Spatial behavior in gerbils (Meriones unguiculatus).

Investigated whether adult gerbils could use an allocentric frame of reference to efficiently solve a spatial memory task. 38 male Ss were allowed to explore an arena containing an object. The external reference frame was reduced to a single visual landmark. After habituation, Ss entered the arena from a new direction. A 2nd object, identical to the 1st object, was placed symmetrically with regard to the landmark. The 2nd object was explored more than the 1st object, a result showing that the 2nd object was differentiated on the basis of location. This result suggests that, during the course of exploration, Ss had learned about the spatial features of the experimental situation. It is suggested that Ss' final discrimination performance (preference for the novel stimulus location) reflected an allocentric rather than egocentric frame of reference. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Conditioned social aversion in the male Mongolian gerbil (Meriones unguiculatus).

Adult male Mongolian gerbils formed conditioned social aversions to young male conspecifics. The basic paradigm consisted of pairing an S with a young animal (test stimulus) for 5 min and then injecting the S with LiCl to produce gastrointestinal distress. When retested 48 hrs later, the S avoided the test stimulus, as indicated by significantly decreased investigation time and approach frequency. Through a series of 5 experiments with 290 Ss on dose level, delay of toxin injection, and stimulus generalization, it was demonstrated that a dose of .03 ml/g of .15 M LiCl was effective, the toxin should be given within 15 min of the preliminary social pairing, the social aversion was specific to the particular first paired stimulus animal, and isolation between test sessions was necessary for an aversion to develop. This paradigm extends knowledge of the learned aversion process and demonstrates that this type of learning can be generalized to a social situation by gerbils. (36 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Directional responses to sounds in young gerbils (Meriones unguiculatus).

Conducted 3 experiments to determine the ability of infant gerbils to approach an auditory stimulus. In Exp I, 48 16–23 day old Ss were tested in a circular apparatus with a central start area and a movable sound source located at 1 of 8 positions around the perimeter. Stimuli included high- and low-intensity presentations of a tape-recorded gerbil social call, a broad-band white noise stimulus, and a no-stimulus control condition. Ss showed a strong tendency to approach the low-intensity social call and a less pronounced tendency to approach the white noise. In Exp II, 24 16–23 day old Ss were tested in the same apparatus with or without ear blocks to determine the role of binaural cues in directional approach responding. The tendency to approach a low-intensity vocalization was disrupted by obstruction of one ear but not by blocking both ears. Thus, binaural balance was shown to be important for early sound localization. In Exp III, using 6 12–27 day old Ss, the tendency to approach a social call was compared at 12–25, 16–29, 20–23, and 24–27 days after birth. Approach responses were first seen at 16–29 days of age. The responses continued at 20–23 days of age but began to wane at 24–27 days of age. (33 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Effects of olfactory bulb ablation and androgen on marking and agonistic behavior in male Mongolian gerbils (Meriones unguiculatus).

Male Mongolian gerbils, selected for high marking frequency, were paired with male opponents, and marking and fighting behavior were recorded. Animals then underwent castration, bilateral bulbectomy, unilateral bulbectomy, the combined operations, or a sham operation; and their behavior was again observed. All operated animals showed drastic reduction in both marking and aggressive encounters. Injections of testosterone propionate (TP) produced complete restoration of marking in castrates, but not in bilaterally or unilaterally bulbectomized animals or combined operates. The exhibition of aggression after injections of TP, however, was enhanced to supernormal levels in bulbectomized or bulbectomized-castrated animals. The results suggest the following: that removal of the olfactory bulbs may eliminate a critical neural input necessary for the normal expression of marking and agonistic behavior; that although marking and fighting are influenced by olfactory input and gonadal steroids, their regulatory mechanisms may not be identical; and that removal of the bulbs may sensitize a neural mechanism controlling aggression, thus potentiating its elicitation following administration of exogenous androgen. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Depth perception in Mongolian gerbils (Meriones unguiculatus) and spiny mice (Acomys russatus and A. cahirinus).

Studied depth perception in gerbils and spiny mice with a modified visual cliff that varied the height of a platform from 5.08 to 25.4 cm and presented Ss with an apparent drop-off to a patterned or a white field. Ss were 6 8–22 mo old female gerbils and 12 7–28 mo old spiny mice. Time to descend from the platform and orienting response frequency were recorded. For gerbils, neither measure varied significantly between the platforms. Both mice species increased descent time and orienting response frequency as platform height increased. Results suggest that both gerbils and spiny mice perceived depth, though there appeared to be a difference between the species' use of sensory cues in descending from a visual cliff. The spiny mice appeared to rely more on visual cues than did the gerbils. Data also reveal subtle behavioral differences between the mice species that may relate to their successful sympatry. Results are discussed by alluding to ecological differences between these species in their natural habitats. (24 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Kinship and familiarity as factors affecting social transfer of food preferences in adult Mongolian gerbils (Meriones unguiculatus).

Experiments were carried out with Mongolian gerbils (Meriones unguiculatus) to assess whether a socially mediated acquisition of diet selection exists in this species. Results showed that a gerbil was influenced in its diet choices by information extracted during a brief period of interaction with a familiar conspecific that had recently eaten a novel food. Data revealed that the acquisition of a food preference from a conspecific depends on the existence of a social bond between the interacting gerbils. Either genetic relatedness (being brother or sister raised in different litters) or familiarity (being bred in the same litter or being member of a reproductive pair) is necessary for the transfer of information. Unfamiliar and unrelated observer gerbils did not selectively choose their demonstrator's food. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Pavlovian conditioning of social affirmative behavior in the Mongolian gerbil (Meriones unguiculatus).

Gerbils learned to approach a spatial-olfactory stimulus that signaled access to their pairmate. Experiments 1 and 3 used a discrimination procedure in which 1 conditioned stimulus (the CS+) was presented immediately before access to the pairmate and another (the CS–) was presented alone. Both male and female gerbils came to approach the CS+ sooner than the CS– and spent more time near the CS + than the CS–. Discrimination learning was facilitated by making the CS+ and CS– spatially distinct (Experiment 3). Learning also was demonstrated in male gerbils, using a between-subjects design with a single CS. Pairing the CS with the opportunity for social interaction resulted in greater approach to the CS within 10 trials than presenting the CS and social opportunity in an unpaired fashion (Experiment 2). These findings demonstrate social-affiliative learning in the Mongolian gerbil. Similarities and differences between these findings and sexual conditioning effects in other species are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Some experimental tests of the functional significance of scent-marking by gerbils (Meriones unguiculatus).

Investigated the functional significance of male gerbil scent-marks in 4 experiments with 60 male and female Mongolian gerbils. In Exps I and II, males in a novel test environment marked more, groomed more, and urinated less in the presence of odors of a strange male than in their absence. Female odors elicited male marking more than did male odors. In Exps III and IV, females were selectively less aggressive toward familiar-smelling males in comparison with unfamiliar-smelling males. These results, in conjunction with field observations of related species, call into question the hypothesis that gerbil scent-marks function territorially and instead suggest that the primary targets are adult females. (34 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

How do Mongolian gerbils (Meriones unguiculatus) pass the time? Adjunctive behavior during temporal differentiation in gerbils.

Mongolian gerbils (Meriones unguiculatus) received training on a temporal differentiation task, where reinforcement was contingent on remaining on a small platform for more than t, and t was varied over a range from 2 to 15 s. Adjunctive behaviors during platform residence were also observed. Mean time of residence on the platform almost exactly matched the time requirement, and coefficients of variation of residence times remained constant at times above 2 s, in accordance with scalar timing. The rate of adjunctive behaviors varied linearly with reinforcement rate, as predicted by the behavioral theory of timing (BeT; P R. Killeen & G. J. Fetterman, 1988). The number of adjunctive behaviors per platform response and the nature of adjunctive sequences were both, however, less consistent with BeT predictions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Organization of escape movements from overhead threats in the Mongolian gerbil (Meriones unguiculatus).

Mongolian gerbils were presented with overhead visual stimuli in different environmental situations. The organization of escape movements was investigated with video-based image analysis methods. In Exp 1, gerbils in an open field established a home base and organized their escape trajectories with reference to both the home base and the location of the stimulus. In Exp 2, gerbils were provided pairs of refuges. They used these refuges as home bases and organized their responses with reference to the home base. In Exp 3, pairs of gerbils were tested in a field with refuges. Gerbils organized their escape movements with reference to their distance to the home base in relation to the distance of the other member of the pair to the home base. The results of these experiments suggest that escape movements in gerbils can be characterized as orienting to safety rather than to fleeing from risk. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Socially induced delayed reproduction in female Mongolian gerbils (Meriones unguiculatus): Is there anything special about dominant females?

In 4 experiments, the authors explored effects of interaction with both sexually active adult female and unfamiliar adult male Mongolian gerbils (Meriones unguiculatus) on young female gerbils' ages at first parturition. Presence of a natural mother retarded development of her daughters. However, presence of a natural mother had no greater effect on her daughters' development than did presence of any other familiar animal, either male or female. Further, exposing young female gerbils to an unfamiliar male accelerated their development even when their reproductively active mothers were present. The data indicate that maintaining young female gerbils in stable family groups results in both inhibition of sexual maturation (caused by exposure to familiar individuals) and failure to activate sexual development (caused by lack of exposure to unfamiliar males). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Sound localization and use of binaural cues by the gerbil (Meriones unguiculatus).

Noise-localization thresholds and the ability to localize pure tones at 60° separation were determined for gerbils. The gerbils were trained using a two-choice procedure with observing response in which the gerbils made a left or right response to sounds emanating from their left or right side in order to obtain food. The average 75% correct localization threshold of 5 gerbils for a 100-ms noise burst was 27° with chance performance (p?>?.01) reached at 12°. The ability of 4 gerbils to localize both low- and high-frequency pure tones indicates that gerbils are able to use both phase- and intensity-difference locus cues. The frequency at which tone localization was poorest was 2.8 kHz, well below the theoretical frequency of ambiguity of the phase cue but within the frequency range at which phase locking declines in the mammalian auditory system. The sound localization ability of gerbils is typical of small rodents, and there is no obvious sign that it is affected by the degenerative disorder of the central auditory system which has been recently discovered in gerbils. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ventral scent marking in Meriones unguiculatus may contribute to thermoregulation.

Conducted 3 experiments with adult male gerbils to demonstrate that ventral scent marking can act to transfer body heat to the object marked. Exp I, with 16 Ss, showed that surgical removal of the ventral gland pad in 8 Ss reduced the amount of heat transferred by 50%, even though intact and glandless Ss did not differ in the average frequency of scent marking. Exp II, with the same 16 Ss used in Exp I, demonstrated that the difference in heat transfer due to the presence or absence of the scent pad was not due to differential pressure applied to the substrate during marking. Exp III, with 14 Ss, showed that the pattern of ventral hair spread that occurred as an S moved over an object was different between intact and glandless Ss but that this difference did not account for the difference in heat transfer. It is suggested that heat transfer to the environment with ventral scent marking may increase thermoregulatory competence and also may function to volatilize sebum used in chemocommunication. (15 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Foraging experience affects gerbils' (Meriones unguiculatus) radial arm maze performance.

Tested D. S. Olton's (1978) hypothesis that the gerbil's ability to easily learn the radial maze task is due to a natural "win-shift" foraging strategy, a tendency to avoid recently visited food sites. 25 Mongolian gerbils at weaning were put in 1 of 2 environments—one in which the source of food and water was always located in the same place and the other in which the source changed location from day to day—until they were 60 days of age. They then were tested in a 17-arm radial maze. Ss reared in the environment with variable locations of food and water learned the maze task more quickly than Ss reared in the other environment. Results are consistent with Olton's hypothesis. (10 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Harderian gland exudates in the male Meriones unguiculatus regulate female proceptive behavior, aggression, and investigation.

Replicated an earlier finding by the present authors (see record 1986-08500-001) that female proceptive behaviors toward Harderianectomized males are diminished. In the present study, it was shown that estrous females directed fewer proceptive acts toward males lacking Harderian glands. In addition, it was found that females were more defensively aggressive toward Harderianectomized males and preferred to spend more time in the vicinity of intact males. It is speculated that Harderian spread allows the female to assess the reproductive competence of the male. (8 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ultrasonic signaling in the gerbil (Meriones unguiculatus): Social interaction and olfaction.

Conducted 3 experiments with 53 gerbils to assess the conditions for ultrasonic emission. Exp I indicates that isolated Ss rarely emitted ultrasounds, males emitted at a higher rate than females, and emission rates ordinarily decreased with continual testing. Ultrasonic emissions were stimulated by olfactory cues from conspecifics. Exp II demonstrates that dominant males emitted more ultrasounds than subordinate males and responded to cues from anesthetized, shaved, or dead animals or from anesthetized animals in the dark. Exp III shows that body hair elicited ultrasounds from males unless organic materials were removed from the hair with chloroform. Hair was an effective stimulus at a distance only when an airstream blew the volatiles over the recipient. (31 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Learning and male–male sexual competition in Japanese quail (Coturnix japonica).

Male Japanese quail (Coturnix japonica) were trained individually to discriminate between 2 sounds presented at opposite ends of an outdoor aviary. One of the sounds (the positive conditioned stimulus [CS+]) was associated with the release of a female, and the other (the negative CS [CS–]) was presented alone. Which of the 2 sounds served as the CS+ (and which served as the CS–) was counterbalanced across Ss. The Ss came to approach their CS+ but did not move away from their CS–. After having been conditioned individually, the subjects were tested in pairs, with a single female released after the presentation of a stimulus that was the CS+ for one of the males and the CS– for the other male. During most of these tests, the male for whom the prefemale stimulus was the CS+ copulated with the female before the male for whom the prefemale stimulus was the CS–. These results indicate that learning can have an important role in competition for access to a reproductive partner. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Olfactory conditioning of sexual behavior in the male rat (Rattus norvegicus).

The role of classical conditioning in the copulatory preferences of male Long-Evans rats (Rattus norvegicus) was examined by pairing a neutral olfactory stimulus (almond odor) with female reproductive status. During training trials, the males were given access to scented or unscented females that were either sexually receptive or unreceptive. Subsequently, copulatory preferences were tested in males given simultaneous access to 2 receptive females, 1 scented and 1 not. Males trained with scented-receptive females displayed an ejaculatory preference for the scented female. Males trained with scented-unreceptive females or with unscented-receptive females displayed an ejaculatory preference for the unscented female. Males displayed no preference when scent and reproductive status were paired randomly. These results demonstrate that classical conditioning produces an ejaculatory preference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Medial preoptic lesions disrupt parental behavior in both male and female California mice (Peromyscus californicus).

California mice (Peromyscus californicus) are monogamous and naturally biparental, making them an ideal species in which to study the neural basis of paternal behavior. A male or female from each male-female pair was given an electrolytic or sham lesion in the medial preoptic area (MPOA), an area known to be critical for the expression of maternal behavior in rats, and retested for parental responsiveness. MPOA-lesioned males and females showed significantly longer latencies to show parental behavior and spent significantly less time near pups, sniffing pups, and licking pups than sham-lesioned mice. However, MPOA lesions did not reduce time spent hovering over pups. The results suggest that the neural mechanisms mediating paternal behavior are similar to those mediating maternal behavior in this species. (PsycINFO Database Record (c) 2010 APA, all rights reserved)