Alter Food Preference Research Articles

Oropharyngeal Dysphagia in the Elderly

Considerable evidence exists to suggest that normal aging alone does not cause significant impairment to the ability to swallow. Although there are changes in muscular tension, speed of responses, taste sensitivity, and smell, the physiology of swallowing remains relatively intact. There is evidence suggesting that the duration of the oropharyngeal swallow is longer in older females and that esophageal motility slows in normal aging. Elderly persons do produce multiple lingual gestures and may eat softer and less spicy foods. These changes are subtle and subclinical but do not indicate oropharyngeal dysphagia. Oropharyngeal dysphagia in the elderly is the specific result of a pathologic condition or illness that may occur more commonly in elderly persons. These conditions are neurologic, neuromuscular, systemic, immunologic, psychiatric, environmental, or societal in nature. Oropharyngeal dysphagia is commonly found in institutionalized elderly populations and presents an ethical dilemma in treatment.

Role of noradrenaline and serotonin in the basolateral region of the amygdala in food preferences and learned taste aversions in the rat

First, it was confirmed that bilateral lesions in the basolateral region of the amygdala (ABL) of the rat increased the time spent eating novel as compared to familiar food in a food preference test, and that the lesions impaired learned taste aversion to a sucrose solution which had been paired with lithium chloride. Then the roles of noradrenaline and serotonin in the amygdala in these aspects of food intake were investigated. In Experiment 2, it was shown that injections of 10 and 20 nmoles of noradrenaline (NA) into the ABL increased the time spent eating familiar food in the food preference test. Higher doses of NA (50 and 100 nmoles) increased the total time spent eating without changing the preference of the rats for familiar or novel food, and produced behavioral side effects. Serotonin (5HT) injected into the ABL in doses of 10, 50 and 100 nmoles did not modify the pattern of choice of the foods. In Experiment 3, it was shown that depletion of NA in the ABL with 10 μg 6-hydroxydopamine did not alter the level of feeding of novel and familiar foods, but did impair taste aversion Depletion of 5HT in the ABL with 10 μg 5,7 dihydroxytryptamine did not alter food preferences or impair the taste aversion learning. The depletions of NA and 5HT were confirmed biochemically. These results provide further evidence for a role of the amygdala in preferences for novel as compared to familiar foods and in learning that the ingestion of a food is associated with sickness, and suggest that noradrenaline but not serotonin in the amygdala is involved in these types of control of food intake.

Calculation of percentage changes in volumes of blood, plasma, and red cells in dehydration.

Calculation of percentage changes in volumes of blood, plasma, and red cells in dehydration.

Altered food preferences after lesions in the basolateral region of the amygdala in the rat.

Rats with lesions in the basolateral amygdala chose different foods from control rats in 10-min. food-preference tests. The normal rats ate primarily familiar chow, while the amygdala-lesioned rats ate primarily novel foods. The lesioned rats did not select indiscriminately but showed definite preferences. With repeated testing, the normal rats' preferences became similar to those of the amygdala-lesioned rats. Food-preference tests in a disturbing environment suggested that the difference between the lesioned and control groups was not due to a general alteration in behavior such as fear. Other aspects of ingestive behavior, such as body weight regulation, were not primarily altered by the lesions. The basolateral amygdala may therefore be concerned with the selection of foods on the basis of previous experience. Amygdaloid neurons are activated in eating and drinking elicited by electrical stimulation of the lateral hypothalamus in rats (E. T. Rolls, 1972). This indication that amygdaloid neurons are involved in eating and drinking is strengthened by the finding that the amygdaloid neurons directly excited by the stimulation have the same absolute refractory period as the neurons through which the eating and drinking are elicited (E. T. Rolls, 1973). To investigate further the role of the amygdala in eating, ingestive behavior following amygdaloid lesions was analyzed, as described here. The lesion electrodes were aimed at the basolateral region of the amygdala, which is the area in which neurons were activated in the electrically elicited eating and drinking (E. T. Rolls, 1972). Electrophysiological and behavioral studies (see E. T. Rolls, 1972) support the hypothesis that the amygdala is involved in reinforcement. This hypothesis was utilized in the experiments described here. A choice of foods was given to the lesioned animals to determine whether the reward value of different foods measured by food preference is altered by the lesions.