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At least 1,153 records · Page 64Linked to original sources
PubMed1996

Olfactory control of mosquito behaviour.

The following papers will tell us much about our current knowledge of certain aspects of the olfactory control of mosquito behaviour-specifically host-locating behaviour. More importantly, as we read the papers, we should pay attention to the insights they will provide about what is not known and to the questions that our lack of knowledge should raise. The authors will also provide us with some new approaches and methodologies that we can apply to the study of mosquito physiology and behaviour.

Animals↗
PubMed1996

Olfactory basis of host location by mosquitoes and other haematophagous Diptera.

The behavioural role of odours released by mosquito hosts is poorly understood, indeed for many species it is still uncertain whether olfactory cues play a significant part in host location. Generalist attractants, such as CO2, have found application in mosquito trapping systems, and yet more host-specific attractants, such as L-lactic acid, remain of questionable value. Recent work with other haematophagous Diptera, notably Glossina, has shown that by a co-ordinated multidisciplinary approach it is possible to develop odour-baited trapping systems with a high level of attractiveness and specificity. Many of the compounds shown to attract Glossina have been tested with mosquitoes, and one of these, 1-octen-3-ol, attracts female mosquitoes of a number of species, but only in the presence of CO2. The behavioural significance of other compounds identified as host attractants of haematophagous Diptera, such as phenols, indoles and carboxylic acids, are currently under investigation. Efforts to produce a host odour attractant for the highly anthropophilic species Anopheles gambiae have been hindered by the chemical nature of the compounds associated with its human host, although a number of short-chain fatty acids identified in sweat samples have been shown to be electrophysiologically active.

Animals↗
PubMed2007

Diademed sifakas (Propithecus diadema) use olfaction to forage for the inflorescences of subterranean parasitic plants (Balanophoraceae: Langsdorffia sp., and Cytinaceae: Cytinus sp.).

Primates usually locate food resources using visual cues and memory, yet the potential for olfactory-guided (or olfactory-assisted) food location remains relatively unexplored. Here we report observations of wild Propithecus diadema that strongly suggest that olfaction is used to locate the inflorescences of two subterranean parasitic plant species (Langsdorffia sp. and Cytinus sp.). These valued but seasonal food resources are found obscured in leaf litter, and sifakas spend considerable time on the ground engaged in what appears to be olfactory exploration before they locate the inflorescences. Because they are visually obscured and occur within a substrate that is rarely used by sifakas, accidental discovery of these resources seems unlikely. Individuals may learn to exploit them by watching conspecifics.

Animals↗
PubMed1984

Puncture marks on early African anthropoids.

Field studies of living primates have shown that primate predation is a rare event. This must also have been true for past primate communities. In the Fayum Oligocene of Egypt, specimens of all four species of Upper Fossil Wood Zone primates show evidence of tooth puncture marks. Of the four potential groups of primate predators--the snakes, the raptors, the crocodiles, and the primitive carnivores or creodonts--only the crocodiles and the creodonts could have made these puncture marks. When one compares the feeding habits of living crocodiles and mammalian carnivores with the evidence from the Fayum, it appears that the Fayum primates were preyed upon and/or scavenged by mammalian carnivore-like animals. The dismemberment of the Fayum primates by Oligocene predators indicates, in part, why the Fayum fossil material is rarely articulated. Bone damage by predators may well set limits on what bone associations can be discovered in the Fayum even before the bones are scattered and buried by depositional processes.

Alligators and Crocodiles↗
PubMed1990

The nature of living systems.

Living systems theory (LST) is concerned with eight levels of living systems, each of which is composed of 20 critical subsystems that carry out essential life processes. As a result of a continuous biosocial evolution involving progressive fray-out of components, the more recently developed levels in this hierarchy have become very complex. A brief summary of LST is presented in this article. Following this is a detailed analysis of current knowledge about the timer, which we have recently included in our list of subsystems.

Animals↗
PubMed2003

Classical conditioning in the rat fetus. III. Retention, extinction, and re-activation of the conditioned response (CR).

A single paired presentation of an artificial nipple (conditioned stimulus, CS) and milk (unconditioned stimulus, US) resulted in classical conditioning. When re-exposed to the artificial nipple CS after conditioning, fetuses showed fewer oral grasp responses compared to control fetuses exposed to the milk (US) and artificial nipple (CS) in an unpaired fashion. The reduction in oral grasping was evident when the test of oral grasping was administered 18 min after conditioning but not 21 to 30 min after conditioning (Experiments 1a and 1b). Experiments 2a and 2b confirmed that nine or more exposures to the CS after conditioning, without a milk infusion, resulted in experimental extinction of the conditioned reduction in oral grasping. One re-exposure to milk during the period after classical conditioning was sufficient to re-activate memory for the association between artificial nipple CS and milk US (Experiment 3a). Fetuses exposed to one or two re-activation treatments that comprised an intraoral infusion of milk showed evidence of the conditioned reduction in oral grasping when tested after a delay sufficient to produce forgetting. Experiment 3b showed that the orosensory properties of milk were sufficient to re-activate fetal memory for the association between artificial nipple and milk. Experiment 3c indicated that central injection of 10 ng of dynorphin A 1-13 re-activated fetal memory for the classically conditioned association. Experiments 3b and 3c suggested that the orosensory properties of milk activated a kappa opioid system in the fetal brain that reduced oral grasping of the artificial nipple during the test for oral grasping.

Animals↗
PubMed2001

The effect of early specific feeding on food conditioning in cats.

Four cats were fed with beef only (beef cats) and 4 cats were fed with tuna only (tuna cats) during the first 6 months of their lives. Thus, they were deprived of a variety of food tastes. The cats then were trained in instrumental conditioning. After criterion performance was achieved, they were retrained with alternated food: In the beef cats, tuna was used, and in tuna cats, beef was used. There were six stages with alternated food. The beef cats acquired a pushing response markedly slower than the tuna cats because they often refused to eat the beef reward. Moreover, both the beef and the tuna cats preferred tuna in stages with alternated food. In contrast, there was no difference in attractiveness between beef or tuna in another 4 cats nondeprived of a variety of food tastes. Hence, early deprivation of a variety of food tastes may reveal an inborn food preference.

Aging↗
PubMed1982

Appetitive conditioning in neonatal rats: conditioned orientation to a novel odor.

These experiments document a form of early appetitive learning in rats obtained using classical conditioning procedures. Some of the special determinants of this conditioning are described, as well as ontogenetic changes in the effectiveness of training procedures. Learning was apparent when deprived 3- and 6-day old rats oriented to and maintained contact with a novel and normally aversive odor after this odor had been paired with oral infusions of milk (Experiment I). The effectiveness of the conditioning procedures depended on the temperature at which pups were trained (Experiment IB). Moreover, the reinforcing properties of milk infusions depended on deprivation (Experiment IC). This conditioned change in responsiveness to odor was specific to the odor that had been paired with milk (Experiment II) and was retained for at least 24 hr (Experiment III).

Age Factors↗
PubMed1984

Appetitive conditioning in neonatal rats: conditioned ingestive responding to stimuli paired with oral infusions of milk.

Components of rat pups' ingestive responses to orally infused milk came to be elicited by a novel odor conditioned stimulus (cedar) that had been repeatedly paired with milk infusions (Experiment I). Pups responded specifically to one odor, and they did not generalize their conditioned responding to either another odor or an unscented airstream (Experiment II). Ingestive responses could also be conditioned to a vibrotactile CS paired with milk, although levels of conditioned responding were lower than were obtained with an odor CS (Experiment III). Pups' internal state determined the effectiveness of training, in that pups that were removed from their dam for 24 hr showed reliable conditioned responding, while nondeprived pups and dehydrated pups did not (Experiment IV). Finally, pups showed retention of conditioned responding for at least several days after training (Experiment V).

Animals↗
PubMed1988

Sibling inhibition of hoarding in postweaning hamster pups (Mesocricetus auratus).

If hamster pups are placed in individual cages at weaning (21 days of age) they begin to hoard food immediately; within 2-6 days, they hoard 90% of the food they take from their food dish in the course of a 1-hr test, consuming only 10% of it. Pups that remain with their littermates after weaning in large group cages do not hoard food until they are placed in individual cages, when hoarding starts immediately. The inhibitory effect of littermates is just as pronounced in hamsters that have been allowed to hoard food in individual cages for 14 days after weaning and are then regrouped into litters. If litters are housed in divided cages that prevent physical interactions among littermates, but allow the interchange of olfactory, auditory, and some visual cues, hoarding is suppressed to an intermediate level. These results show that the presence of siblings inhibits the expression of hoarding, partly as a result of direct physical interactions and partly through the agency of sensory cues. The onset of hoarding following the dispersal of young from the nest cannot be explained as a motivational consequence of the young no longer having access to the mother's food hoard.

Aging↗
PubMed1989

Dopamine D-2 receptor mediation of response suppression learning of young rats.

In three experiments, the effects of augmenting or blocking dopamine (DA) D-2 receptor activity on the ontogeny of response suppression learning of preweanling rat pups were determined. In the initial experiment, rat pups were trained to traverse a straight alley for nipple attachment to an anesthetized dam. When footshock (0.2 mA, 0.5 sec) was made contingent on responding, younger (11- and 13-day-olds) rat pups were deficient to older (17- and 19-day-olds) pups at withholding punished responding. In the subsequent experiments, response suppression learning was assessed after injecting 11- and 17-day-old rat pups with the specific DA D-2 agonist, LY 171555 (0.005-, 0.01-, and 0.1-mg/kg, i.p.), or the specific DA D-2 antagonist, sulpiride (5.0-, 15.0-, and 50.0-mg/kg, i.p.). LY 171555 enhanced the punished responding of both the 11- and 17-day-old rat pups; whereas, sulpiride increased the punished responding of the 17-, but not the 11-day-olds. In four additional experiments, the effects of LY 171555 and sulpiride on the locomotor activity, nociception, and reinforcement processes of 17-day-old rat pups was assessed. Rat pups given LY 171555 (0.01 mg/kg, i.p.) exhibited enhanced locomotor activity and a trend towards hyperanalgesia using a hot plate task. Sulpiride (15.0 mg/kg, i.p.) completely antagonized LY 171555's activity enhancing effects and had hyperalgesic properties. In two experiments, sulpiride did not affect the nonpunished appetitive responding of the 17-day-olds; whereas, haloperidol-treated pups responded on fewer reinforced trials than did saline-treated pups. Therefore, these results indicate that the response suppression learning of 17-day-old rat pups is mediated, at least partially, by a DAD-2 receptor system, and that D-2 receptors are also involved in the locomotor activity and nociceptive responses of young rat pups.

Animals↗
PubMed1990

Dopamine antagonists produce an age-dependent increase in the responding of the young chick.

In three experiments the effects of dopamine receptor antagonists on response-contingent punishment and autoshape learning of 1- and 4-day-old chicks were determined. In the first two experiments, 1- or 4-day-old chicks (N = 120) were trained to key-peck for heat reward and then injected intraperitoneally (ip) with either haloperidol (1.5, 2.5, or 5.0 mg/kg) or saline (Experiment 1) and with either haloperidol (2.0 mg/kg), sulpiride (50 mg/kg) or saline (Experiment 2) 30 min before a 96-trial response-contingent punishment session. In Experiment 3, 1- and 4-day-old chicks (N = 48) were injected ip with saline or haloperidol (2.0 mg/kg) 30 min prior to a 30-trial autoshape learning session. In both the punishment and appetitive tasks 1-day-old chicks pretreated with either haloperidol (1.5 to 2.5 mg/kg) or sulpiride showed a significant increase in key-peck responding compared with their saline injected controls. In contrast, 4-day-old chicks given either haloperidol (2.0 mg/kg) or sulpiride did not differ significantly from saline treated chicks on the punishment task, and on the autoshape task haloperidol-treated 4-day-old chicks responded on fewer trials than did their saline controls. These results indicate that dopaminergic synaptic transmission in the young chick as measured by dopamine D2 receptor blockers is functionally different at 1 compared with 4 days of age.

Age Factors↗
PubMed1994

Development of manipulation in capuchin monkeys during the first 6 months.

This study describes the orderly changes in manipulation over the first 6 months in capuchin monkeys (Cebus apella). By 6 months of age, all the basic forms of manipulation seen in adults have appeared. Actions that occur frequently in the first 8 weeks are gentle and involve sustained visual orientation and aimed reaching. Later actions are more vigorous, and involve grasping. Large increases in the rate of activity are evident over the period of development studied. The increase from the first 8 weeks to the second may be due to (a) an increase in the amount of time spent alert and active, (b) a decrease in the amount of time spent in a ventral position, (c) improvements in postural control and stamina and (d) the onset of independent locomotion. Changes in form can be attributed primarily to postural factors and to neuromuscular development (precisely aimed and controlled movements appearing in the 5th and 6th months).

Aging↗
PubMed1994

Social and nutritional influences on the feeding of ring dove squab.

The effects of food deprivation on ring dove squabs' begging and pecking was examined during the period of transition from dependent to independent feeding. Food-deprived squabs begged more, pecked more, and were fed more by their parents than nondeprived squabs. When deprived, young squab primarily beg for food and older squab primarily peck. This difference may arise from the relative efficiencies of the two feeding responses at different ages. Additionally, parental state exerted control over the amount the squab pecked and begged. Parental food deprivation affected squab pecking, probably because hungry parents pecked more themselves and fed squabs less. Squab begging was not affected by parental food deprivation. However, parental separation from squab affected squab begging, as parents previously without squab were more likely to feed begging squab than were parents who were not separated from squab. Parental separation from squab did not affect squab pecking. The changes in the endogenous and exogenous controls of squab feeding allow for a great deal of plasticity in the transition from dependent to independent feeding.

Aging↗
PubMed2001

Altered response to meta-chlorophenylpiperazine in anorexia nervosa: support for a persistent alteration of serotonin activity after short-term weight restoration.

OBJECTIVE: Patients with anorexia nervosa (AN) have disturbances of appetite and behaviors, such as dysphoria, inhibition, and obsessions, that could be related to altered serotonin activity. To investigate such relationships, we administered meta-chlorophenylpiperazine (m-CPP), a relatively serotonin-specific drug. METHODS: To avoid the confounding effects of malnutrition or weight loss, we studied 12 patients with restricting-type AN between 5 and 17 days after a return to a normal weight and while on a stable dietary intake. We compared them to 12 healthy control women (CW). m-CPP was administered double blind and placebo controlled. RESULTS: Although weight restored, AN women had lower body weight and increased ratings for depression and obsessionality compared with CW. After m-CPP, AN women had an elevation in mood and a reduction in body image distortion when compared with placebo. After m-CPP, groups had similar cortisol, adrenocorticotropin (ACTH), and growth hormone responses whereas AN women had an uncertain reduction in prolactin response. DISCUSSION: These data support other studies that suggest that altered serotonin activity persists after weight restoration in AN patients. The finding that m-CPP temporarily improved mood and reduced body image distortions supports the hypothesis that altered serotonin activity may contribute to the pathophysiology of AN.

Adolescent↗
PubMed1998

The fen-phen finale: a study of weight loss and valvular heart disease.

OBJECTIVE: To assess weight loss, as well as the prevalence of valvular heart disease, in 21 obese women who completed 2 years of treatment by fenfluramine and phentermine (fen-phen) in June 1997. RESEARCH METHODS AND PROCEDURES: Patients were 21 of 22 women who had completed a 1-year, open-label trial of fen-phen combined with lifestyle modification. This study describes the results of a second year of treatment. The presence of valvular heart disease, defined as aortic regurgitation of mild or greater severity and/or mitral regurgitation of moderate or greater severity, was assessed using two-dimensional, color Doppler and pulsed- and continuous-wave Doppler examinations. RESULTS: At 2 years, the 21 patients had a mean reduction in initial weight of 13.9 + 10.0%, which was significantly (p<0.001) smaller than their 1-year loss of 17.1 +/- 8.7%. Nine of 21 patients reported that they took fen-phen irregularly during the last 4 months of the study because of fears of developing health complications. These nine patients had a 2-year weight loss of 8.7 +/- 7.5%, compared with a significantly (p<0.04) larger loss of 17.6 +/- 10.5% for participants who reported taking medication regularly. Six of 20 (30%) patients met criteria for valvular heart disease. None of the six had signs or symptoms of this condition. DISCUSSION: Fenfluramine was withdrawn from the market on September 15, 1997 because of concerns that it was associated with valvular heart disease. The present findings are discussed in terms of the potentially favorable long-term benefits of combining lifestyle modification with weight loss medications that are both safe and effective.

Adult↗