The effects of septal and olfactory bulb lesions on stimulus reactivity.
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As fear conditioning paradigms have failed to find state-dependent retention (SDR) in rats dissociated by the estrous state, an attempt was made to establish a paradigm involving the attenuation of flavor neophobia as a more sensitive indicator of SDR. Experiment 1 established that the paradigm did indicate SDR in male rats dissociated by pentobarbital (10 mg/kg). Experiment 2 generalized the utility of the technique by employing an endogenous state, shock-induced stress, as the dissociative state. Having proved to be an indicator of SDR in the first two experiments, the technique was used in Experiment 3 to investigate the possible dissociative characteristics of the estrous state in female rats. Estrus was investigated because, due to the hormonal condition during estrus, it may provide a useful tool in investigating the dissociative aspects of human perimenstrual periodic psychosis. In Experiment 3, using ovariectomized female rats brought into estrus by injection of estrogen and progesterone in a sequence and amount comparable to the natural cycle, estrus was not demonstrated to be dissociative, i.e., did not produce SDR. The implications of these results in relation to perimenstrual periodic psychosis were discussed.
This study tested a number of hypotheses concerning the interrelationships between the olfactory abilities and the volume of nasal airflow in laryngectomees. Data were collected from 25 laryngectomees and 25 control subjects and comprised the following: 1) Odor threshold and identification test results. In the threshold test, an 11-step aqueous dilution series of butanol was used. In the odor identification tests, 14 common odorants were used. 2) Measurement of nasal air flow volume in liters per minute. For olfaction and airflow, the laryngectomees' measurements were made under two conditions: 1) using unassisted airflow through the nose, and 2) using a laryngeal bypass that linked the stoma to the mouth and allowed airflow through the nose. The major findings showed that among laryngectomees olfactory abilities depend on nasal airflow. It is concluded that laryngectomees have intact olfactory mechanisms that function normally when adequate airflow volume is provided.
BACKGROUND & AIMS: The elderly are at an increased risk of poor nutritional status which is mutually interacting with functional status. We evaluated the effects of a liquid nutrition supplement on anthropometric and functional indices in elderly people. METHODS: Subjects (n=68; mean age=82+/-7 years) with body mass index <or=25 kg/m(2) received either a supplement or a placebo for 6 months. Anthropometric (body weight, bioelectrical impedance, calf circumference), biochemical (albumin, prealbumin), functional parameters (handgrip strength, timed 'up and go' test) and dietary intake were measured. Activities of daily living and Nottingham Health Profile (NHP) were assessed. RESULTS: No compensation of energy intake occurred. After 6 months, the supplement group had gained more weight (+1.6 kg) than the placebo group (+0.3 kg) (P=0.03). No other significant changes in anthropometric, functional or blood parameters were seen. There was a significant improvement on the section 'sleep' of the NHP (mean change+/-SE=-0.38+/-0.19 for supplement vs 0.24+/-0.19 for placebo, P=0.03). CONCLUSION: Dietary supplementation led to an increase in body weight and had a positive influence on sleep in elderly persons. Supplementation did not affect energy intake from regular meals and thus resulted in additional energy intake.
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Fungiform papillae of the tongue vary in their appearance. It is not rare for them to be pigmented in black subjects, but this is less common in Asians. We report a case of pigmented fungiform papillae in a 65-year-old Vietnamese man. The patient also had recurrent aphthous ulceration and hepatitis C. Pigmentation affected all fungiform papillae and was asymptomatic. Macrocytosis was noted on full blood examination, while liver function tests were normal. The pigmentation of the fungiform papillae remained stable.
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Olfactory and gustatory disorders are by no means uncommon, and may be associated with an appreciable impairment of the patient's quality of life. In many cases, diagnosis and treatment is not easy, and necessitates interdisciplinary cooperation between the general practitioner, internist, ENT specialist, neurologist and psychiatrist. Many of the non-evidence-based treatments still applied in hospitals and the physician's office should, for reasons of quality control and to avoid polypragmasy possibly associated with undesirable side effects, be employed with reservations. With reference to the guidelines issued by the working group Olfactologie/Gustologie der Deutschen Gesellschaft für HNO-Heilkunde, Kopf- und Hals-Chirurgie (Olfactology/Gustology of the German Society of ENT Medicine, Head and Neck Surgery), a review of the causes, diagnosis and treatment of olfactory and gustatory disorders [3,4] is presented.
Seven patients with congenital anosmia underwent detailed chemosensory evaluation, followed by the performance of biopsies of the olfactory region. Olfactory epithelium was not found in any of the biopsy specimens. It appears therefore that patients with congenital anosmia lack any olfactory epithelium. Several possible explanations for this finding are discussed. The most attractive hypothesis is that the olfactory placode forms either normally or abnormally during development but later degenerates and is replaced with respiratory epithelium. Only one patient in our series had congenital anosmia in association with a syndrome (Kallmann's syndrome), indicating that congenital anosmia is found more often as an isolated symptom.
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Complementary neurophysiological recordings in macaques and functional neuroimaging in humans show that the primary taste cortex in the rostral insula and adjoining frontal operculum provides separate and combined representations of the taste, temperature and texture (including viscosity and fat texture) of food in the mouth independently of hunger and thus of reward value and pleasantness. One synapse on, in the orbitofrontal cortex, these sensory inputs are for some neurons combined by learning with olfactory and visual inputs. Different neurons respond to different combinations, providing a rich representation of the sensory properties of food. In the orbitofrontal cortex, feeding to satiety with one food decreases the responses of these neurons to that food, but not to other foods, showing that sensory-specific satiety is computed in the primate (including human) orbitofrontal cortex. Consistently, activation of parts of the human orbitofrontal cortex correlates with subjective ratings of the pleasantness of the taste and smell of food. Cognitive factors, such as a word label presented with an odour, influence the pleasantness of the odour and the activation produced by the odour in the orbitofrontal cortex. These findings provide a basis for understanding how what is in the mouth is represented by independent information channels in the brain; how the information from these channels is combined; and how and where the reward and subjective affective value of food is represented and is influenced by satiety signals. Activation of these representations in the orbitofrontal cortex may provide the goal for eating, and understanding them helps to provide a basis for understanding appetite and its disorders.
Cognition in transgenic mouse models of Alzheimer's disease (AD) has been predominantly characterized in explicit spatial orientation tasks. However, dementia in AD encompasses also implicit memory systems. In the present study a line of transgenic mice (TgCRND8) encoding a double mutated allele of the human amyloid precursor protein (APP) genes was evaluated in an implicit associative learning task of conditioned taste aversion (CTA). CTA is a form of Pavlovian classical conditioning, in which a mouse learns to avoid a novel taste of saccharine (conditioned stimulus) paired with an experimentally induced (systemic injection of lithium chloride) nausea (unconditioned stimulus). In contrast to conditioned non-Tg mice, TgCRND8 APP mice developed weaker aversion against saccharine and quickly increased its consumption in repeated tests. These results indicate that TgCRND8 mice show a significant impairment not only in explicit spatial memory, as has been previously shown [Nature 408 (2000) 979], but also in implicit memory. Control experiments confirmed that TgCRND8 and non-Tg mice had comparable taste sensitivities in response to appetitive as well as aversive tastes. The study suggests that the CTA paradigm can be a sensitive tool to evaluate deficits in implicit associative learning in APP transgenic mouse models of AD.
The phenylthiocarbamide (PTC) taste test was investigated for its potential as a genetically based biological marker for depression. One hundred and one male and female adults (including 6 patients hospitalized for depression), aged 18-36, completed a multifactor depression questionnaire that included the Beck Depression Inventory (BDI), a scale that measures severity of depression in mother and father, and a commercially prepared PTC (paper) taste test. As predicted, PTC tasters reported significantly higher levels of depression on the BDI than nontasters (p less than .05); also, they scored higher on 5 of the 21 items (p less than .05). Significantly more subjects who reported a mother debilitated by depression were PTC tasters (p less than .05). Limitations and implications of these findings are discussed.
Several studies have examined the gender differences in the area of emotion, but few data are available in the field of gustation. Yet, such differences are observed in clinical manifestations of nutritional disorders, such as a greater incidence of carbohydrate cravings in women. The aim of this study was consequently to examine the influence of gender on emotional responses to taste, by comparing autonomic responses and basic emotions associated with primary tastes between men and women. Thirty-four subjects (17 males, 17 females, mean age=28) participated in the experiment. Taste stimuli were solutions of 0.3 M sucrose (sweet), 0.15 M NaCl (salty), 0.02 M citric acid (sour) and 0.00015 M quinine sulfate (bitter). Evian mineral water served as the diluent and control (neutral taste). Five autonomic parameters [skin potential (SP) and resistance (SR), skin blood flow (SBF) and temperature (ST), instantaneous heart rate (IHR)] were simultaneously and continuously recorded when subjects tasted the five solutions. The patterns of autonomic responses, obtained for each primary taste and each subject, were transcribed into one of the six basic emotions defined by Ekman (happiness, surprise, sadness, fear, anger and disgust), according to a previously described method for odorants. Results evidenced that the mean variations of each autonomic parameter did not significantly differ between men and women, even if skin resistance and cardiac responses were stronger in men than in women. Concerning the basic emotions associated with each primary taste, a similar distribution for men and women was obtained for sweet, bitter and control solutions, whereas more differences were observed for salt (P=.02) and sour solutions.
The results in this article show that although electrolytic amygdala lesions disrupt learning of a conditioned taste aversion (CTA), ibotenic acid-induced, axon-sparing lesions of the amygdala do not. However, ibotenic acid lesions of the insular cortex do disrupt learning of a CTA. Electrolytic, but not ibotenic acid lesions of the amygdala, interrupt axons running between the insular (gustatory) cortex and the brain stem/hypothalamus. It is the destruction of these projections which appear to underly CTA deficits after amygdala lesions. Other results revealed that ibotenic acid lesions of the insular cortex attenuated the reaction to the novel taste of saccharin in a familiar environment but failed to affect the ingestion of a novel food in a novel environment or passive avoidance learning. Conversely, ibotenic acid lesions of the amygdala did not affect the reaction to novel saccharin in a familiar environment but did impair both the reaction to novel food in a novel environment and passive avoidance learning. We conclude that the insular cortex is involved in reactions to the novelty and associative salience exclusively of taste stimuli, whereas the amygdala is probably more concerned with the reaction to more general aspects of novelty in the environment and in fear-motivated behavior.
In some isolated parts of North Africa, there persists an ancient Berber custom of imposing an overfeeding regimen on young girls before marriage, to achieve an obesity which is regarded as aesthetically pleasing. We have studied the effect of such a regimen, lasting 12--16 weeks, on blood lipids and on the affective reactions to sweet tastes in nine subjects. It is known that the pleasantness of alimentary cues i.e., the feeding behaviour, depends on the subject's nutritional state. Only three subjects gained weight (by 3,5 and 8 kg), in spite of the strong pressure to overeat. No change in plasma lipid concentrations were observed. Nevertheless, at the end of the regimen every subject showed a highly significant decrease in the rated pleasantness of sweet stimuli when they were tested fasting. However, the reduction in sweet pleasantness induced by ingestion of a 200 ml load of 1.4 M glucose solution was not changed by the overfeeding. Thus, pressure to overfeed can reduce hunger, as seen in the attractiveness of sweet foods in fasted subjects, without modifying glucose-induced satiety.