Food wresting and dodging: Strategies used by rats (Rattus norvegicus) for obtaining and protecting food from conspecifics.

We describe two previously undocumented stereotyped behaviors used by group-housed laboratory rats to obtain and protect food. Rats in social groups with limited access to food will attempt to obtain food by wresting it away from each other. To gain food, a rat will approach a feeding rat from behind, walk along its side, and then attempt to seize the food that it holds. To protect the food, the victim dodges laterally away from the approaching rat. The dodge effectively positions the robber to the rear and gives the victim time to continue eating. Contralaterally directed dodges take two general forms: One type involves a body turn and rear leg step that carries the rat about 19 cm in an arc of about 175° contralateral to the robber; the food is held in the forepaws. The second type involves a body turn and rear leg step that carries the rat in a longer arc; the food is transferred to the mouth and then back to the forepaws. Wresting attempts and dodges made by male and female rats are not different. The wrester–dodge relation can be used as a laboratory paradigm for the study of features of social dominance, for the investigation of the neural substrate of orienting behavior, and for investigating other aspects of social behavior or parasitic behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Food wrenching and dodging: A neuroethological test of cortical and dopaminergic contributions to sensorimotor behavior in the rat.

Sensorimotor behavior in unilateral decorticate and unilateral dopamine-depleted rats was studied in a naturally occurring social interaction in which rats compete for food with relatively stereotyped species-typical responses. In the interaction a "robber" attempts to wrest food from a feeding "victim," which in turn protects the food by making rapid contralateral dodges. Hemidecortication abolished dodging to food wrenching attempts made by a rat approaching contralaterally to the lesion, so that the food was stolen, but recovery occurred between 15 and 60 days after surgery. Use of the side contralateral to the lesion to wrest food was moderately impaired, and recovery of food wresting was more rapid than recovery of dodging. Unilateral dopamine depletion produced dodging impairments to food-wresting attempts that were made both ipsilateral and contralateral to the side of the lesion, and the deficits endured over 60 test days. The food was frequently lost to food-wrenching attempts made contralateral to the lesion, whereas the direction of dodges to approaches ipsilateral to the lesion was reversed. Food wresting was also bilaterally impaired. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A kinematic analysis of evasive dodging movements used during food protection in the rat (Rattus norvegicus): Evidence for sex differences in movement.

Food-deprived rats (Rattus norvegicus) will protect their food by dodging away from a conspecific. A detailed kinematic analysis of these movements in adult rats shows that each sex uses sex-typical movements. Females move their snout through a greater spatial curvature, and their snout achieves a greater velocity, relative to the pelvis, than males. Males make more hindpaw steps than females and achieve a more simultaneous movement of the fore- and hindquarters. This suggests that females pivot around a point more posterior on the body than males. The finding that functionally similar patterns of movement have a sex-specific organization provides a new dimension for the study of sex differences. These differences are discussed in relation to sex differences in sex-typical behaviors, associated body structure, and neural control. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A kinematic analysis of sex-typical movement patterns used during evasive dodging to protect a food item: The role of testicular hormones.

Feeding rats dodge laterally away from a conspecific attempting to steal their food. Dodges by female and male rats differ in their composition of movement. Females pivot around a point more posterior on the longitudinal axis than do males, producing a greater amount of movement of the snout in relation to the pelvis. This experiment examined the role of testicular hormones on these sex-typical movement patterns. Castration at weaning (21 days) does not affect the male-typical pattern. Neonatal testicular hormone manipulation, however, does alter sex-typical patterns of movements. Whereas castration neonatally makes male rats more female-like, injections of neonatal female rats with testosterone propionate make them more male-like. These findings suggest that the organization of sex-typical patterns of dodging involves perinatal action of gonadal hormones. Results are discussed in relation to anatomy, neural structure, and the role of gonadal hormones during development. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neonatal and Pubertal, but Not Adult, Ovarian Steroids Are Necessary for the Development of Female-Typical Patterns of Dodging to Protect a Food Item.

Rats protect food by dodging horizontally away from a conspecific. Females and males use different movement and stepping patterns to execute a dodge. An unresolved question is whether exposure to ovarian steroids in females is necessary for the development of the female-typical pattern. Females ovariectomized neonatally and prior to puberty use a combination of male and female tactics. Pregnant females, however, use a female-typical pattern of dodging, suggesting that the patterns used by prepubertal ovariectomized females are not due to their increase in body mass. Thus, the contribution of ovarian steroids to the development of female-typical patterns of behavior needs to be studied further at both a behavioral and neural level with regard to the organization of movement. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Genetic influences on digging behaviors in mice (Mus musculus) in laboratory and seminatural settings.

Examined digging behaviors of several inbred strains of laboratory mice and some of their crosses in 3 contexts. In laboratory burrow boxes, C57BL/6Abg mice constructed more sophisticated burrow systems than did BALB/cAbg mice. Their F? hybrids built burrow systems more complex than either parental strain. The same pattern of genetic influence was observed in an outdoor pen. In an escape task that required digging, BALB/c mice escaped more quickly than did C57BL/6 mice; their F? hybrids showed dominance toward the BALB/c phenotype. Results indicate that behavioral polymorphisms in digging behavior, which may relate to habitat selection, have a genetic basis. The dominance and overdominance toward the better digging parental strain in each type of task suggest the possible evolutionary importance of these digging behaviors. (18 ref) ?55 (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Paternal behavior in the male Long-Evans rat (Rattus norvegicus).

Five studies examined the paternal behavior of monogamously housed male and female, individually housed male, and virgin male and female Long-Evans rats. Findings indicate that males cohabiting monogamously with females showed low levels of pup contact and parental behavior, and the frequency of these behaviors did not increase with experience, possibly because the lactating females kept the males away from the pups. When presented with pups in their own cage, sexually experienced and naive males did not differ in the latency or frequency of parental behavior, and both groups showed more parental behavior than monogamously housed males. Males that had formerly exhibited infanticide showed as much parental behavior as noninfanticidal males. The frequency of pup contact and parental behavior increased as the pups grew older. Although virgin males showed the same latency as virgin females to exhibit parental behaviors, females showed these behaviors more frequently than males. Results suggest that the responsiveness of noninfanticidal male rats to infants may depend on the test situation and the age of the infants. (45 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Individual differences in the behavior of rats (Rattus norvegicus).

Male and female hooded rats were evaluated individually for performance in burrowing, food hoarding, exploration, and insect predation in the laboratory. The results were that (a) performance in each of these behaviors was distributed over a wide range; (b) females as a group had significantly better burrowing and insect predation performance than did males; (c) there were significant correlations between individual performance in each of these behaviors in two series of tests held 30 days apart; and (d) no evident and systematic correlations between individual performance in different kinds of behavior were detected. These and other results in the literature support the idea that behavioral performance in nonprimate mammals is not stereotyped. On the contrary, individuals tend to have conspicuous behavioral interactions with the environment, and this characteristic tends to be stable, under our conditions, for periods of at least 1 month. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differences in the liability to self-administer intravenous cocaine between C57BL/6 x SJL and BALB/cByJ mice

Application of animal models of psychostimulant abuse for experimentation in mice is becoming increasingly important for studying the contribution of genetic differences, as well as the roles of selected (targeted) genes, in specific behaviors. The purpose of this study was to investigate strain differences in cocaine self-administration behavior between C57BL/6 x SJL hybrid mice and BALB/cByJ mice. These two strains were chosen because BALB/cByJ mice have a well-developed behavioral pharmacological profile, and hybrid strains on a C57BL/6 background are commonly used for generating transgenic expressing and knockout mutant mice. C57BL/6 x SJL mice dose-dependently acquired cocaine self-administration (1.0 mg/kg/injection but not 0.25 mg/kg/injection) by responding selectively in the active nose-poke hole and maintaining stable levels of daily drug intake; they also exhibited a characteristic inverted-U-shaped cocaine dose-effect function. BALB/cByJ mice failed to acquire cocaine self-administration at either dose under the same test conditions. The strain differences observed in self-administration did not seem to be attributed to other behavioral differences because the two strains exhibited similar amounts of spontaneous nose-poking in the absence of reinforcers, and BALB/cByJ mice responded more than C57BL/6 x SJL mice in a food-reinforced nose-poke operant task. Importantly, the dose-effect function for the motor stimulating effects of cocaine (3.8-30 mg/kg intraperitoneally) suggests enhanced sensitivity but reduced efficacy of cocaine in stimulating motor activity in BALB/cByJ mice relative to the C57BL/6 x SJL hybrid mice. These results indicate that the decreased liability of BALB/cByJ mice to acquire cocaine self-administration is not the result of differences in spontaneous activity or performance, but may reflect different sensitivities to the reinforcing, or rate-disrupting, properties of cocaine. The data support an influence of genetic background in the liability to self-administer cocaine. Thus, a hypothesis is proposed that the decreased liability of BALB/cByJ mice to acquire cocaine self-administration is related to differences in brain monoamine systems linked to the high "emotionality" profile of BALB/c mice in novel or fearful situations, including perhaps cocaine administration.     

Strain and sex differences on olfactory discrimination learning in C57BL/6J and DBA/2J inbred mice (Mus musculus).

In this study, the authors explored potential strain and sex differences in nonspatial cognitive ability. Beginning around 90 days of age, male and female C57BL/6J (C57) and DBA/2J (DBA) inbred mice (Mus musculus) were tested on a task of simple odor discrimination learning with 3 repeated reversals. Males learned the task more readily than females, and DBA mice learned the task more readily than C57 mice. All differences became evident after repeated testing. Similarity of perseveration measures indicated the differences were not due to inhibitory deficits. Instead, a phase analysis localized differences to a transitional period of reversal learning. Females increased transitional errors that more likely indicated adaptive sampling strategies than memory failures. C57 females used this strategy indiscriminately, but DBA females sampled as a function of environmental uncertainty. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Characteristics of thirst and sodium appetite in mice (Mus musculus).

Intakes of water and NaCl solution were examined in mice following treatment with agents that stimulate or mimic components of the renin-angiotensin-aldosterone system. Injections of angiotensin II or isoproterenol produced little water intake compared with robust responses to either intracellular dehydration or extracellular dehydration induced by treatment with polyethylene glycol. In studies on appetite for NaCl solution, mice exhibited no spontaneous preference for NaCl solution over water and did not change this preference during treatment with deoxycorticosterone acetate, a sodium-deficient diet, or after adrenalectomy. Plasma concentrations of aldosterone were increased in intact mice fed a sodium-deficient diet but not eliminated by adrenalectomy. Acute treatment with furosemide in combination with a sodium-deficient diet stimulated an appetite for NaCl solution. Chronic oral administration of an angiotensin I converting enzyme inhibitor failed to induce a NaCl appetite. Findings show that mice are refractory to the induction of water or NaCl intake by stimuli of the renin-angiotensin-aldosterone system, highly effective in rats, suggesting that there may be major differences among rodents in hormonal determinants of behaviors related to hydromineral homeostasis. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Social behavior in Fmr1 knockout mice carrying a human FMR1 transgene.

Fragile X syndrome (FXS) results from the loss of expression of the fragile X mental retardation (FMR1) gene. Individuals affected by FXS experience many behavioral problems, including cognitive impairment, hyperactivity, social anxiety, and autistic-like behaviors. A mouse model of Fmr1 deficiency (Fmr1KO) exhibits several similar behavioral phenotypes, including alterations in social behavior. In an earlier study, Fmr1 knockout mice carrying a yeast-artificial chromosome (YAC) transgene that over-expresses normal human FMRP (KOYAC) showed a correction or overcorrection of some behavioral responses, such as hyperactivity and anxiety-related responses. This report presents results from a study examining transgenic rescue of abnormal social responses in Fmr1KO mice. Relative to their wild-type (WT) littermates, Fmr1KO mice made more active social approaches to standard C57BL/6 partner mice in a direct social interaction test, a result consistent with a previous study. KOYAC mice showed fewer active approaches to partners than the WT or Fmr1KO littermates, indicating correction of this phenotype. This finding expands the number of murine behavioral responses caused by Fmr1 deficiency and corrected by overexpression of human FMRP. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of the nonagouti pelage-color allele on the behavior of captive wild Norway rats (Rattus norvegicus).

The objective of the present study was to determine the extent to which the nonagouti pelage-color allele influences selected behaviors (including docility) of the wild Norway rat. Agouti and nonagouti (black) littermates were compared in tests for handling, open-field behavior, platform jumping, and response to a novel food item, all of which clearly differentiate wild and domestic rats. Nonagouti rats were significantly easier to approach, capture, and handle than their agouti sibs. However, differences between agouti and nonagouti rats for the other variables studied were not significant. Although the presence of the nonagouti allele cannot fully account for the behavioral differences between wild and domestic Norway rats, it may have facilitated the domestication of this species by improving ease of handling. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Poison-based taste aversion learning in deer mice (Peromyscus maniculatus bairdi).

Used a series of experiments to test the ability of 219 adult Peromyscus mice to form learned taste aversions. It was found that (a) the mice acquired a strong aversion after a single flavor/toxicosis pairing, (b) naive mice drinking a LiCl solution apparently began to experience toxic effects within 90 sec after the beginning of consumption, (c) the mice acquired a total aversion after a single flavor/delayed illness pairing when high doses of toxin were employed, and (d) the aversion produced by a single flavor/delayed-illness pairing was specific to the flavor paired with illness and was dependent on the contingency between the flavor and illness. Although these responses are qualitatively similar to those reported for domestic rats, the mice formed considerably weaker aversions than those previously reported for laboratory rats tested with the same weight-specific doses of LiCl. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feeding, activity, and body temperature following 6-hydroxydopamine lesions in diabetes (db/db) mice.

Reductions in central catecholamines produced by intraventricular injections of 6-hydroxydopamine (6-OHDA) cause weight loss and decreased plasma glucose in diabetes (db/db) mice. The present study examined the effects of this treatment in short-term (64-day) and long-term (120-day) survival groups of female diabetes (C57 BL/KsJ-db/db) and lean mice. Phenotypically heterozygotes (db/m) and homozygotes (m/m) were used as controls. Diabetes Ss treated with 6-OHDA decreased food intake, lost weight, and maintained a lower weight than vehicle-treated controls until vehicle-treated Ss began to enter the terminal stages of the syndrome, indicated by a loss of body weight. Diabetes Ss given 6-OHDA lost weight despite reduced body temperatures and activity levels. Blood glucose levels were always lower in 6-OHDA than in ad lib fed vehicle-treated db/db Ss. The 6-OHDA treatment also improved pancreatic islet granulation. Pair feeding vehicle-treated with 6-OHDA-treated db/db Ss did not halt weight gain in the vehicle-treated group. However, measurement of carcass fat indicated similar losses in db/db-6-OHDA Ss and vehicle-treated Ss when the vehicle group was pair-fed with lean controls. Treatment with 6-OHDA produced long-term improvement in the diabetes syndrome, but the decreased body weight of the 6-OHDA-treated diabetes Ss could not be completely accounted for by changes in food intake or energy expenditure. (43 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Copulatory behavior of roof rats (Rattus rattus).

Investigated the copulatory behavior of a total of 71 male and 48 female roof rats (Rattus rattus) in 3 experiments. In Exp I, females were brought into behavioral estrus with exogenous hormones, and each pair was observed until 30 min elapsed without copulation. Roof rats appeared to be similar to laboratory rats (Rattus norvegicus) with regard to basic motor patterns of copulation, quantitative measures of copulation, behaviors accompanying copulation, and postejaculatory ultrasonic vocalizations. Only (a) patterns of tail rattling in females, (b) climbing and allogrooming in both sexes, and (c) an ability to ejaculate on a single insertion by males were observed in roof rats but not reported for laboratory rats. Exps II and III were designed to assess the role of various components of the copulatory pattern of male roof rats on the induction of pregnancy in normally cycling young females. A single ejaculation preceded by an abnormally high number of intromissions or 3 normal ejaculatory series maximized the incidence of pregnancy, whereas 1 normal ejaculatory series or 1 ejaculation preceded by an abnormally low number of intromissions did not. (28 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Maternal performance of inbred and hybrid laboratory mice (Mus musculus).

60 primiparous mice from 3 inbred strains (A/J, DBA/2J, C57BL/6J) and their reciprocal crosses were subjected to various tests of maternal behavior. During pregnancy, S was placed in a seminaturalistic environment, and her nest-building activity was assessed. Following parturition, S's retrieval behavior was measured under conditions that placed conflicting demands on her behavioral repertoire. Results indicate that there were both qualitative and quantitative differences between inbred and hybrid Ss. Prenatal nest-building activity showed heterosis on various measures of relevant environmental manipulations. The retrieval data suggest that inbred Ss were less able to integrate their behavior into a coherent pattern. The level of inbreeding of the pups had no significant effect on the aspects of maternal behavior measured. (20 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Stimulation of glycogenolysis by beta adrenergic agonists in skeletal muscle of mice with the phosphorylase kinase deficiency mutation (I strain)

The mechanism by which beta adrenergic agonist stimulate glycogenolysis in intact skeletal muscle was investigated in mice with the phosphorylase kinase deficiency mutation (I strain). Although extracts of I strain diaphragm muscle had only 3.7% of the phosphorylase kinase activity found in extracts of the control strain (C57BL), incubation of I strain hemidiaphragms in Krebs-Ringer bicarbonate buffer with either isoproterenol or epinephrine resulted in a stimulation of the rate of glycogenolysis. In C57BL diaphragms, the EC50 values for isoproterenol and epinephrine were 2 and 14 nM, respectively. With I strain diaphragms, dl-isoproterenol or l-epinephrine stimulated glycogenolysis as a linear function of the log of the drug concentration with no apparent plateau of response up to concentrations of 30 to 40 mugM. For each 10-fold increase in drug concentration, isoproterenol and epinephrine stimulated glycogenolysis in I strain muscles an additional 0.37 to 0.42 mg/g/hr, a slope in the concentration-response relationship of 0.17 and 0.37, respectively, of that measured in C57BL diaphragms at concentrations around the EC50. The highest glycogenolytic response measured in I strain hemidiaphragms (at 40 mugM isoproterenol) was 80% of the maximal catecholamine-stimulated glycogenolysis in C57BL diaphragms. Both 4 nM and 4 mugM isoproterenol, in a concentration-dependent manner, stimulated phosphorylase b to a conversion in I and C57BL diaphragms and increased cyclic adenosine 3':5'-monophosphate (cyclic AMP) concentrations. The glycogenolytic response to 10.1 nM dl-isoproterenol in both I and C57BL diaphragms was blocked by 34 nM l-propranolol but not by 34 nM d-propranolol. The response to 4 mugM isoproterenol was enhanced by the cyclic nucleotide phosphodiesterase inhibitors papaverine (27 mugM) or dl-4-(3-butoxy-4-methoxybenzyl)-2-imidazolidinone (Ro 20-1724, 3 mugM). From the results of these studies, we conclude: 1) Catecholamines stimulate glycogenolysis in skeletal muscle of I mice, as in C57BL mice, by interacting with the beta adrenergic receptor, thereby increasing tissue cyclic AMP concentrations and stimulating phosphorylase b to a conversion. 2) alternative hypotheses for the mechanism of the catecholamine-stimulated decrease in glycogen concentration in I skeletal muscle-inhibition of glycogen synthesis, hyposia and 5'-AMP stimulation of phosphorylase b activity-have been ruled out. 3) the activity of the mutant phosphorylase kinase, although it is only 3.7% of that in extracts of C57BL muscle, is sufficient to produce phosphorylase b to a conversion and thereby account for the glycogenolytic response of I strain muscle to catecholamines.     

Measurements of the behavioral effects of albino mutation in mice (Mus musculus): Comparisons of coisogenic inbred and hybrid lines.

The effects of the albino gene on mouse behavior were examined, particularly its possible interactions with nonallelic genes (epistasis). More generally, the possible effects of genetic background (inbreeding depression or hybrid vigor) on the effects of the mutation were also considered. Tasks requiring either predominantly motor or predominantly cognitive capacity were studied for coisogenic albino and pigmented mice from either an inbred strain (C57BL/6 c/c vs C57BL/6 +/c) or an F? heterozygous generation (F? c/c vs F? +/c) from a BALB/c?×?C57BL/6 +/c cross. Results show a clear albino gene effect in the 2 lines and provide further evidence that the gene is the effective factor. There was no significant interaction between the mutation and the genotypic group (C57BL/6 or F?), which indicates that the effects of the mutation act approximately in an additive fashion between loci in these groups. (13 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Comparison of predatory behaviors of deer mice (Peromyscus maniculatus) and grasshopper mice (Onychomys leucogaster).

Deer mice (Peromyscus maniculatus) and grasshopper mice (Onychomys leucogaster) are morphologically similar and coexist in many habitats. I compared certain aspects of their insect-catching behavior for insights into the ecology and evolution of predatory behavior in rodents. The predatory attack of grasshopper mice appears more specialized than that of deer mice: The former attacked faster and more consistently, used their paws more to seize a fast-moving prey, and showed more resistance to the inhibitory effects of novel, aversive, or intimidating stimuli from a prey than did the latter. Nonetheless, deer mice are effective insect predators and exhibit a more developed predatory attack than hamsters, whose attack response is considered typical of many rodents. Grasshopper mice exhibit behavioral and morphological adaptations expected of a carnivorous mammal, and these adaptations also aid in its competition for insect prey with other rodents. (PsycINFO Database Record (c) 2010 APA, all rights reserved)