Ultrasonic vocalizations by male house mice (Mus musculus) to novel odors: roles of infant and adult experience

Two experiments were conducted to examine 70-kHz ultrasonic courtship vocalizations by adult male mice (Mus musculus) to novel odors following exposure to these odors in infancy and/or adulthood. The research was performed in hopes of better understanding the experiences giving rise to vocalizations to naturally occurring chemosignals. Experiment 1 demonstrated that adult males normally do not vocalize to the urine of female rats but would come to do so if adult female mice odorized with female rat urine were repeatedly encountered postpubertally. On the other hand, encountering their own mother odorized with female rat urine from birth until weaning did not promote vocalizations to the urine of female rats. Experiment 2 was designed to examine vocalizations to the urine of female mice whose urinary odor was altered by the ingestion of fenugreek, a spice. Although the magnitude of the effect was smaller in this experiment, greater amounts of vocalization again were seen by males that as adults encountered females that had ingested fenugreek. Males with such experience also showed a small but significant elevation in vocalizations to the fenugreek odor itself. Again, experience with the novel odor during infancy was not associated with elevated vocalizations during adulthood either to fenugreek-altered urine or to the fenugreek odor itself. Thus vocalizations to two different novel odors occurred only after an adult male had encountered an adult female odorized with the novel odor. On the other hand, none of the novel odor experiences eliminated vocalizations to the naturally occurring chemosignal in female mouse urine.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effects of early exposure to ventral gland odor on physical and behavioral development and adult social behavior in Mongolian gerbils.

Comparisons were made between male and female gerbils reared by ventral gland-excised and intact patents. Repeated measurements before and after puberty failed to reveal an effect of gland odor exposure on body weight, ventral gland size, open-field defecation, and time of vaginal opening. Exposed animals were more attracted than nonexposed animals to a strange male's gland odor during preference tests involving "marked" and "unmarked" paper strips. Opposite-sex pairs of exposed animals engaged in more social behavior than did nonexposed pairs, but there was no difference in fighting frequency or, during extended cohabiitation, in fecundity. While early exposure to gland odor apparently does not affect physical maturation, it may enhance later responsiveness to stimuli (gland odors) that are useful in locating conspecifics and that facilitate social interactions between previously unacquainted gerbils.     

Development of responsiveness to conspecific scent in house mice: effects of preweaning and postweaning experiences

Responses to male conspecific odors (soiled bedding) presented in an alleyway were compared among five groups of adult male albino house mice with different rearing histories. Both isolated mice that had as pups been fostered onto a rat mother and normally nursed mice that had been group housed since weaning showed reduced attraction to conspecific odor. Preweaning paternal presence, a factor known to affect the development of response to male conspecific scent in rats and gerbils, had no reliable effect with mice.     

Recognition of odors and identification of sources

The purpose of the present study was to investigate the accuracy of the memory for odors and for the location of odors. In Experiment 1, 5 unfamiliar odors were presented in each of 2 rooms. Twenty participants were instructed to remember only the odors (odor-only control group) and 20 were instructed to remember both the odors and the room where the odors were presented (odor place group). In Experiment 2, both the odor presentation room and the sex of the experimenters were manipulated to increase the uniqueness of the odor location. The results demonstrated that the memory for an odor is superior to the memory for the location of an odor. The results also indicated that the intention to learn the sources of an odor improves the memory for the source. These results are discussed in the context of the source monitoring framework.     

Responses of dominant and subordinate male rats to the odors of male and female conspecifics

The resident-intruder paradigm was used to examine the effects of social dominance and individual recognition on odor preferences and urine-marking in male rats. Resident males were significantly more aggressive than intruders and spent more time investigating the odors of familiar intruders. Resident males urine-marked most over the odors of females and familiar intruders while intruders marked least over the odor of the familiar resident. Intruders did not avoid investigating nor marking over the odors of familiar resident males or other conspecifics. These results suggest that individual odors of male rats may be more salient than a general odor of dominance, and that the dominant males increase their investigation and marking over the odors of familiar subordinates but not unfamiliar subordinates. The importance of olfactory learning during aggressive interactions is discussed.     

Sensory cues that elicit ultrasonic vocalizations in female rats (Rattus norvegicus)

Female rats emit ultrasonic vocalizations during copulation. Female vocalizations are associated with darting and other proceptive behavior. In addition, females frequently call while approaching the male. A series of experiments was undertaken to determine whether female rats emit ultrasonic vocalizations in response to other rats or to their odors. Females were exposed either to bedding soiled by males or females or to devocalized conspecifics separated from the subject by a barrier. Females vocalized more to male cues than to female cues, regardless of whether the odor cues were from soiled bedding or from a devocalized conspecific. In addition, subjects vocalized more when presented with a devocalized female rather than a neutral stimulus. Furthermore, devocalized adult males, separated by a barrier, were more effective than either devocalized castrated or juvenile males in eliciting vocalizations; in turn, castrates and juveniles were more effective than neutral stimuli. Female calling was likely induced by odors from the male. In one experiment, the female subject was positioned in such a way that she could neither see or touch the stimulus male. Presentation of tape-recorded male vocalizations did not affect calling by the female. Vocalizations emitted by females in response to male odors may attract males or may facilitate subsequent copulatory behavior by the male.     

Perceptual learning with odors: implications for psychological accounts of odor quality perception

After two odors have been experienced in a mixture, the pair are subsequently rated as sharing more qualities and smelling more alike than equally exposed controls. These effects may result from the retrieval of a common mixture memory when either component is sniffed alone. If correct, odor pairs experienced together in a mixture should also be less discriminable than those experienced an equal number of times but in different mixtures. This was tested here by exposing participants to two odor mixtures (either AX, BY or AY, BX) and then testing their ability to discriminate between the components. As predicted, odors previously experienced together as a mixture were less discriminable than controls. These and related findings noted above suggest that learning and memory play an important role in odor quality perception.     

Similarity in the qualities of individual odors among kin and species in Turkish (Mesocricetus brandti) and golden (Mesocricetus auratus) hamsters.

In this investigation, the authors used habituation techniques to explore similarities and differences in the qualities of individual odors from hamsters. In Experiment 1, male Turkish hamsters (Mesocricetus brandti) treated flank-gland odors of 2 males from 1 litter as similar compared with the odor of a male from another litter, whether the odor donors were familiar or unfamiliar. At the same time, the Turkish hamsters discriminated between the subtle differences in the individual odors of their familiar brothers. In Experiment 2, male Turkish and golden hamsters (Mesocricetus auratus) treated the flank-gland odors of 2 unfamiliar, unrelated conspecifics as similar compared with the flank odor of a heterospecific individual. The results suggest that similarities in individual odors are related to genetic similarity of the odor donors. These similarities could provide a basis for different types of social recognition, including kin and species recognition.     

Effects of social isolation in adulthood on odor preferences and urine-marking in male rats

Male rats isolated for 60 days in adulthood spent less time investigating odors of females and urine-marked less over these odors than did males kept in groups of three. Isolated males did not differ from grouped males in their responses to odors of unfamiliar males or their own odors. After social experience the isolated males showed an increase in urine-marking but no change in odor preferences. Individual housing therefore appears to alter olfactory communication in the same way that it does other social behaviors and these changes may be mediated by the same mechanisms.     

Very short term recognition memory for odors

An investigation of very short term olfactory recognition memory was made with odors of low familiarity to subjects. The experimental procedure was that currently used to make qualitative similarity judgments on odors delivered in paired succession. Subjects made similarity judgments in a yes/no recognition paradigm on odors that were either identical or different. The dependence of recognition performance upon the degree of qualitative similarity was assessed by using two sets of dissimilar odor pairs: slightly dissimilar pairs (S1) and very dissimilar pairs (S2). Performance in terms of correct judgments (hits, correct rejections) was rather good for identical pairs in both sets and was nearly perfect for very dissimilar pairs with a delay of 2–300 sec, suggesting no effect of time or similarity on performance. However, for slightly dissimilar pairs, false alarms increased in number, thereby indicating a dependence of the recognition score on the qualitative distance between odors. In addition, false alarms tended to increase with the lengthening of the retention interval. It was suggested that the subjects based their responses on their capability to detect differences between odors rather than recognizing their similarities. Correct identifications were thus preserved at the cost of increasing false alarms when the discrimination task was made more difficult by closer similarity between odors (S1) or by the fading of memory traces with time. Studying the congruence between the similarity judgments and the kind of evocations associated with paired odors gives some support to the view that recognition performances had some cognitive/semantic basis.     

Olfaction,Emotion and Associative Learning: Effects on Motivated Behavior

Two experiments were conducted to investigate emotional associative learning to odors and subsequent behavioral effects. In Experiment 1, participants experienced a frustration mood induction in the presence of an unfamiliar ambient odor and later worked on puzzle tests in a room scented with either the same-odor, a different-odor, or no-odor. Participants in the same-odor condition spent significantly less time working on the tests than participants in the other conditions; however, test accuracy did not vary. To clarify the findings, Experiment 2 included a test-only control and an emotionally neutral same-odor conditions. Results were compatible with the conclusion that decreased time spent by participants in the negative-same-odor condition was due to emotions elicited by associative learning to the ambient odor, although alternative interpretations remain possible. These data extend our previous results with children and suggest that odors readily become associated to emotions and can thereby influence behavior.     

Recollective experience in odor recognition: Influences of adult age and familiarity

We examined recollective experience in odor memory as a function of age, intention to learn, and familiarity. Young and older adults studied a set of familiar and unfamiliar odors with incidental or intentional encoding instructions. At recognition, participants indicated whether their response was based on explicit recollection (remembering), a feeling of familiarity (knowing), or guessing. The results indicated no age-related differences in the distribution of experiential responses for unfamiliar odors. By contrast, for familiar odors the young demonstrated more explicit recollection than the older adults, who produced more know and guess responses. Intention to learn was unrelated to recollective experience. In addition, the observed age differences in remember responses for familiar odors were eliminated when odor naming was statistically controlled. This suggests that age-related deficits in activating specific odor knowledge (i.e., odor names) play an important role for age differences in recollective experience of olfactory information.     

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).     

Gender differences in preadolescent children's online interactions: Symbolic modes of self-presentation and self-expression

Preadolescent children who did not know one another interacted in a multiuser domain (MUD), an online site designed to facilitate identity exploration and peer interaction. Each child participated in two separate sessions, one with a same-sex and one with an opposite-sex peer. Children created characters that reflected real-life properties of themselves, such as gender and interests in popular culture. Boys in same-sex pairs interacted with one another through action, rapid changes, and playful exchanges. Girls in same-sex pairs interacted primarily through written dialogue. In mixed pairs, boys wrote more and engaged in less playful exchanges, and girls wrote fewer and increased their actions. The results suggest that boys and girls have their own unique play styles with same-sex peers, but will moderate those patterns during late childhood to communicate with peers of the opposite sex.     

Very long-term memory for odors: retention of odor-name associations.

The ability to remember odor-name associations for recent odors (those associated with everyday products experienced within the past 2 years) and distant odors (those associated with children's toys not encountered for 3 years or more) was examined in two experiments. In recognition tasks, subjects attempted to match odor names to odors, or odors to odor names. In a recall task, subjects tried to identify odors by name. The results showed that although odor retention was better for recent than distant odors, significant retention remains for odors not experienced since childhood. These results are consistent with other studies that found very slow and gradual loss of odor information in memory. They extend that research by showing that odor information is still available over a much longer period of time.     

Male hamster preference for odors of female hamster vaginal discharges: studies of experiential and hormonal determinants.

Male hamsters approach sources of odors from female hamster vaginal discharges and spend significantly more time around these odor sources than around control locations in the test box. This preference for female hamster vaginal odors appears in sexually inexperienced as well as experienced males, even in individuals isolated from females since the time of weaning. Castration significantly reduces the sex odor preference, and treatment with testosterone propionate partially restores it.     

Pheromone‐mediated intrasexual aggression in male lizards,Podarcis hispanicus

Sex recognition is based on color signals in many species of lizards. However, olfactory stimuli are also clearly involved, and many species might rely primarily on chemoreception. We aimed to examine whether color pattern or odors, or a combination of both factors, induce the aggressive response of males of the lizard P. hispanicus. We experimentally manipulated the coloration and odor of male P. hispanicus, thereby creating groups with all combinations between coloration and odor of males or females. Using data from staged encounters, we compared the responses of resident males to the experimental groups of manipulated males and their response to unmanipulated individuals (males and females). Responding males reacted significantly more aggressively to intruders with male odors independent of their coloration, whereas intruders with female odors did not elicit aggressive responses but were preferentially courted, irrespective of their actual sex and body coloration. In addition, intruders with female odors elicited a higher number of tongue‐flick explorations than male odor ones. Comparisons with unmanipulated male and female intruders agreed with these expectations. Therefore, at least at close range, odoriferous cues seem to be more important than color patterns in sex recognition and intrasexual aggression by male P. hispanicus. We suggest that this might be a pattern commoner than expected in many species of reptiles.Aggr. Behav. 28:154–163, 2002. © 2002 Wiley‐Liss, Inc.     

Odor from rats tasting a signal of illness

Rats running in a runway emit discriminable odors when encountering reward (R) or nonreward (N) goal events, and subsequent rats use these odors as discriminative stimuli to alter their approach speeds. In the present studies, a third goal event, aversively conditioned denatonium saccharide (A), was introduced. In Experiment 1, rats evidently emitted an odor when encountering the A goal event, because in the presence of this A odor subsequent conspecifics slowed their approach to the goal, much like their behavior on N trials. In Experiment 2, when N odor signaled R goal events and A odor signaled A goal events, rats approached quickly to N but slowly to A, indicating that they could discriminate N and A odors at the given concentrations. These studies indicate that rats emit an odor when confronted with a signal of impending illness and that this odor seems readily discriminable from R and N odors.     

Effect of postweaning social experience on response of Siberian hamsters (Phodopus sungorus sungorus) toward young

Between 18 and 50 days of age, Siberian hamsters were housed either with same-sex littermates, opposite-sex littermates, opposite-sex littermates and parents, or opposite-sex littermates, parents, and a younger litter. When adults, these animals were presented with two 3-8-day-old pups for 8 hr, and their responses were recorded. Rearing conditions did not affect behavior of females. Males housed with female littermates in the absence of a younger litter showed fewer pup attacks and more nesting with pups than did males housed only with other males. Thus, housing with females in the early postweaning period may influence males' later (adult) responses toward pups. Only among hamsters housed with same-sex littermates did males and females differ in their response to pups, a result emphasizing that sex differences in behavior may depend on early social rearing.