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Explore the source record for details and available documents.
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The organization and evolution of insect societies has amazed natural historians since Aristotle. Charles Darwin considered social insects to be a major difficulty for his theory of evolution by natural selection because they demonstrate a rich diversity of adaptation among sterile workers leading to a complex division of labour, something that should not occur if variation in individual reproductive success is the grist for the mill of natural selection. This article shows how division of labour can self-organize from groups of cohabiting individuals without the necessity of a past history of natural selection for co-operative behaviour. It then explores how more complex social systems may evolve.
The evidence that NPY is an endogenous neurotransmitter that modulates both sides of the energy equation is clear and compelling. While agreeing with this (and indeed contributing to the growing literature supporting the concept), we have found that the interpretation of the increased food intake stimulated by intraventricular (i.v.t.) NPY is more complex than first appears. We discuss evidence suggesting that NPY additionally (and presumably at other receptor populations in the brain) causes sensations that produce aversion or illness. Specifically, the i.v.t. administration of NPY at doses that stimulate eating also cause the formation of a conditioned taste aversion and the animal engages in a form of pica behavior (kaolin consumption). It also suppresses an otherwise robust increase of sodium consumption. We discuss evidence suggesting that whereas NPY activates feeding behavior by stimulating the complex sequence of behaviors beginning with the seeking and finding of food and ending with food ingestion, NPY does not stimulate increased eating in the absence of the anticipatory preliminary behaviors. Finally, we briefly review evidence suggesting that whatever sensation is aroused by i.v.t. NPY, it is not necessarily the same sensation that is aroused when animals are food-deprived. Hence, one must be cautious in interpreting NPY as solely an orexigen.
The involvement of dopaminergic systems in appetitive and ingestive feeding behaviors was investigated in two experiments. Conditioned preparatory responses to a conditional stimulus (CS+) signaling delivery of a meal were attenuated in rats by doses of 0.4 and 0.6 mg/kg of the dopamine receptor antagonist pimozide. In contrast, animals responded in a normal fashion following the delivery of food. Similarly, in a separate study, the 20-min free-feeding intake of liquid diet by rats that had been deprived of food for 23 hr was unaffected by doses of pimozide as high as 0.6 mg/kg. These findings are consistent with the involvement of dopamine in the production of preparatory behaviors elicited by incentive stimuli.
The authors investigated the behavioral actions of vasotocin (VT) in castrated testosterone-treated male Japanese quail. The appetitive and consummatory components of sexual behavior as well as the occurrence frequency of crows were inhibited, in a dose-dependent manner, by injections of VT. The authors observed opposite effects after injection of the V1 receptor antagonist, dPTyr(Me)AVP. Lower doses of VT were more active after central than after systemic injection, and effects of systemic injections of VT were blocked by a central injection of dPTyr(Me)AVP. The behavioral inhibition was associated with a modified diuresis after systemic but not central injection. These results provide direct evidence that VT affects male sexual behavior in quail by a direct action on the brain independent of its peripheral action on diuresis.
A taxonomy of the movement patterns of the 8 flexible arms of octopuses is constructed. Components consist of movements of the arm itself, the ventral suckers and their stalks, as well as the relative position of arms and the skin web between them. Within 1 arm, combinations of components result in a variety of behaviors. At the level of all arms, 1 group of behaviors is described as postures, on the basis of the spread of all arms and the web to make a 2-dimensional surface whose position differs in the 3rd dimension. Another group of arm behaviors is actions, more or less coordinated and involving several to all arms. Arm control appears to be based on radial symmetry, relative equipotentiality of all arms, relative independence of each arm, and separability of components within the arm. The types and coordination of arm behaviors are discussed with relationship to biomechanical limits, muscle structures, and neuronal programming.
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Thyroidectomized cats and cats with pontile lesions exhibit the same abnormal grooming behavior. Investigations were conducted to determine whether the abnormal grooming behavior in cats with pontile lesions was attributable to a hypothyroid condition. Administration of thyroid hormones abolished the abnormal behavior of thyroidectomized cats but was without effect in cats with pontile lesions. Studies of brain and blood levels of thyroid hormones in cats with pontile lesions failed to detect any differences from normal cats, and normal effects of thyroid hormones on evoked potentials to light flashes and to clicks were obtained in cats with pontile lesions. It was concluded that any thyroid dysfunction that may exist in the cats with pontile lesions was not involved in the genesis of the abnormal grooming behavior. Because the abnormal grooming behavior fluctuates rhythmically during the year, an endocrine hypothesis was entertained as the source of the fluctuations; endocrine concomitants of the abnormal behavior were investigated with longitudinal studies. The urinary excretion of 11-hydroxycorticoids exhibited a significant negative correlation with the abnormal behavior. When compared with that of normal cats, the plasma level of 11-hydroxycorticoids of thyroidectomized cats was significantly decreased. Intramuscular injections of 11-hydroxycorticoids abolished the abnormal behavior in both thyroidectomized cats and cats with pontile lesions. These results considered together with previous findings indicate that thyroidectomy and pontile lesions induce similar changes in 11-hydroxycorticoid and serotonergic functions-changes that are critical features of the physiological bases of the abnormal grooming behavior in both groups.
Previous research reported that rats responding for 1% liquid-sucrose reinforcement when 32% sucrose reinforcement is upcoming will decrease their response rate (contrast) if licking is the dependent measure and increase their response rate (induction) if pressing a lever is the dependent measure. The present study investigated whether induction could be observed when licking served as the dependent measure and whether induction in lever pressing and contrast in licking behaviour could be concurrently observed. Experiment 1 found induction when rats licked to earn the rewards but consumed them at a location separate from the spout licked to earn them. Experiment 2 also found induction when rats earned (and consumed) rewards by licking the same spout throughout the session. Experiment 3 separately measured instrumental lever pressing for sucrose rewards and licking the sucrose during the reward period. We found that both measures increased for 1% sucrose when 32% sucrose reinforcement was upcoming. The present results indicate that the type of response is not the sole determinant of whether contrast or induction is observed. Rather, they suggest that other procedural details, such as the location of reinforcer delivery, influence which effect is observed. The results also indicate that associative processes underlie the appearance of induction in responding for 1% sucrose.
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The ability of Antabuse (disulfiram) to influence ethanol consumption and learning in harnessed honey bees was investigated. In the first series of experiments a factorial design was used with 5 levels of ethanol concentration (0%, 1%, 5%, 10%, 20%), 4 doses of Antabuse (0, 37 microg/g, 3.7 microg/g, .37 microg/g), and 2 testing intervals (1 min., 10 min.). Animals were fed a single 1 microl dose of Antabuse and contact time with an ethanol solution measured. A second series of experiments investigated the influence of Antabuse on the formation of Pavlovian conditioning of the proboscis extension reflex. A factorial design was used with two levels of training (paired, unpaired), three levels of ethanol (0%, 1%, 5%), and 2 levels of pretreatment (distilled water, 3.7 microg/g). Analysis of the consumption experiments indicate that pretreatment with Antabuse reduces ethanol intake, although there was substantial variability. The findings of the Pavlovian experiments suggest that pretreatment with Antabuse significantly reduced responding to a CS signaling the availability of ethanol.