Conditioned reflex salivary secretion in man.
ABSTRACT Human subjects have been conditioned to secrete saliva in response to sounding a buzzer and switching on a light. Orange juice injected onto the dorsum of the tongue was used as the unconditioned stimulus during the conditioning sequences. Negative results obtained in the early experiments of the present series, and by other workers, have been attributed to failure to obtain a discrete secretory response with each conditioning stimulus. Pre-formed conditioned reflexes were also demonstrated in response to the sight or suggestion of food although these responses were small and not consistent.RésuméDes sujets ont été conditionnés pour sécréter de la salive en allumant une lumière et en entendant une sonnerie. Du jus d'orange, placé sur le dos de la langue, sert de stimulus inconditionné pendant les phases du conditionnement. Les résultats négatifs, observés au cours de recherches antérieures par les auteurs et d'autres chercheurs, ont été mis en rapport avec l'incapacité d'obtenir une réponse sécrétoire discrète avec chaque stimulus conditionné. Des réflexes conditionnés préformés sont aussi mis en évidence à la vue ou par l'évocation de nourriture bien que ces réponses soient faibles et non constantes.ZusammenfassungVersuchspersonen wurden dazu angeleitet, Speichel als Reaktion auf des Geräusch eines Summers und das Einschalten von Licht zu sezernieren. Auf den Zungenrücken gespritzter Orangensaft wurde als nichtbedingter Reiz während der konditionierenden Übungen benützt. Negative Ergebnisse bei den ersten Versuchen dieser Reihe und von anderen Autoren waren darauf zurückzuführen, daβ es nicht gelang, eine diskrete sekretorische Reaktion bei jedem bedingten Reiz zu erhalten. Vorgeformte bedingte Reflexe wurden auch als Reaktion auf das Sehen oder das Sich-vorstellen von Nahrung nachgewiesen, obwohl diese Reaktionen gering und nicht einheitlich waren.
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ABSTRACT: It is commonly stated that smell elicits a parotid salivary reflex in humans. However, this assumption seems to be supported only by experiments in which either a lemon or an irritating odour has been used as the primary stimulus. In this study six pleasant odours, chocolate, vanilla, peppermint, beef, tomato and lemon, were administered to ten subjects. Air was passed through a solution of the stimulant and the resultant odour was administered to the subject via a face mask. Unilateral parotid saliva was collected via a Lashley cup and salivary flow was measured using an instantaneous flowmeter sensitive to flows as low as 0.008 ml min-1. Citric acid, lemon juice, chocolate and distilled water were also delivered to the subjects at increasing concentrations. At low concentrations none of these stimuli significantly increased the parotid salivary flow above resting levels. However, an increase in salivary flow was seen when lemon juice or odourless citric acid was sniffed or delivered to the subject at high concentrations, causing irritation in the nasal cavity and/or the back of the throat. Our results suggest that there is no true olfactory-parotid salivary reflex in humans, and that acidic stimuli can cause irritation with a concomitant increase in the salivary flow.Experimental Physiology 06/1991; 76(3):347-55. · 2.79 Impact Factor
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ABSTRACT: Secretion of saliva to aid swallowing and digestion is an important physiological function found in many vertebrates and invertebrates. Pavlov reported classical conditioning of salivation in dogs a century ago. Conditioning of salivation, however, has been so far reported only in dogs and humans, and its underlying neural mechanisms remain elusive because of the complexity of the mammalian brain. We previously reported that, in cockroaches Periplaneta americana, salivary neurons that control salivation exhibited increased responses to an odor after conditioning trials in which the odor was paired with sucrose solution. However, no direct evidence of conditioning of salivation was obtained. In this study, we investigated the effects of conditioning trials on the level of salivation. Untrained cockroaches exhibited salivary responses to sucrose solution applied to the mouth but not to peppermint or vanilla odor applied to an antenna. After differential conditioning trials in which an odor was paired with sucrose solution and another odor was presented without pairing with sucrose solution, sucrose-associated odor induced an increase in the level of salivation, but the odor presented alone did not. The conditioning effect lasted for one day after conditioning trials. This study demonstrates, for the first time, classical conditioning of salivation in species other than dogs and humans, thereby providing the first evidence of sophisticated neural control of autonomic function in insects. The results provide a useful model system for studying cellular basis of conditioning of salivation in the simpler nervous system of insects.PLoS ONE 02/2007; 2(6):e529. · 3.73 Impact Factor
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ABSTRACT: Reports on experience-dependent changes in invertebrate autonomic function are few. In the crab Chasmagnathus, repeated presentations of a visual danger stimulus (VDS) elicit long-term cardiac adjustments. Although these changes can be explained in terms of an associative process, they do not necessarily indicate an anticipatory conditioned response. In the present work, we investigated anticipation of the cardio-inhibitory response (CIR) after classical conditioning. We found that an initially seemingly neutral stimulus, which could trigger only a brief CIR as part of an arousal/orienting response, following pairing with the unconditioned stimulus, 24 h after a second exposure, triggered a significantly stronger CIR response compared to controls. We propose that, as a result of training, the conditioned stimulus acquires a different biological meaning, allowing the crab to anticipate the aversive stimulus.Physiology & Behavior 05/2010; 101(1):168-75. · 3.16 Impact Factor