Ingestive responses of human newborns to salty, sour, and bitter stimuli.

In 2 experiments a total of 204 16-90 hr old neonates were offered 2 fluids differing in taste for 3 min each. The volumes ingested were measured. Ss offered water and bitter and sour solutions did not ingest them differentially, which corroborated earlier observations with weaker solutions. A sucrose solution was used to raise baseline ingestion above that of water. Ss offered the sucrose solution with and without urea, citric acid, or sodium chloride consumed less of it when citric acid was added. They were indifferent to the addition of urea or sodium chloride. The failure to observe intakes lower than that of water suggests that newborns maximally inhibit their ingestion of water. The effect of sex, age, birth weight, and individual consistency on intake were assessed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some observations on the preference deficits produced by lateral preoptic lesions in the rat.

Conducted 4 experiments with a total of 20 female albino Sherman rats which show that, following water deprivation, Ss with lateral preoptic (LPO) damage lost the normal preference for glucose solutions. Food deprivation reinstated the preference. This dependency was specific to sweet-tasting fluids, and the deficit persisted even when thirst was alleviated prior to the preference test. Such Ss would drink sweet solutions in response to intravascular fluid depletion, but they were deficient in response to sweet solutions under nondeprived conditions. This last finding in particular suggests that hunger and palatibility, as determinants of the response to sweet solutions, may be dissociated by LPO damage. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of dietary NaCl deprivation during early development on behavioral and neurophysiological taste responses.

Investigated whether the gustatory system can be modified by restricting dietary NaCl during early development by recording neurophysiological taste responses in Sprague-Dawley rats at various times after deprivation (Exp I), and by measuring behavioral taste preferences in 3 groups of 7 NaCl deprived adult rats (Exp II). Overall findings indicate that Ss deprived of dietary NaCl from the 3rd day of gestation to 12 days postnatally and then placed on a NaCl-replete diet had chorda tympani nerve responses similar to those of nondeprived Ss when recordings were made at 28 days of age and older; however, preferences for NaCl solutions over water were significantly less than those of controls when tested at adulthood. NaCl deprivation in Ss from the 3rd day of gestation to approximately 35 days postnatally resulted in altered chorda tympani nerve responses to NaCl but not to other stimuli such as NH?Cl and KCl. Thus, it is concluded that restriction of dietary NaCl at a period in the rat's development when peripheral and central taste responses are changing results in short-term alterations in peripheral neural responses and in long-term changes in preference behaviors. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of lesions of the gustatory neocortex on taste aversion learning in the rat.

In 5 experiments, 110 normal male Long-Evans hooded rats and 125 Ss with lesions of the gustatory neocortex (GN) were compared for their ability to learn aversions to taste cues paired with toxicosis. When the taste presentation was followed immediately by toxicosis, normal Ss and 8 Ss with lesions of the posterior (visual) neocortex learned aversions to sucrose, sodium chloride, quinine hydrochloride, and hydrochloric acid solutions. Ss with GN lesions learned aversions to all solutions except sucrose. In preference tests, all solutions were shown to be discriminable from water by both normal and GN-lesioned Ss. Under conditions in which a 6-hr delay separated taste presentation and toxicosis, normals again learned specific aversions to all 4 solutions, but Ss with GN lesions failed to learn specific aversions to sucrose, sodium chloride, and hydrochloric acid solutions. It was shown that the ability of Ss with GN lesions to learn aversions to sucrose and quinine depended on stimulus concentration. It is proposed that the data can be accounted for by postulating a change in the threshold for taste illness associations following GN lesions. (30 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavior of sodium-deficient rats: The search for a salty taste.

Tested whether 188 Na-deficient rats would search for the taste of Na or the taste of salt. Ss were subjected to various conditions of food and water deprivation before being given a choice between solutions of varying saltiness. Na-deficient Ss displayed an appetite for solutions that humans judged as salty-tasting whether or not the solutions contained sodium salts. When offered a choice between a pair of sodium salts, Ss generally preferred the more salty-tasting solution. They tended to do the same for a pair of nonsodium salts and for a pair of sodium and nonsodium salts. Results show that human psychophysical judgments of saltiness are a good predictor of the choices that rats will make when Na-deficient. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Heredity and experience: Their relative importance in the development of taste preference in man.

Heritability estimates for sucrose, lactose, and sodium chloride taste preferences were uniformly low in a total of 311 pairs of monozygotic and like-sex dizygotic twins between 9 and 15 yrs of age. Black Ss preferred more concentrated solutions of all 3 tastants than did Caucasian Ss. This effect was independent of socioeconomic status in the total sample. Males preferred more concentrated solutions of sucrose and lactose than did females, but there were no sex differences in sodium chloride preference. The possibility that early intake experiences may play a role in the determination of enduring taste preferences in humans is discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effect of potassium depletion on mineral appetite in the rat.

Studied potassium appetite in normal female Sprague-Dawley rats and in rats in which the total body potassium had been reduced by 15-20%. Potassium depletion resulted in increased ingestion of solutions of NaCl, KCl, CaCl2, and quinine sulphate in concentrations that were unacceptable to normal Ss. The amount of potassium ingested was related to the degree of potassium depletion and repletion was usually completed within 24 hr. when potassium was offered. Potassium-depleted Ss also drank large quantities of aversive concentrations of sodium chloride. This was preferred to potassium chloride and its ingestion appeared to be unrelated to need. The appetite state was reversed by prior intragastric repletion with potassium but not with sodium salts. (19 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Escape from deficits in sodium intake after thalamic lesions as a function of preoperative experience.

Saline and water intakes in response to treatments with a natriuretic agent and a mineralocorticoid were studied in intact Sprague-Dawley male rats and in rats with lesions centered in the taste relay of the thalamus. Intact Ss responded to the treatments by increasing both saline and water intake. Ss with thalamic lesions that had never drunk saline prior to induction of the lesions generally did not increase their saline intake in response to the treatments but showed normal increases in water intake. In contrast, Ss with thalamic lesions that had drunk saline prior to induction of the lesions showed normal increases in both saline and water intake. Preoperative experience of sodium need did not protect Ss against the lesion-induced deficit. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of gastric loads and food deprivation on subsequent food intake in suckling rats.

In 4 experiments, a total of 478 suckling Charles River rats were subjected to deprivation periods of 6-8 hrs. Intake following deprivation was greater in deprived than in nondeprived Ss but did not increase with increasing deprivation. Gastric loads of NaCl solutions depressed subsequent intake; 3% NaCl was more effective than .9% NaCl. Other gastric loads of varying osmotic and caloric values also depressed subsequent intake. In order of increasing effectiveness in depressing intake, the gastric loads were protein hydrolystate, heavy cream, water, milk, lactose, glucose, and corn oil. Effectiveness was unrelated to osmotic or caloric value of the load. Gastric fill and, possibly, some property of carbohydrate appeared to be important determinants of satiety in the S. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sodium appetite in adrenalectomized rats following dietary sodium deprivation.

Experimented with operated, sham-operated, and comparison male Sprague-Dawley rats (N = 74). Adrenalectomized (Adrex) rats adjusted well during adrenal insufficiency when saline solutions were available. Despite continuous uncontrolled losses of relatively large amounts of sodium in their urine, they managed to maintain body fluids at approximately normal levels by replacing crucial sodium losses, if only temporarily, through frequent intakes of saline. It is concluded that the threshold for sodium appetite in Adrex rats is associated with relatively small sodium deficits, and roughly similar deficits also are effective in stimulating sodium appetite in intact Ss. When more pronounced losses result from maintenance on a sodium-free diet, Adrex Ss rapidly drink more than enough saline to replace their deficits. Thus, it seems evident that mineralocorticoids need not have a vital role in either the initial salt-drinking response of intact Ss to minor sodium deficits or their overcompensation for moderate sodium deficits. (32 ref.) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Chronic voluntary nicotine drinking enhances nicotine palatability in rats.

Examined the response of rats to nicotine (NI) solutions with the brief-exposure, taste reactivity (TR) test, and a 2-bottle, 24-hr preference test. Naive nondeprived Ss were administered intraoral infusions of distilled water and 1 μg/ml, 5 μg/ml, 10 μg/ml, 25 μg/ml, 50 μg/ml, and 100 μg/ml NI. NI solutions up to a concentration of 50 μg/ml elicited a number of ingestive TR responses similar to that by water. Ingestive responses significantly decreased and aversive TR responses significantly increased in response to 100 μg/ml nicotine. On the basis of these results, 2-bottle preferences for water vs 1 μg/ml, 5 μg/ml, and 0 μg/ml (water control group) NI were measured in 3 groups of naive Ss. Ss initially showed an equal preference for 0 μg/ml and 1 μg/ml NI. After 16 days of exposure, however, Ss developed a significant preference for 1 μg/ml NI. The preference ratio for 5 μg/ml NI significantly increased during the experiment, but the preference ratio remained significantly less than that for 1 μg/ml and 0 μg/ml NI solutions. Last, TR responses elicited by intraoral infusions of 1 μg/ml and 5 μg/ml NI were then measured in these Ss having had the 2-bottle experience. Ss showing a 2-bottle preference for the 1 μg/ml NI solution displayed significantly more ingestive TR responses to 1 μg/ml and 5 μg/ml NI than did the control Ss. Data indicate that prolonged voluntary access to NI results in an increased preference for NI and modifies the immediate oral/gustatory reactivity of the Ss to NI. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Food motivation and body weight levels in hypothalamic hyperphagic rats: A dual lipostat model of hunger and appetite.

Compared the food and water motivations of 26 normal and 29 hyperphagic female Carworth CFE rats using barpressing performance on continuous reinforcement, VI, and fixed-ratio schedules. Under conditions of food or water deprivation, hyperphagic Ss displayed normal barpressing rates for food or water when their body weights were limited to preoperative or control levels but subnormal barpressing rates when they were tested at obese body-weight levels. Under nondeprived conditions, dynamic hyperphagic Ss barpressed more than controls for a palatable milk diet, while obese hyperphagic Ss worked at control levels for this diet. The findings suggest a dual lipostat model of hunger and appetite to explain feeding and body weight regulations in normal and hypothalamic hyperphagic animals. (62 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Decreased testosterone levels and accelerated extinction of a conditioned taste aversion in fluid-deprived male rats.

The hypothesis that fluid deprivation accelerates extinction of a conditioned taste aversion in male Sprague-Dawley-derived rats by reducing serum testosterone levels was tested. Serum testosterone levels were found to be lower in fluid-deprived males than in nondeprived males (Exps 1 and 2). Exogenous testosterone treatment that results in high physiological levels of serum testosterone slowed the extinction of fluid-deprived gonadectomized males to rates comparable with those of nondeprived sham males (Exp 3). It was noted, however, that testosterone treatment was less effective in slowing extinction in fluid-deprived gonadectomized males than in nondeprived gonadectomized males even though the serum testosterone levels were the same (Exps 3 and 4). These results provide strong support for the original hypothesis, but they suggest that fluid deprivation also reduces sensitivity to testosterone. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bait shyness: Avoidance of the taste without escape from the illness in rats.

Conducted 3 experiments with 50 young adult Sprague-Dawley rats. Thirsty Ss habituated to drinking .12 M sodium chloride accepted .12 M lithium chloride for 5 min on the 1st trial but stopped short of their sodium baseline. With repeated trials they reduced consumption of the toxin by either (a) detecting subtle oral CS differences, thus avoiding toxicosis (UCS) or (b) detecting earlier signs of malaise (UCS), thus escaping further distress. When both solutions were masked with saccharin, discrimination was more difficult but still possible. When both solutions were mixed in a solution masking all 4 taste qualities, discrimination was severely disrupted. When oral sensors were bypassed with nasopharyngeal tubes, intragastric pumping Ss were unable to use postingestional cues to escape, even though such cues were proximal to the ultimate malaise. Oral cues at the distal end of the consummatory chain were extremely effective. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some hedonic consequences of the confirmation and disconfirmation of expectances.

In a test of the hypothesis that events which disconfirm expectancies will be perceived as unpleasant, Ss tasted a random sequence of sweet and bitter solutions. On the basis of certain signals given by the E, they developed expectancies or hypotheses about whether the next solution would be bitter or sweet. On trials when the Ss' expectancies were disconfirmed due to incorrect signals, the solutions were judged to taste more unpleasant. Thus, a bitter solution was rated more bitter; a sweet solution was rated less sweet. The results were interpreted in terms of Festinger's theory of cognitive dissonance. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Refined salt appetite methodology for rats demonstrated by assessing sex differences.

Describes a refined method for inducing and measuring salt appetite for studying behavioral and neurological functions. The efficiency and reliability of the procedures were demonstrated by parametric studies comparing the appetite behaviors of male and female rats. The method for inducing salt appetite coupled 2 days of dietary sodium deprivation with a brief diuretic treatment. The measurement procedure involved a 2-hr period of access to one of several NaCl solutions differing in palatability or concentration. The induction procedure allowed precise control of drive levels, and the measurement procedure yielded highly reliable results as a function of the properties of the incentives. 32 female mongrel rats consistently ingested about twice as much NaCl solution as did 32 male Ss, regardless of the palatability of the solution or of body sodium levels. At the same time, female Ss lost less sodium in urine following diuretic treatment. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Failure of sodium- and calcium-deficient rats to acquire conditioned taste aversions to the object of their specific hunger.

Attempted to condition taste aversions to the objects of 2 mineral-specific hungers in 2 experiments with a total of 116 male Sprague-Dawley rats. Both the innate preference of adrenalectomized Ss for sodium and the learned preference of parathyroidectomized Ss for calcium were studied. None of the sodium-deficient Ss poisoned after drinking NaCl reached a taste-avoidance criterion, even after 9 pairings of salt ingestion with aversive lithium chloride injections. 6 of 11 calcium-deficient Ss did not meet the salt-avoidance criterion after 10 pairings. Nondeficient control Ss learned to avoid these salt solutions completely after an average of only 3 such pairings. Besides unmasking a surprising degree of similarity between the learned and innate specific hungers studied, results clearly demonstrate a powerful influence of physiological need on aversion conditioning. (38 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The ontogeny of feeding in rats: I. Ingestive and behavioral responses to oral infusions.

Reports on 3 experiments with Charles River rat pups. When milk infusions were made through oral cannulas in the front of their mouths, 1–20 day old Ss actively ingested the diet, and their intake was related to the length of deprivation. Ss decreased their ingestive responding after they had consumed large volumes of milk. In addition, 1-, 3-, and 6-day-old Ss, when 24-hr deprived, exhibited an intense behavioral activation in response to milk infusion. The behavioral activation appeared to be stimulated primarily by taste and the opportunity to swallow. Milk infusions did not produce activation in older Ss; their behavior was more exclusively ingestive and food directed. Results demonstrate that (a) from birth, rat pups are capable of an active form of ingestion, independent of normal suckling from the mother; (b) such ingestion is controlled by physiological factors; (c) food has arousing properties in young animals; and (d) as pups grow older, their ingestive responding is refined from a generalized and nondirected activation to specific and directed feeding responses. (57 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Thalamocortical relations in taste aversion learning: II. Involvement of the medial ventrobasal thalamic complex in taste aversion learning.

Examined the involvement of the gustatory thalamic nuclei in fundamental taste reactivity, gastrointestinal reactivity, and conditioned taste aversion (CTA) learning. In Exp I, using 72 male Long-Evans rats, bilateral electrolytic lesions were produced in the medial ventrobasal thalamic complex (VBm), including the thalamic gustatory nuclei, in 1 group of Ss. For a 2nd group, at the conclusion of conditioning, lesions were produced in the anterior insular gustatory neocortex (AIGN). Results indicate that destruction of VBm thalamus attenuated taste reactivity to sucrose, citric acid, and quinine hydrochloride. Elimination of VBm thalamus markedly attenuated CTA learning. Results of neocortical lesion manipulations showed that the AIGN contributed to initial CTA learning in Ss lacking a mediodorsal-periventricular thalamus. Whether Ss lacking VBm thalamus used olfactory cues associated with drinking solutions to acquire CTAs was evaluated in Exp II, using 72 male Long-Evans rats. Results demonstrate that Ss lacking VBm thalamus and the olfactory bulbs could not acquire aversions to ingested LiCl following 8 conditioning trials. (54 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Orogastric determinants of drinking in rats: Interaction between absorptive and peripheral controls.

In 3 experiments with 24 female Sprague-Dawley rats, water intake of water-deprived Ss, drinking with absorption prevented by pyloric occlusion, was compared with that of Ss drinking normally. Drinking without absorption, under the control of only orogastric factors, was not graded in response to varied deprivation (Exp I). Orogastric controls effectively inhibited intake after absorbed water, but not isotonic saline, preloads (Exp II). The extent of orogastric inhibition was directly related to absorbed preload volume (Exp III). With large absorbed water preloads (9 ml), intakes with and without absorption were equal. Normal function of orogastric controls may thus be based on their interaction with absorption, which progressively enhances peripheral inhibition of drinking. (32 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)