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Biomedical subjects

Michel Cabanac

Publications and source records attributed to Michel Cabanac.

11 recordsLinked to original sources
PubMed2006

Adjustable set point: to honor Harold T. Hammel.

The value of a regulated variable in the absence of external perturbation stabilizes at the set point of the system. This set point is an information input that may be determined by an external signal to which the regulated variable is compared or may be determined by the structural characteristics of the system itself. In the case of temperature regulation the actual internal temperature is compared with the set point "wanted" by the organism. The activating signal for the regulatory responses, the "error signal," is the difference between the actual temperature and the set point. When an error signal is detected, the organism produces the available corrective responses. Yet, the notion of thermoregulatory set point has been challenged recently. Such a questioning entails that both fever and anapyrexia are useless concepts. This minireview examines the available arguments and data and concludes that to abandon the concepts of set point, fever, and anapyrexia is premature, at best.

Animals↗
PubMed2006

Sensory pleasure optimizes muscular work.

PURPOSE: To determine how an individual optimizes muscular work. SOURCE: Several previous investigations by the author that explored the hedonicity of various sensations aroused during work and compared the results with the subjects' performances. PRINCIPAL FINDINGS: When a subject is given the task to climb 300 m elevation on a treadmill, at various combinations of speed and slope, if slope is imposed and speed self adjusted, or speed imposed and slope self adjusted, the subject spontaneously climbs the 300 m in a constant time. Thus, the subject worked his body at a constant power (work x duration(-1)). Thus, a person optimizes his own behaviour spontaneously. Systematic exploration of the hedonic dimension (pleasure/displeasure) of sensory experience from various parts of the body, over a broad range of muscular work showed that pleasure is experienced when a useful stimulus, as judged from the point of view of optimization of physiological function, is present. Displeasure occurs when a noxious stimulus is present. When a stimulus is neither useful nor noxious, the sensation aroused is indifferent. The relationship of hedonicity with physiology is so tight that these properties of sensation can be used as a tool to explore the body's physiological integrity. Hedonicity is also aroused during muscular exercise. Experimental evidence will be provided to demonstrate that the pleasures/displeasures of sensory inputs from the chest and from muscles are the signals that are the source of optimal muscular work. CONCLUSION: The experimental results confirmed that pleasure is the common currency that is used by the brain to compare sensations aroused by muscular work from various parts of the body. Maximization of the algeabraic sum of these hedonic sensations optimizes the resulting muscular performance.

Exercise↗
PubMed2005

Diet induced weight loss accelerates onset of negative alliesthesia in obese women.

BACKGROUND: The physiological and behavioral responses to hypocaloric diet are to increase energy intake to defend a steady body weight. We utilized the method of "negative alliesthesia" for measuring the hedonic reponse to sweet stimulus before (Initial session) and 3 months after entering a weight loss program. The negative alliesthesia test is known by physiologists but few clinical data exist. It is based on the observation that repeated pleasant gustatory stimuli turn into unpleasantness in the process of alliesthesia. At first visit participants repeatedly ingested sweet stimuli until they found them unpleasant and rated quantitatively on a linear analogue scale their hedonic experience. This procedure was repeated every 3 min until participants felt displeasure to end the session. The same protocol was followed after three months of following a weight loss diet. Dieting energy intake was from 1400 - 2000 kcal/d for 8 wk. Energy composition was 50% carb:25% prot: 25% lipid. After 8 wk caloric intake increased by 50 kcal/wk, to reach daily intake of 1800 - 2400 kcal/d. Energy composition was 50% carb:22% prot: 27% lipid. We report results on the effect of slow weight loss on negative alliesthesia in ten obese female participants enrolled in a commercial diet program based on Canada's Food Guide (Mincavi). RESULTS: Results showed that diet lowered the mean BMI (Initial session 36.8 +/- 1.8 vs. 3 mo 34.9 +/- 1.8 kg/m2). At 3 mo the onset of negative alliesthesia, time to abandon experimental session, was shortened (Initial session 33 vs. 3 mo 24 min). The same trend was observed in the time to reach indifference (Initial session 21.9 +/- 3.8 vs. 3 mo 16.2 +/-2.4 min). There was no observed difference in maximum (Initial session +79.5 +/- 11.7; 3 mo +94.5 +/- 9.9 mm) and minimum (Initial session -90.0 +/- 14.4; 3 mo -106 +/- 11.1 mm) hedonic rating. CONCLUSION: Earlier onset of negative alliesthesia, as seen in our participants, is not consistent with previous hedonic studies that showed delayed or absent negative alliesthesia in participants when below their initial body weight. Therefore, it is hypothesized that the accelerated onset of negative alliesthesia observed in our obese participants after weight loss is suggestive of a lowered body weight set-point. Factors inherent to the weight loss diet studied here, such as mild energetic restriction, lowered palatability, and diet composition, may have played a role in this experimental outcome.

Adult↗
PubMed2005

Accelerated satiation after duodenal switch.

BACKGROUND: This is to introduce a new test "negative alliesthesia" for measuring satiation after bariatric surgery. It is a test that is well known by physiologists but has never been used clinically. It is based on the observation that repeated pleasant gustatory stimuli turn into unpleasantness in the process of satiation. METHODS: We measured the time it took for a repeatedly ingested sweet stimulus to become first unpleasant (negative alliesthesia) and then intolerable (satiety). At the same time, we measured the degree of pleasure aroused by the sweet stimulus (hedonic rating). The test was given to 9 patients before and 3 and 6 months after the duodenal switch procedure and in 10 morbidly obese patients, three times, 3 months apart. RESULTS: The test showed that negative alliesthesia and satiety were three times faster after surgery. The negative alliesthesia time decreased from 16.0 +/- 3.9 minutes to 5.7 +/- 1.4 minutes (P < 0.0004). The satiety time decreased from 26.7 +/- 5.0 minutes to 10.7 +/- 1.3 minutes (P <0.001). Finally, the hedonic rating for the sweet stimulus decreased from 78.8% +/- 15.7% to 49.9% +/- 13.0% at 3 months and 39.3% +/- 20.6% at 6 months after surgery, without, however, reaching statistical significance. CONCLUSION: The duodenal switch modified negative alliesthesia. It is too soon to say what place this test may have in bariatric surgery, but its simplicity and ingenuity are attractive.

Adult↗
PubMed2004

Flavor aversion learning induced by lithium chloride in reptiles but not in amphibians.

Flavor aversion learning occurs when digestive illness follows ingestion of a novel food. Such learning has been shown to exist in mammals and birds. In this experiment, we looked for flavor aversion learning in amphibians (Bufo paracnemis, Pachytriton breviceps) and reptiles (Basiliscus vitattus, B. basiliscus, Eumeces schneideri, Mabuya multifasciata). After intake of the novel food, the animals received i.p. injection of either lithium chloride (LiCl), an effective illness inducer, or a saline solution. A week later, the LiCl injection had not affected the food intake of the amphibians whereas in the lizards it had produced a strong aversion to the flavor of the novel food. These results are consistent with the hypothesis that specific mental capacities emerged with reptiles.

Amphibians↗
PubMed2003

Nicotine lowers the body-weight set-point in male rats.

Set-point of body weight was assessed by the behavioral method of the weight threshold to hoard food. Intra-peritoneal injection of nicotine (0.02-0.05 mg/kg) significantly lowered the rats' body weight set-point by 8.5+/-2.7 and 19.2+/-2.6 g (p< or =0.05). These results suggest that the administration of low-dose nicotine lowers the body-weight set-point and may be important in predicting the anticipated gain in weight frequently reported upon withdrawal.

Animals↗
PubMed2002

Pleasure in decision-making situations.

BACKGROUND: This study explores the role of pleasure in decision making. RESULTS: In Experiment 1, 12 subjects were presented with a questionnaire containing 46 items taken from the literature. Twenty-three items described a situation where a decision should be made and ended with a suggested solution. The other items served as filler items. The subjects were requested not to make a decision but to rate the pleasure or displeasure they experienced when reading the situation described in the item. The subjects' ratings were then compared to the decisions on the same situations made by the other subjects of the studies published by other workers. The ratings of pleasure/displeasure given by our subjects correlated significantly with the choices published by other authors. This result satisfies a necessary condition for pleasure to be the key of the decision making process in theoretical situations. In Experiment 2, a new group of 12 subjects rated their experience of pleasure/displeasure when reading various versions of 50 situations taken from daily life where an ethical decision had to be made (Questionnaire I) including 200 items. This was followed by a multiple-choice test with the 50 situations (Questionnaire II) using the same 200 items and offering the various behaviors. Subjects tended to choose ethical and unethical responses corresponding to their highest pleasure rating within each problem. In all cases the subjects' behavior was higher than chance level, and thus, followed the trend to maximize pleasure. In Experiment 3, 12 subjects reading 50 mathematical short problems followed by correct and incorrect versions of the answer to the problem (Questionnaire III), including 200 items. This was followed by a multiple-choice mathematical test with the 50 problems (Questionnaire IV) using the same 200 items and offering the correct and incorrect answers. In questionnaire IV, subjects tended to choose correct as well as incorrect responses corresponding to their highest hedonic rating within each problem. In all cases the subjects' behavior was higher than chance level, and thus, followed the trend to maximize pleasure. CONCLUSIONS: The results of the three experiments support the hypothesis according to which decisions are made in the hedonic dimension of conscious experience.

Adult↗
PubMed2002

Evidence that transient nicotine lowers the body weight set point.

OBJECTIVE: Smokers usually gain weight when they quit smoking. The present work explores the hypothesis according to which such a rise is a behavioral response to a raised body weight set point taking place when nicotine is eliminated from the body. RESEARCH METHODS AND PROCEDURES: The human body weight set point was assessed with classical behavioral and psychophysical methods, from the delay to experience negative alliesthesia when repeatedly ingesting sweet stimuli. Seven habitual smokers were tested once before lunch, after smoking (nonabstinent) as usual and once again after refraining from smoking (abstinent). Three additional nicotine-naive subjects were tested under the same procedure after receiving at 0730 h in the morning a transdermal nicotine patch (14 mg) or a placebo patch. Two of the subjects also received nicotine (7 mg) for a third session. RESULTS: Oral and transdermal administration of nicotine did not decrease the initial pleasure or modify the initial palatability of eating sweet stimuli, but significantly accelerated the following onset of self-reported displeasure (negative alliesthesia) aroused by repeated ingestion of sweet stimuli. DISCUSSION: These results are understood as an acute lowering of the body weight set point by nicotine. The body weight gain taking place after quitting smoking may, therefore, be explained by the removal of the lowering of the body weight set point induced by nicotine.

Administration, Cutaneous↗
PubMed2002

What is emotion?

There is no consensus in the literature on a definition of emotion. The term is taken for granted in itself and, most often, emotion is defined with reference to a list: anger, disgust, fear, joy, sadness, and surprise. This article expands on a thesis that motivational states can be compared to each other by means of a common currency (Philos. Trans. Roy. Soc. Lond. 270 (1975) 265-293). I have previously argued that this common currency is pleasure. Such a conclusion is based not on introspective intuition, as with early pre-scientific psychology (), but on experimental methods. As a follow-up to a definition of consciousness (Neurosci. Biobehav. Rev. 20 (1996) 33-40) as a four-dimensional experience (quality, intensity, hedonicity, and duration), I propose here that emotion is any mental experience with high intensity and high hedonic content (pleasure/displeasure).

Journal Article↗
PubMed2000

Beard vs. forehead, ten years later.

Ten years ago (1988), we observed in a sample of 100 men that the area of the glabrous skin above the eyebrows was proportional to the area of the hairy skin on the cheeks, lips, and chin. Ten to 11 years later, we measured again 39 of the former subjects to check longitudinally whether the relationship would still be valid. In the group of 39 subjects, the correlation was again significant and the regression was practically the same as that obtained in the same sample 10 years earlier. This would tend to show that ontogeny follows phylogeny. This results is understood as indirect evidence in favor of selective brain cooling in humans. Am. J. Hum. Biol. 12:460-464, 2000. Copyright 2000 Wiley-Liss, Inc.

Journal Article↗