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Biomedical subjects

R A Boakes

Publications and source records attributed to R A Boakes.

At least 19 recordsLinked to original sources
PubMed2006

Early handling reduces vulnerability of rats to activity-based anorexia.

Resistance to restricted feeding with and without wheel access was tested in rats handled (H) for 20 days since birth. Weight loss produced by 1.5-hr restricted food access was less in H than in non-handled (NH) males when tested aged 41 days. At this age combining food restriction with access to a running wheel (a procedure commonly known as activity-based anorexia, ABA) produced very rapid weight loss and no effect of handling was detected. When 75-day females were tested in the same way, under the ABA procedure H rats took longer than NH controls to reach the removal criterion. Simply restricting food access in these females produced variable weight loss, without detection of any handling effect. No differences in food intake or running were detected between H and NH rats in either males or females. In conclusion, handling seems to have a direct effect on rats' later response to either food deprivation alone or to an ABA procedure.

Animals↗
PubMed2002

Activity-based anorexia: ambient temperature has been a neglected factor.

Activity-based anorexia refers to the self-starvation of rats exposed to experimental conditions that combine restricted access to food with access to an activity wheel. This paper compares previous studies of this phenomenon in relation to the ambient temperatures (AT) that were employed. On this basis, and from some more direct evidence, we argue that AT is an important, but neglected, factor in activity-based anorexia research. More attention to AT is needed in future research, since its neglect threatens the validity of conclusions drawn from those studies. Furthermore, direct examination of the effect of AT on activity-based anorexia will allow a better understanding of the mechanisms underlying this phenomenon and the possible clinical implications for the treatment of human anorexia nervosa.

Animals↗
PubMed2001

The role of drinking in the suppression of food intake by recent activity.

The standard activity-based anorexia procedure provides rats with access to a running wheel while restricting their access to dry food. This can produce reduced food intake and progressive weight loss. Using this procedure, in the present study (Experiment 1) the authors found changes in drinking patterns both in the period of high activity preceding food access and during the feeding period. Varying the procedure by providing wet mash (Experiment 2) or by prior adaptation to a drinking schedule (Experiment 3) prevented the self-starvation effect. These results indicate the importance of drinking when analyzing the effect of recent activity on food intake.

Animals↗
PubMed2000

Resistance to extinction of conditioned odor perceptions: evaluative conditioning is not unique.

A tasteless odor will smell sweeter after being sampled by mouth with sucrose and will smell sourer after being sampled with citric acid. This tasty-smell effect was found in experiments that compared odor-taste and color-taste pairings. Using odors and colors with minimal taste (Experiment 1), the authors found that repeated experience of odor-taste mixtures produced conditioned changes in odor qualities that were unaffected by intermixed color-taste trials (Experiment 2). An extinction procedure, consisting of postconditioning presentations of the odor in water, had no detectable effect on the changed perception of an odor (Experiments 3 and 4). In contrast, this procedure altered judgments about the expected taste of colored solutions. Evaluative conditioning (conditioned changes in liking) is claimed to be resistant to extinction. However, these results suggest that resistance to extinction in odors is related to the way they are encoded rather than to their hedonic properties.

Adult↗
PubMed1999

Confusing tastes and smells: how odours can influence the perception of sweet and sour tastes.

This study investigated the relationship between perception of an odour when smelled and the taste of a solution to which the odour is added as a flavorant. In Experiment 1 (E1) sweetness, sourness, liking and intensity ratings were obtained for 20 odours. Taste ratings were then obtained for sucrose solutions to which the odours had been added as flavorants. Certain odours were found to enhance tasted sweetness while others suppressed it. The degree to which an odour smelled sweet was the best predictor of the taste ratings. These findings were extended in Experiment 2 (E2), which included a second tastant, citric acid, and employed four odours from E1. The most sweet smelling odour, caramel, was found to suppress the sourness of citric acid and, as in E1, to enhance the sweetness of sucrose. Again, odours with low sweetness suppressed the sweetness of tasted sucrose. The study demonstrated that the effects of odours on taste perception are not limited to sweetness enhancement and apply to sour as well as sweet tastes. The overall pattern of results is consistent with an explanation of the taste properties of odours in terms of prior flavour-taste associations.

Adult↗
PubMed1999

Sex differences in the relationship between activity and weight loss in the rat.

Access to a running wheel combined with restricted feeding produced body weight loss at an equivalent rate in male and female litter-mate rats (Experiment 1). Thus, despite weighing less and running more, females were not more vulnerable to this procedure. When factors influencing weight loss were varied, no sex difference was found in adaptation to a new feeding schedule or in the effect of single versus group housing (Experiment 2). The apparent critical difference was that body weight loss increased running in males but not in females (Experiment 3). In all rats, rapid recovery of body weight occurred when food access was no longer restricted (Experiment 1), suggesting that "activity-based anorexia" is a misnomer for weight loss by rats in a running wheel.

Animals↗
PubMed1997

Context dependency of conditioned aversions to water and sweet tastes.

Three experiments exposed rats (Rattus norvegicus) to a discriminative conditioning procedure whereby a specific fluid was followed by lithium in one environment but not in another. This produced context-specific aversion to water, as detected by 2-bottle tests in Experiment 1, and a context-dependent saccharin aversion, which was unaffected by context extinction, in Experiment 2. Experiment 3 found that sucrose preexposure increased contextual control over the aversion established by sucrose-lithium pairings but had no effect on the target context. By contrast, target context exposure during conditioning reduced aversion to this context but did not affect contextual control of the sucrose aversion. In conclusion, depending on the conditioning procedures, contextual control of a taste aversion can be independent of the context's Pavlovian properties.

Animals↗
PubMed1997

Weight loss in rats produced by running: effects of prior experience and individual housing.

To investigate factors affecting activity-based anorexia (ABA) or activity-stress (AS), rats were given 2-hr access to a running wheel immediately prior to their daily 1.5-hr food access during the light cycle. This produced a reduction in food intake, a steady increase in running, and a large drop in body weight with a prolonged delay before weight recovery began. Experiment 1 found that these effects were reduced in rats with prior experience of eating at this time of day. In contrast, prior experience of running in the wheel when on ad lib food enhanced these effects in Experiment 2, where a subsequent change for half the subjects to individual housing produced a further decrease in body weight. The latter factor was investigated from the outset of Experiment 3 and again individually housed rats showed greater weight loss than did group-housed rats. This experiment also found that in rats of the same age a low initial body weight predicts greater vulnerability to ABA. It was concluded that ABA results from activity-induced reduction of feeding, which prolongs adaptation to a new feeding schedule and is accentuated by social isolation.

Animals↗
PubMed1997

Activity-based anorexia in rats as failure to adapt to a feeding schedule.

Progressive weight loss resulting from restriction to a daily 1.5-hr feeding period and access to a running wheel, the Activity-Based Anorexia (ABA) effect, was obtained in 3 experiments. However, bodyweight recovered when adaptation to the feeding schedule preceded access to the wheel (Experiment 1), when feeding was at the start of the dark period (Experiments 2 and 3), and when wheel access was denied in the 4 hr before food (Experiment 4). It was concluded that ABA results from interference with adaptation to a new feeding schedule due to the development of anticipatory behavior.

Adaptation, Psychological↗
PubMed1993

Taste-potentiated odor aversion learning based on amphetamine.

This study sought to determine whether a taste can potentiate a conditioned odor aversion based on amphetamine as well as those based on lithium. A taste-potentiated odor aversion (TPOA) based on lithium was obtained in Experiment 1 only with a low concentration of an almond odor. This concentration was used in Experiment 2 where the taste, 0.1% saccharin, potentiated an odor aversion based on 1 mg/kg d-amphetamine. This was replicated in Experiment 3 where potentiation was found with doses of both 1 and 3 mg/kg amphetamine, and no effect of dose was detected. It was concluded that TPOA learning is not restricted to drugs such as lithium that produce conditioned unpalatability as well as conditioned aversions to a taste, because amphetamine does not produce conditioned unpalatability at the doses used here. Furthermore, because in Experiment 3 postconditioning extinction of the saccharin aversion removed the potentiation effect, it appears that this form of TPOA may depend on an association between the odor and taste, as proposed by within-compound theory.

Amphetamine↗
PubMed1993

Prevalence of anticipatory nausea and other side-effects in cancer patients receiving chemotherapy.

98 patients receiving chemotherapy for cancer were interviewed to determine the prevalence of anticipatory nausea and vomiting, anxiety and dietary changes. Among those who had received at least four treatments 41% reported at least mild anticipatory nausea (AN). For 24% this was a moderate to severe problem, which was significantly associated with a high level of anxiety about treatment. Prevalence at this level was independent of whether the subject was receiving treatment as an in- or an outpatient. Anticipatory vomiting (AV) was reported by only 12 patients, of whom 11 were women; this was the only effect of gender found in the sample. Independence between moderate AN and AV was also suggested by a difference in type of event triggering the effect: predominantly odours for AN and thoughts of the treatment for AV. Changes in diet after commencing chemotherapy were reported by 50% of patients who had received at least four treatments. These most commonly took the form of aversions to meat and then to coffee, and were attributed most frequently to changes in taste and then to loss of appetite.

Adolescent↗
PubMed1992

Potentiation by a taste of toxicosis-based context conditioning: effects of varying the test fluid.

Rats that drank water in a distinctive environment and were then injected with lithium chloride (water-lithium condition) were compared with those given an added taste on those conditioning sessions (sucrose-lithium condition). In three experiments this taste potentiated a conditioned aversion to the context, as measured by suppression of intake of another solution: either a novel sour taste (Experiments 1 and 2) or a familiar saline solution (Experiment 3). In contrast, this potentiation effect was not detected when subjects were tested with water, whether a high or low dose of lithium was used (Experiment 2). Instead, in Experiments 1 and 2 water-lithium subjects drank less water than did the sucrose-lithium subjects on such tests i.e. an apparent overshadowing effect, which was the opposite outcome to that found previously using almost identical procedures. Intake on recovery sessions in another context suggested that, when water is used as the test fluid, potentiation can be masked by two factors: a context-dependent aversion to water in water-lithium subjects, and a conditioned inhibition effect of water in sucrose-lithium subjects. These may account for previous failures to detect potentiation of context conditioning.

Animals↗
PubMed1987

Early experience and reinforcer quality in delayed flavour-food learning in the rat.

The ability of hungry rats to associate flavours with the consequences of ingesting glucose solutions was studied in three experiments. Experiment 1 used a procedure in which on some days one flavour, e.g. cinnamon, was presented and followed after 20 min by 20% glucose, while on other days a second flavour, e.g. wintergreen, was presented, but not followed by any event. During this training, subjects who received quinine-tainted glucose increased their consumption of the predictive flavour relative to groups given no quinine, but quinine tainting did not affect conditioned preference for the predictive flavour in choice tests. With the aim of discovering whether prior experience of a variety of foods improves ability to learn new flavour-calorie associations, Experiment 2 and used a similar procedure to compare subjects raised on a varied diet ("supermarket" rats) with controls previously given only chow. Contrary to expectation, the supermarket rats showed some impairment both on this delay task and, in Experiment 3, on one using a "mixtures" procedure. This involved presenting a mixture of one cue flavour with glucose-quinine on some days and a mixture of a second cue with an equally palatable saccharin solution on other days. Acquisition was particularly rapid in control subjects, reaching asymptote after only two flavour-glucose pairings. It was concluded that neither a decrease in palatability, as in Experiment 1, nor prior experience with a range of foods, as in Experiments 2 and 3, improve a rat's ability to associate a new flavour with calories.

Analysis of Variance↗
PubMed1986

Can rats learn to associate a flavour with the delayed delivery of food?

Associations between a specific flavour and access to food were studied using a discrimination procedure devised by Holman (1975). This involved giving rats one flavour (e.g. cinnamon) of saccharin solution on some days, and following this by delivery of food, and a second flavour (e.g. wintergreen) on other days which was never followed by food. Experiment 1 used glucose delivered after a 30-min delay and a slight increase in preference for the paired flavour was detected. Using a 20-min delay Experiment 2 varied the kind of food used; some evidence for discrimination learning was again found in the glucose group, but there was no evidence that rats could associate a flavour with starch solution or solid chow over this delay. To check that the general procedure was a sensitive one, in Experiment 3 one flavour was added to glucose i.e. without delay, and this produced large shifts in a subsequent preference test. Overall the results threw doubt on claims that rats as readily form flavour-calorie associations over delays as they do flavour-toxicosis associations.

Animals↗
PubMed1986

Effects of basolateral amygdala lesions on taste aversions produced by lactose and lithium chloride in the rat.

In Experiment 1, intact rats were given either lactose or sucrose solutions. Although on first exposure they readily consumed lactose, its ingestion produced a conditioned taste avoidance which was partly extinguished by repeated sucrose exposure after lactose conditioning. In Experiment 2, rats with large bilateral electrolytic lesions of the basolateral amygdala and those with either sham or no operations were given two pairings of saline with LiCl injections (upper gastrointestinal tract discomfort) and in a separate condition access to high levels of lactose (lower gastrointestinal tract discomfort). Conditioned taste avoidances were measured both by two-bottle tests and by video recordings of the rats' orofacial and somatic responses. The lesions attenuated LiCl-induced taste aversion but not lactose-induced taste avoidance, results demonstrating that taste avoidance can occur without the basolateral amygdala. The results suggested that aversions based on distaste can be distinguished from avoidances based on danger, not only in terms of orofacial responses but also in terms of their neuroanatomical substrate.

Amygdala↗
PubMed1978

A study of misbehavior: token reinforcement in the rat.

The purpose of this research was to investigate the phenomenon of misbehavior described by Breland and Breland (1961). Rats were trained to obtain ball-bearings and drop them in a hole for food or water reinforcers. In confirmation of the Brelands' observation, many subjects were slow to deliver the balls, and frequently attempted to chew them before they were dropped. A series of four experiments, in which the same rats were used throughout, showed that delivery times tended to be longer with food than with water, and that these times increased when nylon balls were substituted. The effect of motivational level was investigated by varying both deprivation and amount of prefeeding; no effect on delivery time was detected, although other measures of performance were affected by motivational factors. Similar results were obtained in a final experiment that employed a new set of naive subjects. The studies demonstrated that misbehavior can be studied in an experimental situation, and the results supported an analysis in terms of competition between stimulus-reinforcer and response-reinforcer contingencies. The question of why such effects have not been reported in previous token reinforcer studies was unanswered.

Journal Article↗