Maternal separation alters social odor preference development in infant mice (Mus musculus).

This study examined whether daily periods of maternal separation during the first two weeks of life would decrease attraction to familiar nest odors in CD-1 mice 10 and 14 days old. We also investigated whether placing a group of mice (Mus musculus) in nest shavings during the 180-min separation period would mitigate possible separation-induced deficits. The maternal separation procedure has been widely used as a rodent model for the effects of inconsistent or inadequate early caretaking on human development. From postnatal day (PND) 1 to 14, litters were separated from the dam, but not littermates for either 15 or 180 min, or were facility-reared controls. Control, facility-reared mice preferred home-cage nest to clean familiar shaving odors on PND 10, but not PND 14. In contrast, home-cage nest odors attracted maternally separated mice on both test days. Our results suggest that maternal separation maintains the olfactory tether to the nest in a period when the attraction normally begins to weaken. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Bitter avoidance in guinea pigs (Cavia porcellus) and mice (Mus musculus and Peromyscus leucopus).

Rejection of bitter substances is common in many species and may function to protect an animal from ingestion of bitter-tasting toxins. Since many plants are bitter, it has been proposed that high tolerance for bitterness would be adaptive for herbivores. Earlier studies conducted on herbivorous guinea pigs (Cavia porcellus) have been used to support this proposal. We tested guinea pigs with bitter plant secondary metabolites (salicin, caffeine, quinine hydrochloride) and bitter protein hydrolysates (two types of hydrolyzed casein, hydrolyzed soy) in a series of two-choice preference tests. For comparison, we tested two nonherbivorous mouse species (Mus musculus and Peromyscus leucopus). Guinea pigs did show weaker avoidance of quinine hydrochloride than did the mice, confirming predictions generated from earlier work. However, guinea pigs had similar responses to caffeine as did Peromyscus. Both of these species showed weaker avoidance responses than Mus to 10 mM caffeine. For salicin, guinea pigs were the only species to avoid it at 10 mM and their preference scores at this concentration were significantly lower than for the two mice species. Guinea pigs avoided all of the protein hydrolysates more strongly than the other species. Responses to the protein hydrolysates did not reflect the patterns observed with the simple bitter compounds, suggesting that other properties of these complex stimuli may be responsible for guinea pig avoidance of them. Our results suggest caution in accepting, without further empirical support, the premise that guinea pigs (and herbivores in general) have a generalized reduced bitter sensitivity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Male acceleration of puberty in female mice (Mus musculus).

Nine experiments investigated various aspects of the acceleration of puberty in female ICR/Alb house mice (N?=?754) produced by the presence of a male mouse or urine from males. Grouping males had no effect on the urinary chemosignal that accelerates puberty, except that urine from dominant males produced greater acceleration than urine from subordinates. Young female mice must be exposed to the male urine for at least 2–3 hrs/day or to the presence of a male for 1 hr/day to produce acceleration of first vaginal estrus. Females were accelerated to the same extent in attaining puberty whether treated with urine from the same male or a different male each day. Urine from the father or a full brother, or the presence of those close relatives, exerted no differential acceleratory or retarding effect on puberty when compared with urine from or the presence of unrelated males. Excreted or bladder urine from adrenalectomized males accelerated puberty to the same extent as urine from intact males, but the presence of an adrenalectomized male did not produce the same degree of acceleration as when an intact male was present. Behavioral observations indicate that adrenalectomized males pursued young females less and attempted fewer mounts during a brief test period. Implications are noted for the understanding of both the mechanisms of acceleration of puberty in the house mouse and the population and reproductive biology of these mice. (35 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Familiarity with conspecific odor and isolation-induced aggressive behavior in male mice (Mus domesticus).

60 male Swiss CD-1 mice were isolated for 24 days. In the isolation group mice were exposed to their own odor; in the familiarity group mice were familiarized with pairmates' odor by daily exchange of bedding; and in the unfamiliarity group Ss (exposed) were familiarized with pairmates' odor, whereas the pairmates (nonexposed) were familiarized with odors of other isolated mice. Aggressive behavior was scored during 20-min sessions. Familiarity with the pairmate's odor (familiarity and exposed subgroups) caused an enhancement of aggressive behavior, shown by the highest frequency of tail rattling and offensive upright posture and by a decrease in latency to the 1st attack. Nonexposed Ss showed high values of submissive upright posture, screaming, fleeing, and freezing. The results suggest that dominantlike behavior, acquired in social isolation, may be directed toward a conspecific whose odor is familiar. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Differential effects of visual context on pattern discrimination by pigeons (Columba livia) and humans (Homo sapiens).

Three experiments examined the role of contextual information during line orientation and line position discriminations by pigeons (Columba livia) and humans (Homo sapiens). Experiment 1 tested pigeons' performance with these stimuli in a target localization task using texture displays. Experiments 2 and 3 tested pigeons and humans, respectively, with small and large variations of these stimuli in a same-different task. Humans showed a configural superiority effect when tested with displays constructed from large elements but not when tested with the smaller, more densely packed texture displays. The pigeons, in contrast, exhibited a configural inferiority effect when required to discriminate line orientation, regardless of stimulus size. These contrasting results suggest a species difference in the perception and use of features and contextual information in the discrimination of line information. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual discrimination learning and strategy behavior in the fat-tailed dunnarts ( Sminthopsis crassicaudata ).

Fat-tailed dunnarts (Sminthopsis crassicaudata) were trained on visual discrimination learning-set, reversal-set, and spatial delayed-alternation tasks. The learning set involved 36 2-way black-and-white pattern discriminations and 5 probe reversals. Ten reversals of a black-and-white pattern discrimination were followed by 5 novel tasks. Spatial alternation was tested at delays up to 20 s. Learning-set and reversal-set formation, including 1-trial learning and spontaneous transfer from learning set to reversals and vice versa, was found. Learning-set-experienced dunnarts showed no retention of previously learned tasks 1 week after testing but demonstrated consistently high Trial 2 performance, indicating the retention of a response strategy. Delayed-alternation tasks were learned up to 10-s delays. These results provide the first evidence of a visually guided "win-stay, lose-shift" strategy in a marsupial. (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)     

Effects of male social status on reproductive success and on behavior in mice (Mus musculus).

Differences in reproduction as well as in behavior in the presence of females were evaluated according to dominant and subordinate male rank in albino mice, in the temporary absence of each male's antagonist. Dominant males reproduced more successfully than subordinate males. Subordinate males were generally inactive, except for displacement activities, during the first 15 min they were exposed to female partners. These findings suggest that mechanisms other than male–male interference or mating order may be operating or influencing behavior and reproductive results. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Behavioral development and strain differences in perinatal mice (Mus musculus).

Examined the perinatal development of spontaneous body movements and reflexes in Slc:ICR, C3H/He, and BALB/c mice. Mice were observed from Day 18 (a day before normal parturition) to Day 21.5 of gestation. The developmental changes of spontaneous body movements and reflexes occurred quickly. Strain differences in behavioral development were detected in the duration of spontaneous body movements but not in the occurrence of reflexes. Hybrid mice were more active than their parental strains with regard to duration of spontaneous body movements. The rooting reflex and crossed extensor reflex in hybrid mice occurred more frequently on Day 18 than in their parental strains. These results indicate that the perinatal period is characterized by quick qualitative and quantitative changes in behavioral development and by the appearance of these genetic differences. (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)     

Observational learning of a left-right behavioral asymmetry in mice (Mus musculus).

B6D2F? hybrid mice that were allowed to observe a trained female mouse open a pendulum door to the right (or to the left) to enter a food compartment later solved this problem faster than pupils that had been placed behind a visual barrier. Male pupils that had observed a "left-handed" teacher performed sinistrally; males that had observed a "right-handed" model performed dextrally. Female pupils did not exhibit their demonstrator's laterality. Observational learning may provide a means to maintain certain lateralized behaviors. Such social learning may lead to the emergence of local traditions and to the cultural diffusion of behavioral asymmetries. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Interactions of contact, odor cues, and androgens in strange-male-induced early pregnancy disruptions in mice (Mus musculus).

Novel males can disrupt early pregnancy in female house mice (Mus musculus). In Experiment 1, exposure to novel males disrupted pregnancy, but exposure to male urine did not. In Experiment 2, urine from male or female mice or rats painted on females' noses did not influence pregnancy. In Experiment 3, the conjunction of urine painted on female's noses and vulval stimulation did not affect pregnancy more than water with similar stimulation. In Experiment 4, males housed above females were separated from them by a wire mesh grid; intact males disrupted pregnancy, but castrated ones did not. In Experiment 5, such housing of castrated males or ovariectomized females produced a strong disruption of pregnancy if the stimulus animal was given testosterone but not if it was given oil injections. In Experiment 6, transfers of odorous emissions failed to disrupt pregnancy. Contact and androgen activity are necessary for strange males to disrupt pregnancy. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sibling effects on the behavior of infant mouse litters (Mus domesticus).

We investigated whether the number of same- or other-sex littermates had a graded effect on the occurrence of early solitary play and social play by mouse (Mus domesticus) family units. Sixty litters, reduced at birth to 5 different sex ratios (6 males, 5 males and 1 female, 3 males and 3 females, 1 male and 5 females, and 6 females) were scored in 15-min sessions on postnatal Days 18 and 21. An increasing trend with age was found for run, pounce, popcorn, self-groom, and explore episodes. Type of family unit influenced the occurrence of specific social interactions: One male-5 female and 6 female litters showed more social play than similar male litters. Litters with a balanced sex ratio showed higher exploration than isosexual litters. The results extend previous reports of both social and solitary play in developing laboratory mice and, in contrast with rat data, indicate a marked female primacy in playful social behavior. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Olfactory discrimination of individual littermates in rats (Rattus norvegicus).

Tested the ability of 4 adult male Sprague-Dawley rats to use odors in discrimination among littermates living as a group. Ss were trained in a Y-maze to discriminate the presence of a littermate from its absence. Results from transfer of training in 3 subsequent testing periods indicated that the animals were capable of distinguishing among individuals when relatedness and familiarity were held constant, that this ability was not due to training, and that performance was based solely on odor cues. Results suggest that laboratory rats exhibit odor sensitivities conmensurate with very complex social processes. (17 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The influence of preexperimental experience on social discrimination in rats (Rattus norvegicus).

The authors used laboratory rats (Rattus norvegicus) of known relatedness and contrasting familiarity to assess the potential effect of preexperimental social experience on subsequent social recognition. The authors used the habituation-discrimination technique, which assumes that multiple exposures to a social stimulus (e.g., soiled bedding) ensure a subject discriminates between the habituation stimulus and a novel stimulus when both are introduced simultaneously. The authors observed a strong discrimination if the subjects had different amounts of preexperimental experience with the donors of the 2 stimuli but a weak discrimination if the subjects had either equal amounts of preexperimental experience or no experience with the stimuli. Preexperimental social experience does, therefore, appear to influence decision making in subsequent social discriminations. Implications for recognition and memory research are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Housing pregnant mice (Mus musculus) in small groups facilitates the development of odor-based homing in offspring.

Infant mice (Mus musculus) born to dams housed in isolation throughout pregnancy (IsoPreg) begin differentially approaching homenest bedding over clean bedding on Postnatal Day 6. Offspring of dams housed with 2 other potentially pregnant conspecifics (SocPreg) display such homing behavior on Day 4. Earlier onset of homing reflects facilitated olfactory responsiveness in SocPreg pups, rather than qualitative or quantitative differences in IsoPreg versus SocPreg nest odors, body growth, or motoric capabilities. Exposing pregnant IsoPreg dams to SocPreg bedding also accelerated homing onset in the offspring, though not to the same extent as the full social context. Thus, it appears that the facilitation of homing is mediated through the pregnant dam by a combination of chemical cues and other social stimuli. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Olfactory discrimination of mouse strains (Mus musculus) and major histocompatibility types by humans (Homo sapiens).

Examined, in 5 experiments, whether the olfactory differences apparent to mice are also accessible to humans, using a total of 63 human Ss. In Exp I, Ss were asked to distinguish between the whole-body odors of live mice differing genetically only at the major histocompatibility gene complex (H-2). In Exps II and III, the odor source was mouse fecal pellets, and in Exps IV and V, the odor source was mouse urine. Results reveal that humans can use olfaction to discriminate closely related strains of mice. The possibility that excreted metabolites with characteristic odors may have predated the evolution of an adaptive function for these odors in social communication is suggested. (22 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Short-term early exposure to pups alters infanticide in adulthood in male but not in female wild house mice (Mus domesticus).

Male and female wild house mice (Mus domesticus) were allowed to remain in the cage of their parents until 30–35 days of age. When a second litter was delivered, the first litter was exposed to the younger pups for 2–20 days. In adulthood the male and female mice that had been exposed to pups as juveniles and an additional group that had cohabitated with their parents for the same length of time but were not exposed to pups were tested for infanticidal behavior. The frequency of infanticide by the adult female mice was not significantly different (55% vs. 70%, respectively). In contrast, the adult males that were exposed to pups as juveniles were significantly less likely to kill young in adulthood when compared with males that were not similarly exposed (35% vs. 80%, respectively). These data further demonstrate the strong influence of experience on the expression of infanticide by male mice and its relative unimportance to the expression of female infanticide. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Visual discrimination and reversal learning in rough-necked monitor lizards (Varanus rudicollis).

Reptile learning has been studied with a variety of methods and has included numerous species. However, research on learning in lizards has generally focused on spatial memory and has been studied in only a few species. This study explored visual discrimination in two rough-necked monitors (Varanus rudicollis). Subjects were trained to discriminate between black and white stimuli. Both subjects learned an initial discrimination task as well as two reversals, with the second reversal requiring fewer sessions than the first. This reduction in trials required for reversal acquisition provides evidence for behavioral flexibility in the monitor lizard genus. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

The discrimination of natural movement by budgerigars (Melopsittacus undulates) and pigeons (Columba livia).

Three experiments examined the ability of birds to discriminate between the actions of walking forwards and backwards as demonstrated by video clips of a human walking a dog. Experiment 1 revealed that budgerigars (Melopsittacus undulates) could discriminate between these actions when the demonstrators moved consistently from left to right. Test trials then revealed that the discrimination transferred, without additional training, to clips of the demonstrators moving from right to left. Experiment 2 replicated the findings from Experiment 1 except that the demonstrators walked as if on a treadmill in the center of the display screen. The results from the first 2 experiments were replicated with pigeons in Experiment 3. The results cannot be explained if it is assumed that animals rely on static cues, such as those derived from individual postures, in order to discriminate between the actions of another animal. Instead, this type of discrimination appears to be controlled by dynamic cues derived from changes in the posture of the demonstrators. (PsycINFO Database Record (c) 2010 APA, all rights reserved)