1. A stimulant. 2. That which can elicit or evoke action (response) in a muscle, nerve, gland or other excitable tissue, or cause an augmenting action upon any function or metabolic process. [L. a goad]
- adequate s. a s. to which a particular receptor responds effectively and that gives rise to a characteristic sensation; e.g., light and sound waves that stimulate, respectively, visual and auditory receptors.
- aversive s. a noxious s. such as an electric shock used in aversive training or conditioning. SEE ALSO: aversive training.
- conditioned s. 1. a s. applied to one of the sense organs ( e.g., receptors of vision, hearing, touch) which are an essential and integral part of the neural mechanism underlying a conditioned reflex; See classical conditioning, higher order conditioning. 2. a neutral s., when paired with the unconditioned s. in simultaneous presentation to an organism, capable of eliciting a given response.
- discriminant s. a s. which can be differentiated from all other stimuli in the environment because it has been, and continues to serve as, an indicator of a potential reinforcer.
- heterologous s. a s. that acts upon any part of the sensory apparatus or nerve tract.
- heterotopic s. any electrical activation from an abnormal locus.
- homologous s. a s. that acts only on the nerve terminations in a special sense organ.
- inadequate s. SYN: subthreshold s..
- liminal s. SYN: threshold s..
- maximal s. a s. strong enough to evoke a maximal response.
- square wave stimuli electrical stimulation in which the intensity of the current is brought suddenly to a given level and maintained at that level until it suddenly is cut off; this type of s. is particularly useful in obtaining a strength-duration curve.
- subliminal s. SYN: subthreshold s..
- subthreshold s. a s. too weak to evoke a response. SYN: inadequate s., subliminal s..
- supramaximal s. a s. having strength significantly above that required to activate all of the nerve or muscle fibers in contact with the electrode; used when response of all the fibers is desired.
- threshold s. a s. of threshold strength, i.e., one just strong enough to excite. SEE ALSO: adequate s.. SYN: liminal s..
- train-of-four s. a method for measuring magnitude and type of neuromuscular blockade, based upon the ratio of the amplitude of the fourth evoked mechanical response to the first one, when four supramaximal 2-Hz electrical currents are applied for 2 s to a peripheral motor nerve.
- unconditioned s. a s. that elicits an unconditioned response; e.g., food is an unconditioned s. for salivation, which in turn is an unconditioned response in a hungry animal. See classical conditioning.

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stim·u·lus 'stim-yə-ləs n, pl -li -.lī, -.lē
2) an agent (as an environmental change) that directly influences the activity of living protoplasm (as by exciting a sensory organ or evoking muscular contraction or glandular secretion) <a visual \stimulus>

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n. (pl. stimuli)
any agent that provokes a response, or particular form of activity, in a cell, tissue, or other structure, which is said to be sensitive to that stimulus.

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stim·u·lus (stimґu-ləs) pl. stimґuli [L. “goad”] any agent, act, or influence that produces functional or trophic reaction in a receptor or in an irritable tissue.

Medical dictionary. 2011.

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  • stimulus — [ stimylys ] n. m. • 1795; mot lat. sc.; cf. a. fr. stimule « aiguillon » et fig. (XVIe); de stimuler ♦ Physiol. Cause externe ou interne capable de provoquer la réaction d un système excitable. ⇒ excitant. « lorsque tel organe [...] se contracte …   Encyclopédie Universelle

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  • stimulus — stimulus, stimulant, excitant, incitement, impetus can all mean an agent that arouses a person or a lower organism or a particualr organ or tissue to activity. Only the first three words have definite and common technical use. Stimulus, in this… …   New Dictionary of Synonyms

  • Stimulus — may refer to:*Sha Stimuli, a brooklyn based rapper. *Stimulus (band), an experimental band *Stimulus (physiology), something external that influences an activity *Stimulus (psychology), a concept in behaviorism *Input to a system in other fields… …   Wikipedia

  • Stimulus — Stim u*lus, n.; pl. {Stimuli}. [L., for stigmulus, akin to L. instigare to stimulate. See {Instigare}, {Stick}, v. t.] 1. A goad; hence, something that rouses the mind or spirits; an incentive; as, the hope of gain is a powerful stimulus to labor …   The Collaborative International Dictionary of English

  • STIMULUS — apud Terentium Phormione, Act. 1. sc. 2. v. 28. Nam quae inscitia est Adversum stimulos calces, supple iactare? κέντρον est Aeschylo, Agamemn. v. 1620. Πρὸς κέντρα μὴ λάκτιζε et Scriptori sacro Actorum c. 9. versu 5. et c. 26. v. 14. ubi eadem… …   Hofmann J. Lexicon universale

  • stimulus — plural stimuli, 1680s, originally as a medical term, something that goads a lazy organ (often the male member), from Mod.L. stimulus goad (see STIMULATION (Cf. stimulation)). General sense is from 1791. Psychological sense is first recorded 1894 …   Etymology dictionary

  • stimulus — stȉmulus m DEFINICIJA term. djelovanje neke vrste energije na osjetne receptore; podražaj ETIMOLOGIJA lat. stimulus ≃ stimulans: poticajan ← lat. stimulare …   Hrvatski jezični portal

  • Stimŭlus — (lat.), 1) spitziges Ding, Stachel; bes. 2) eiserne Spitze an einem Stab, womit Fuhrleute u. Landbauer die Zugthiere antrieben; 3) eiserne Spitzen, welche da ausgestreut wurden, wo man sich eines Angriffs der Reiterei versah, vgl. Fußangeln; 4)… …   Pierer's Universal-Lexikon

  • stimulus — I noun activator, animator, arouser, calcar, catalyst, catalytic agent, cause, drive, encouragement, excitant, fillip, goad, impetus, impulse, incentive, incitamentum, incitement, inducement, influence, inritamentum, motivating force, motive,… …   Law dictionary

  • Stimulus — Stimulus,der:1.⇨Antrieb(1)–2.⇨Reiz(1) …   Das Wörterbuch der Synonyme

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