contractions.

A. N. KABANOV

References in periodicals archive ?
More information about Summation can be found at http://www.accessdata.com/products/ediscovery-litigation- support/summation.
AD Summation CaseVantage 6 boasts a long list of new stability and performance enhancements, as well as the following new features:
Trident Pro, coupled with CT Summation Discovery Cracker, will significantly reduce overall discovery processing costs.
In this paper, we define noncommutative bilateral basic hypergeometric series of type I and type II (over an abstract unital Banach algebra R) and prove, using functional equations, noncommutative extensions of Ramanujan's [sup.1][[psi].sub.1] summation. These generalize the noncommutative Q-binomial theorem of [14, Th.
The summation operator [SIGMA] means to add up the values of the variable beginning with the first value stated in the index, progressing one value at a time and ending with the last value in the index.
Sherman and Austin's chocolate chipchoices are an important first step in studying the ability of animals to perform operations on numbers, says Hank Davis of Guelph (Canada) University, but summation remains a murky concept.
Summation is also your chance to point out inconsistencies in the defense case.
where we sum over both i and j and require two summation signs.
Proof: Letting [S.sub.N] be the value of the summation, by induction it is seen that the equation for recursion, at stage M, is given by:
The mock theta functions were there and my simple summation identity in (9) was a tool, to give generating functions for the partial mock theta functions.