Physiology and the whole organism · Article

Graded response, fatigue and summation in reflex and nerve

Graded response, fatigue and summation are properties that separate a reflex arc from a bare nerve trunk. Sherrington set them out in 1906 as differences between the two kinds of conduction. Nerve follows stimulus strength closely and tires little. Reflex pathways need repeated impulses to get through, and they tire.²⁴⁵ Later authors looked for the electrical basis of these effects.⁷

Earliest held: 1890, James, W.
Most discussed in: The Integrative Action of the Nervous System, 1906
In the library: 247 passages in 25 works
Rewritten: 2026-10-05

Summation in behaviour

William James, in The Principles of Psychology (1890), collected examples in which stimuli too weak to act alone produce an effect when combined. His case from aphasia is one: a patient who cannot name an object that is only shown to them will name it if they touch it as well as see it.¹ James used such cases to make a general point about summation. He did not tie the idea to a single site in the nervous system.

Nerve compared with reflex

Sherrington, in The Integrative Action of the Nervous System (1906), made the contrast exact. He noted that the grading of effect by stimulus intensity is easier in the nerve trunk. In the nerve trunk the accuracy within a range of intensity was so good that some observers gave the ratio a mathematical form.² Waller found that a directly stimulated nerve followed the stimulus increment more closely than muscle stimulated through its nerve.³ For reflex arcs Sherrington listed resistance to a single impulse that a succession of impulses overcomes, called temporal summation.⁴ He also listed fatigability, against the comparative unfatigability of nerve trunks.⁵

Electrical correlates

J. C. Bose, in Comparative Electro-Physiology (1907), tied fatigue to the electrical response. In one of his typical cases the action current in an anisotropic organ was reversed because the excitability of one end was depressed by fatigue. W. M. Bayliss (1915) treated the effect of inadequate stimuli on nerve as a local effect left behind, as shown by Adrian and Lucas in 1912.⁶ R. S. Lillie (1923) noted that with excessive stimulation the return of the normal positivity is delayed or incomplete.⁷

Later network models

Modern work on non-neural tissue borrows the same vocabulary. Manicka and Levin (2019) modelled bioelectric networks with two layers of sigmoidal transformation. They compared this to neuronal cells, where nonlinear transformation of local dendritic potentials is followed by a second stage that sums the outputs.⁸

SourcesEach quotation was checked word for word against the passage it opens.

Aphasia shows many examples of summation. A patient who cannot name an object simply shown him, will name it if he touches as well as sees it, etc.James, W., 1890 · The Principles of Psychology, Vols. 1-2 · open at passage 188
The accuracy of grading within a certain range of stimulus-intensity is so remarkable that the ratio between stimulus-intensity and response-intensity has by some observers been assigned mathematical expression.Sherrington, C. S., 1906 · The Integrative Action of the Nervous System · open at passage 154
Waller finds the response in a nerve-trunk, directly stimulated, increase in much closer direct proportion to the increment of external stimulus than does the response of muscle to indirect stimulationSherrington, C. S., 1906 · The Integrative Action of the Nervous System · open at passage 154
considerable resistance to passage of a single nerve- impulse, but a resistance easily forced by a succession of impulses (temporal summation)Sherrington, C. S., 1906 · The Integrative Action of the Nervous System · open at passage 49
fatigability in contrast with the comparative unfatigability of nerve-trunksSherrington, C. S., 1906 · The Integrative Action of the Nervous System · open at passage 49
the local effect left behind by an inadequate stimulus to nerve, as shown by Adrian and Lucas (1912), seems to be a similar condition.Bayliss, W. M., 1915 · Principles of General Physiology · open at passage 1966
with excessive stimulation of any kind the return of the normal positivity is delayed or incomplete (Hermann and others).Lillie, R. S., 1923 · Protoplasmic Action and Nervous Action · open at passage 528
such a two-layer transformation is also found in neuronal cells, where the first stage involves nonlinear transformations of local dendritic potentialsManicka S, Levin M, 2019 · Modeling somatic computation with non-neural bioelectric networks · open at passage 8

Linked ideas

Electrical response of living tissuerelated to

Bose and Lillie read fatigue and summation through the electrical response of tissue to stimulation.

Resting membrane potentialprecursor of / follows

Lillie's account of delayed return of normal positivity points to membrane potential as the basis of graded and fatigued response.

Current of injuryrelated to

Bose described the action current as a positive or negative variation of the injury current, and fatigue could reverse it.

Habit and plasticityrelated to

Summation and fatigue show that repeated stimuli leave lasting traces in reflex pathways, a step toward habit.

Conditioned reflexrelated to

Reflex arcs that add up and tire are the setting in which conditioned reflexes were studied.

Homeostatic learning rules for gap junction couplingparallels

Manicka and Levin give non-neural networks layered nonlinear summation like that of neurons.

Chemical regulation of breathingrelated to

The depth of breathing follows the alveolar CO2 pressure, a graded response to stimulus level.

Differential susceptibility as a measure of metabolic rateparallels

Both treat differences in degree, not kind, as the basis of response to an external agent.

Excitation wave, conduction and the nerve impulse as a gradientrelated to

Concerns how the size of a response relates to the stimulus that starts the conducted change.

Local and reflex regulation of circulation and excretionrelated to

Bayliss's tonic stimulation and its inhibition show a response that rises and falls with the level of nerve impulses.

Multi-stimulus integration and behavioral priorityrelated to

In the planarian assay, changing signal strength changed which behavior won, so intensity governs priority.

Where it is discussedPassages matching grading of intensity, stimulus-response relation, action current, fatigue of reflex

1906	The Integrative Action of the Nervous System · Sherrington, C. S.	45
1907	Comparative Electro-Physiology: A Physico-Physiological Study · Bose, J. C.	42
1923	Protoplasmic Action and Nervous Action · Lillie, R. S.	28
1890	The Principles of Psychology, Vols. 1-2 · James, W.	23
1915	Principles of General Physiology · Bayliss, W. M.	21
1927	Conditioned Reflexes: An Investigation of the Physiological Activity of the… · Pavlov, I. P.	15
1902	Response in the Living and Non-Living · Bose, J. C.	13
1899	General Physiology: An Outline of the Science of Life · Verworn, M.	9
1926	A Bipolar Theory of Living Processes · Crile, G. W.	8
1906	Plant Response as a Means of Physiological Investigation · Bose, J. C.	7