Vocalization Rate Research Articles

Early postnatal behavioral changes in the Mecp2‐308 truncation mouse model of Rett syndrome

In a mouse model of Rett syndrome (RTT) which expresses a truncated form of methyl-CpG-binding protein 2 (Mecp2) gene (Mecp2-308), we performed a neurobehavioral evaluation across the life span, starting from soon after birth till adulthood. A focus was made on those developmental phases and behavioral domains which have not been previously investigated. The results evidenced subtle anomalies on postnatal days (pnds) 3 to 9 (so-called presymptomatic phase) in spontaneous movements by hemizygous neonatal male mice. Specifically as early as pnd 3, mutant pups exhibited more intense curling and more side responses and on pnd 9 more pivoting and head rising behaviors than wild type (wt) littermates. A significant decrease in ultrasonic vocalization rate, also emerged in Mecp2-308 pups. The same mice were also characterized by increased anxiety-like behaviors (open-field and zero-maze tests) during the early symptomatic phase, in the absence of changes in cognitive passive-avoidance task and rotarod performances. Upon the clearly symptomatic stage, 5-month-old Mecp2-308 mice were also associated with reduced spontaneous home-cage motor activity, motor coordination impairments (rotarod and dowel tests), and a more marked profile of D-amphetamine (10 mg/kg) released stereotyped behavioral syndrome than wt mice. Present results provide an interesting timeline of the progression of symptoms in the Mecp2-308 model and emphasize the need for increased attention to the presymptomatic phase which may be especially informative in mouse models of human neurodevelopmental disorders. This analysis has provided evidence of precocious behavioral markers of RTT and has identified an early developmental window of opportunities on which potential therapies could be investigated.

Behavioral and physiological responses of nestling pied flycatchers to acoustic stress

The extended secretion of stress hormones in fully developed animals is known to have profound consequences. However, little is known about the effects of stress on the behavior and physiology of free-living young animals, and how such responses relate to each other. We repeatedly (during 5 consecutive days, 1 h/day) exposed the nestlings of a passerine bird, the pied flycatcher ( Ficedula hypoleuca), to recordings of nestling distress calls and examined their behavioral and physiological responses to the stressor on the first and the last day of the experiment (on days 9 and 13 post-hatch, respectively). In comparison with control siblings, stressed nestlings reduced the amount of time that they devoted to vocalization and locomotion and increased levels of circulating corticosterone. In 9-day-old nestlings, the level of stress-induced hormone was negatively related to locomotor activity, but not to the rate of vocalizations. The repeated presentation of the stressor increased the heterophile-to-lymphocyte ratio in nestlings but did not affect nestling growth rate. In 13-day-old nestlings, the level of stress-induced corticosterone was not related to behavioral activity. These results suggest that the high level of corticosterone released by immature nestlings in response to a stressor may promote anti-predator behavior (e.g., passive avoidance behavior). Moreover, repeatedly induced stress may have a cumulative and potentially negative effect on individual physiology.

Bird population density estimated from acoustic signals

Summary1.Many animal species are detected primarily by sound. Although songs, calls and other sounds are often used for population assessment, as in bird point counts and hydrophone surveys of cetaceans, there are few rigorous methods for estimating population density from acoustic data.2.The problem has several parts – distinguishing individuals, adjusting for individuals that are missed, and adjusting for the area sampled. Spatially explicit capture–recapture (SECR) is a statistical methodology that addresses jointly the second and third parts of the problem. We have extended SECR to use uncalibrated information from acoustic signals on the distance to each source.3.We applied this extension of SECR to data from an acoustic survey of ovenbirdSeiurus aurocapilladensity in an eastern US deciduous forest with multiple four‐microphone arrays. We modelled average power from spectrograms of ovenbird songs measured within a window of 0·7 s duration and frequencies between 4200 and 5200 Hz.4.The resulting estimates of the density of singing males (0·19 ha−1SE 0·03 ha−1) were consistent with estimates of the adult male population density from mist‐netting (0·36 ha−1SE 0·12 ha−1). The fitted model predicts sound attenuation of 0·11 dB m−1(SE 0·01 dB m−1) in excess of losses from spherical spreading.5.Synthesis and applications.Our method for estimating animal population density from acoustic signals fills a gap in the census methods available for visually cryptic but vocal taxa, including many species of bird and cetacean. The necessary equipment is simple and readily available; as few as two microphones may provide adequate estimates, given spatial replication. The method requires that individuals detected at the same place are acoustically distinguishable and all individuals vocalize during the recording interval, or that theper capitarate of vocalization is known. We believe these requirements can be met, with suitable field methods, for a significant number of songbird species.

Sex differences in vocal patterns in the northern muriqui (Brachyteles hypoxanthus)

We investigated whether sex differences in spatial dynamics correlate with rates of staccato and neigh vocalizations in northern muriquis (Brachyteles hypoxanthus) at the Reserva Particular do Patrimônio Natural-Feliciano Miguel Abdala, Minas Gerais, Brazil. A total of 2,727 10 min focal subject samples were collected on 32 adult females and 31 adult males between April 2007 and March 2008. Compared with males, females spent a significantly lower proportion of their time in proximity to other group members and gave staccatos at significantly higher rates while feeding, resting, and traveling. Conversely, males emitted neigh vocalizations at significantly higher rates than females when feeding and resting only. Both sexes gave significantly more staccatos when feeding than when they were engaged in other activities, but their respective rates of neighs did not vary across activities. Both females and males emitted staccato vocalizations at significantly higher rates during times of the year when preferred foods were scarce, but no seasonal differences in the rates of neigh vocalizations were observed in either sex. Females and males showed a reduction in the number of neighbors following staccato vocalizations and an increase in the number of neighbors following neigh vocalizations. Our findings of sex differences in the rates of staccato and neigh vocalizations and the effects of these vocalizations on interindividual spacing are consistent with sex differences in spatial dynamics, and confirm the role of vocal communication in mediating spatial associations in this species.

Estimating Abundance From One‐Dimensional Passive Acoustic Surveys

ABSTRACT Conventional distance sampling, the most‐used method of estimating animal density and abundance, requires ranges to detected individuals, which are not easily measured for vocalizations. However, in some circumstances the sequential pattern of detection of vocalizations along a transect line gives information about the range of detection. Thus, from a one‐dimensional acoustic point‐transect survey (i.e., records of vocalizations detected or not detected at regularly spaced listening stations) it is possible to obtain a useful estimate of density or abundance. I developed equations for estimation of density for one‐dimensional surveys. Using simulations I found that for the method to have little bias when both range of detection and rate of vocalization need to be estimated, stations needed to be spaced at 30–80% of the range of detection and the rate of vocalization should be >0.7. If either the range of detection or rate of vocalization is known, conditions are relaxed, and when both parameters are known the method works well almost universally. In favorable conditions for one‐dimensional methods, estimated abundances have overall errors not much larger than those from conventional line‐transect distance sampling. The methods appeared useful when applied to real acoustic data from whale surveys. The techniques may also be useful in surveys with nonacoustic detection of animals.

PRX-00023, a selective serotonin 1A receptor agonist, reduces ultrasonic vocalizations in infant rats bred for high infantile anxiety

To address the development of early anxiety disorders across the lifespan, the High USV line of rats was bred based on rates of infant ultrasonic vocalization in the 40–50 kHz range of predominant frequencies (USV) to maternal separation at postnatal day (P) 10. In this study, rates of USV in High line infants (pups: Postnatal Day 11 ± 1) were compared to those of randomly-bred controls in response to EPIX compound PRX-00023, a unique serotonin (5-HT) agonist, acting exclusively at the 5-HT1A receptor, or buspirone, a nonspecific 5HT1A agonist. After testing, pups were examined for sedation and other drug-related effects. The results indicated that all doses of buspirone reduced USV rates in isolation, consistent with other reports. PRX-00023 significantly reduced USV rates at the lowest doses (0.01–0.05 mg/kg). None of the PRX-00023 doses produced sedation, whereas all but the lowest dose of buspirone (0.1 mg/kg) produced sedation effects. The results suggest that this compound alleviates infantile anxiety-like behavior with great specificity in rats bred for high anxiety/depressive phenotypes by selectively targeting 5-HT1A receptors, possibly by both pre- and post-synaptic mechanisms.

Antidepressant efficacy screening of novel targets in the chick anxiety-depression model

The chick anxiety-depression model is a hybrid simulation, which may prove useful as an early preclinical dual pharmacological screen for novel therapeutics. Separate dose-response studies were conducted with seven test compounds that have screened positive for antidepressant effects in rodent depression models and included prasterone (5.0-40.0 mg/kg), memantine (2.5-20.0 mg/kg), ketamine (1.0-10.0 mg/kg), mifepristone (50.0-400.0 mg/kg), DOV216,303 (5.0-20.0 mg/kg), CGP36742 (2.5-15.0 mg/kg), and antalarmin (1.0-30.0 mg/kg). Chicks aged 4-6 days posthatch received test compounds intramuscularly 15 min before social separation, in which distress vocalization rates were recorded. High rates of vocalization in the first phase (0-5 min) of social separation seem to model an anxiety-like state and lower rates of vocalization in the second phase (30-60 min) seem to model a depression-like state. Prasterone, memantine, ketamine, and DOV216,303 attenuated and CPG36742 enhanced the pattern of vocalizations in the first phase. Prasterone, ketamine, mifepristone, DOV216,303, and CPG36742 attenuated and memantine and antalarmin enhanced the pattern of vocalizations in the second phase. This pattern of drug effects parallels what clinical data exist, and highlights two important characteristics of this dual-screening assay. For the compounds tested, this chick model identified phase II and III clinical failures (e.g. memantine and antalarmin) and has the potential to reveal possible contraindications of compounds (i.e. CPG36742) in cases where anxiety symptoms are concomitant with a depressive episode.

Manatee (Trichechus manatus) vocalization usage in relation to environmental noise levels

Noise can interfere with acoustic communication by masking signals that contain biologically important information. Communication theory recognizes several ways a sender can modify its acoustic signal to compensate for noise, including increasing the source level of a signal, its repetition, its duration, shifting frequency outside that of the noise band, or shifting the timing of signal emission outside of noise periods. The extent to which animals would be expected to use these compensation mechanisms depends on the benefit of successful communication, risk of failure, and the cost of compensation. Here we study whether a coastal marine mammal, the manatee, can modify vocalizations as a function of behavioral context and ambient noise level. To investigate whether and how manatees modify their vocalizations, natural vocalization usage and structure were examined in terms of vocalization rate, duration, frequency, and source level. Vocalizations were classified into two call types, chirps and squeaks, which were analyzed independently. In conditions of elevated noise levels, call rates decreased during feeding and social behaviors, and the duration of each call type was differently influenced by the presence of calves. These results suggest that ambient noise levels do have a detectable effect on manatee communication and that manatees modify their vocalizations as a function of noise in specific behavioral contexts.

Comparison of manual and automated methods for identifying target sounds in audio recordings of Pileated, Pale-billed, and putative Ivory-billed woodpeckers

Although offering many benefits over manual recording and survey techniques for avian field studies, automated sound recording systems produce large datasets that must be carefully examined to locate sounds of interest. We compared two methods for locating target sounds in continuous sound recordings: (1) a manual method using computer software to provide a visual representation of the recording as a sound spectrogram and (2) an automated method using sound analysis software preprogrammed to identify specific target sounds. For both methods, we examined the time required to process a 24-h recording, scanning accuracy, and scanning comprehensiveness using four different target sounds of Pileated Woodpeckers {Dryocopus pileatus), Pale billed Woodpeckers {Campephilus guatemalensis), and putative Ivory-billed Woodpeckers {Campehilusprincipalis). We collected recordings from the bottomland forests of Florida and the Neotropical dry forests of Costa Rica, and compared manual versus automated cross-correlation scanning techniques. The automated scanning method required less time to process sound recordings, but made more false positive identifications and was less comprehensive than the manual method, identifying significantly fewer target sounds. Although the automated scanning method offers a fast and economic alternative to traditional manual efforts, our results indicate that manual scanning is best for studies requiring an accurate account of temporal patterns in call frequency and for those involving birds with low vocalization rates.

Cross-fostering diminishes song discrimination in zebra finches (Taeniopygia guttata)

Song-production, -discrimination, and -preferences in oscine birds are dually influenced by species identity and the ontogenetic environment. The cross-fostering of a model species for recognition research, the zebra finch (Taeniopygia guttata) into heterospecific nests of the Bengalese finch (Lonchura striata vars. domestica) allows an exploration of the sensory limits of early development and the effects of species-specific acoustic cues upon song discrimination in adulthood. To quantify the song preferences of female and male normal-reared (control) and Bengalese finch fostered zebra finches, we recorded multiple behavioral measures, including spatial proximity, vocalization rates and response latency, during sequential song-playback choice-trials using both tutor species' songs and the songs of two other ecologically relevant Australian species, the owl finch (Taeniopygia bichenovii) and the star finch (Neochmia ruficauda). Response strength was variable between the different measures, but no differences were detected within the specific behavioral responses towards the song playbacks of the two sexes. Control subjects strongly preferred their own species' songs while Bengalese-fostered zebra finches exhibited reduced song discrimination between con-, tutor-, and heterospecific songs. Overall behavioral responsiveness was also modulated by social ontogeny. These results indicate a difference in the strength of preference for song that is dependent on the species identity of the rearing environment in oscine birds and illustrate the role of multiple behavioral measures and ecologically relevant stimulus species selection in behavioral research using zebra finches.

Dopamine's role in social modulation of infant isolation‐induced vocalization: II. Maternally modulated infant separation responses are regulated by D1‐ and D2‐family dopamine receptors

Mammalian infant behavior directed toward caregivers is critical to survival and may play a role in establishing social bonds. Most mammalian infants vocalize when isolated. Rat pups vocalize at a higher rate when isolated following an interaction with an adult female than after an interaction with littermates, a phenomenon termed maternal potentiation. We previously reported that the D2 receptor family agonist quinpirole disrupts maternal potentiation at a dose that does not alter vocalization rate following contact with littermates. Here we further examine the role of dopamine in maternal potentiation by testing effects of both D1 and D2 receptor family ligands, alone and in combination, on maternal potentiation. We tested the drugs' effects on isolation vocalization subsequent to littermate contact and then another isolation preceded by a brief "reunion" period of exposure either to the anesthetized dam or a handling-only "pickup" condition. D2 receptor stimulation blocked the increase in vocalizations following reunion with the dam. The D2 agonist effect in the dam-reunion condition was much larger than its small effect in the pickup condition, providing further evidence that D2 receptors exert a selective modulation of maternal potentiation. On the other hand, systemic administration of the D1 agonist SKF81297 reduced isolation vocalizations nonspecifically, across all the experimental conditions. Finally, the D1 and D2 receptor dual antagonist, alpha-flupenthixol, increased isolation vocalizations and disrupted potentiation, but at doses that also inhibited locomotion. We conclude that D2 receptor family activation has a more selective effect of disrupting maternal potentiation than D1 receptor family activation.

Effects on hamster vocalization and aggression of carbachol injections into the MPOA/AH

Recent work has shown that microinjections of the cholinergic agonist carbachol into the preoptic area (MPOA) increase 20–30 kHz ultrasonic vocalization in rats. This response could be interpreted as a quite specific and direct effect on a central mechanism for vocalization or ultrasound production. Alternatively, it could reflect a more general drug-induced increase in defensiveness or defensive aggression. Two studies were conducted to distinguish these possibilities. In both, MPOA carbachol treatments very similar to those in previous work (unilateral injections into the MPOA/AH of 1 µg of carbachol in 0.2 µl of saline) were administered to female hamsters. The first study focused on the rate of ultrasonic courtship vocalization, finding it to decrease after treatment. This result is inconsistent with the view that cholinergic agonists directly stimulate vocalization. In contrast, although it does not completely exclude an effect on a mechanism for vocalization, it provides at least suggestive support for an interpretation in terms of defensiveness: Because hamster ultrasounds convey sexual readiness rather than alarm or aggressiveness, they would be expected to decrease in the event of a drug-induced increase in an incompatible motivational or emotional state. The second study exploited the aggressiveness of hamsters to even more directly test carbachol's ability to increase defensiveness or defensive aggression. Its results showed that minimally-estrous female subjects bit their male pursuers more quickly if recently treated with carbachol rather than placebo. Taken together, both results support the existence of a cholinergic system that extends through the MPOA and regulates defensiveness or a related motivational or emotional state.

Vocal behavior of Florida manatees during vessel approaches.

Florida manatees (Trichechus manatus latirostris) spend much of their lives in an “urbanized” ocean with high levels of vessel traffic being common during much of the year. To explore the detailed acoustic and motor behavior of manatees during vessel approaches, digital archival tags were attached to animals in the waters of southwest Florida in 2007 and 2008. These tags record sounds produced by the manatee and other sounds in the environment up to 32 kHz as well as sampling a suite of behavioral and environmental sensors at 50 Hz. The vocal behavior of manatees before, during, and after vessel approaches was investigated. Vocalizations were assigned to the tagged manatee by the higher amplitude and the presence of higher frequency harmonics compared to signals produced by nearby animals. Dolphins have been found to increase their vocalization rate at the onset of vessel approaches, and we have numerous vessel approaches to 20 individuals to evaluate manatee vocal behavior in these contexts. We will present results from single as well as multiple boat approaches and compare these vocal rates to periods without boats. In addition to reporting vocalization rates during vessel approaches, we are investigating the types of signals used by manatees in these situations.

The effects of selective breeding for differential rates of 50‐kHz ultrasonic vocalizations on emotional behavior in rats

Fifty-kHz ultrasonic vocalizations have previously been shown to be positively correlated with reward and appetitive social behavior in rats, and to reflect a positive affective state. In this study, rats selectively bred for high and low rates of 50-kHz vocalizations as juveniles were tested as adults in a battery of behavioral tests for social/emotional behaviors. We found that animals selectively bred for high rates of 50-kHz vocalizations exhibited more crosses into the center area of the open field apparatus, were more likely to show a preference for a dilute sucrose solution (.8%) compared to tap water, and were less aggressive than randomly bred animals. Conversely, animals bred for low rates of 50-kHz calls produced more fecal boli during both open field testing and "tickling" stimulation, and made less contact with conspecifics in a social interaction test compared to randomly bred animals. We also observed that low line rats have elevated brain levels of cholecystokinin (CCK) in the cortex, which is consistent with literature showing that CCK content in the cortex is positively correlated with rates of aversive 22-kHz USVs. Conversely, high line animals had elevated levels of met-enkephalin in several brain regions, which is consistent with the role of endogenous-opioids in the generation 50-kHz USVs and positive affect. These results suggest that animals bred for high rates of 50-kHz may show a stress resilient phenotype, whereas low line rats may show a stress prone phenotype. As such these animals could provide novel insights into the neurobiology of emotion.

Diel periodicity in both sei whale vocalization rates and the vertical migration of their copepod prey observed from ocean gliders

The daily activity cycles of marine predators may be dictated in large part by the timing of prey availability. For example, recent studies have observed diel periodicity in baleen whale vocalization rates that are thought to be governed by the diel vertical migration of their zooplanktonic prey. We addressed this hypothesis by studying associations between sei whale (Balaenoptera borealis) vocalization rates, oceanographic conditions, and the vertical distribution of the whales' prey, the calanoid copepod Calanus finmarchicus, during May 2005 in the southwestern Gulf of Maine using an array of autonomous ocean gliders. Each of the four gliders was equipped with sensors to measure temperature, salinity, and chlorophyll fluorescence. Three of the four gliders carried a digital acoustic recorder and the fourth carried a 1‐MHz acoustic Doppler current profiler. We observed strong diel periodicity in the acoustic backscatter measured by the current profiler that we attribute (based on a corroborating shipboard study) to the diel vertical migration of C. finmarchicus. Sei whale vocalization rates also exhibited diel periodicity, with more calls detected during the daytime when C. finmarchicus was observed at depth. We found no evidence to suggest that the observed patterns in sei whale calling rates were attributable to diel periodicity in background noise or acoustic propagation conditions. Sei whales are adept at foraging on nearsurface aggregations of C. finmarchicus; therefore we expect that the whales were feeding at night. We hypothesize that calling rates are reduced at night while the whales are feeding, but increase with social activity during the day when copepods are either more difficult or less efficient to capture at depth. The gliders' persistence during adverse weather conditions experienced during the study allowed continuous collocated observations of whale vocalization behavior and oceanographic conditions that have not been previously possible with traditional shipboard techniques.

Spatial and temporal dynamics at manakin leks: reconciling lek traditionality with male turnover

Leks, display grounds where males congregate and females visit to copulate, are typically traditional in location, despite often high turnover of individual males. How leks can persist in face of male turnover is not well understood, in part due to a lack of detailed field data allowing for a clear understanding of lek dynamics. We followed the fate of individual males at 11 to 15 leks of the blue-crowned manakin Lepidothrix coronata across four breeding seasons to gain insights on how leks are formed and changed in space and time. Between years, leks were traditional in location despite changes in territory ownership due to male disappearance and recruitment. New males were equally likely to recruit by taking over existing territories or by establishing new territories. Recruitment was influenced by age, as recruits were more likely to be adults than subadults. Lek size did not affect the probabilities of a male recruiting or persisting at a territory, and vocalization rate, a correlate of mating success in this population, did not affect male persistence. We used our field data to model changes in lek size and composition over longer periods of time (100 years) to understand how lek traditionality can be reconciled with high male turnover. Our simulations showed that leks in our population rapidly stabilize in size despite changes in territory ownership and that rates of male recruitment and disappearance compensate each other, such that leks have the potential to persist for several decades after the original males have disappeared from them.

SEX-ROLE REVERSAL IN SONG? FEMALES SING MORE FREQUENTLY THAN MALES IN THE STREAK-BACKED ORIOLE

Abstract Birds in which both sexes produce complex song are more common in the tropics than in the temperate north, where typically only males sing. Yet surprisingly little is known about female song characteristics in most tropical species. Here we present a comparison of female and male singing behaviors in the Streak-backed Oriole (Icterus pustulatus), a tropical songbird in which both sexes perform solo songs. Females sing much more frequently than males and produce songs with similar acoustic complexity. Rates of singing by both sexes were higher during breeding than postbreeding while the rates of most other vocalizations did not change, suggesting that song plays an important role in breeding. To our knowledge, this is the first reported species in which females regularly sing at higher rates than males; however, few studies have examined female song in other sexually monomorphic or weakly dimorphic species, so such patterns might not be unique.

Seasonal Changes of Vocal Rates and Their Relation to Territorial Status in Male Galápagos Sea Lions (Zalophus wollebaeki)

AbstractMale vocal displays play an important role in sexual selection through both male–male competition and female choice. While this is supported by numerous studies in birds, much less attention has been paid to the role of such displays in mammals. We investigated the function of vocal displays in a polygynous mammal, the Galápagos sea lion (Zalophus wollebaeki). In our study population a large proportion of mature males are unable to establish a territory, providing the opportunity to compare the vocal behaviour between territorial and non‐territorial males. We examined how seasonal patterns of vocalizations differed between territorial and non‐territorial males and how the number of females present in a territory influenced behaviour of territorial males. We found that territorial males vocalized at higher rates than non‐territorial males, and territorial males vocalized more at the onset than towards the end of territory tenure. During the onset of territory‐tenure vocalizations of territorial males were directed more often towards other males than females. Furthermore, we found that vocalizations of territorial males were not only given in male–male interactions, but were also actively directed towards females. Territorial males vocalized at higher rates when more females were present in their territory. Our results suggest that vocalizations are important in male–male interactions, are relevant in territorial disputes and are used as a proxy for females to assess a male’s quality.

Go, Dog, Go: Maze Training AIBO vs. a Live Dog, An Exploratory Study

ABSTRACTThe purpose of this study was to investigate differences in interaction and attribution when participants directed either a robotic dog (AIBO) or a live dog. Twenty-nine participants (20 female, 9 male) directed one of the two entities, a live dog or AIBO, through a complex maze from a remote location by providing voice commands. Participants were given identical feedback regarding the entity's performance during the maze task. While directing the dog or AIBO through the maze, participants rated their own moods. Following the maze task, participants rated the dog or AIBO on a variety of attributes. Vocal data were analyzed for content and fundamental frequency. Results indicate that although vocal content and mood ratings did not differ when participants interacted with the dog versus AIBO, fundamental frequency was higher when participants talked to the dog rather than the AIBO. The dog and AIBO were also rated differently on several attributes after the maze task. Overall, the results suggest that human responses during interactions with live and robotic animals can be superficially similar, yet distinctly different when examined at a deeper level.

Ventral striatum dopamine D2 receptor activity inhibits rat pups' vocalization response to loss of maternal contact.

Most mammalian infants vocalize when isolated. The vocalization promotes caregiver proximity, which is critical to survival. If, before isolation, a rat pup has contact with its dam, its isolation vocalization rate is increased (maternal potentiation) relative to isolation preceded only by littermate contact. Prior work showed that systemic administration of a D2 receptor agonist blocks maternal potentiation at doses that do not alter baseline vocalization. In this study, infusion of quinpirole (2 microg/side) into the nucleus accumbens also blocks maternal potentiation. Infusion of the accumbens with the D2 antagonist raclopride (4 microg/side) prevents systemic quinpirole from blocking potentiation. Quinpirole infusion in the dorsal striatum did not affect maternal potentiation and infusion of raclopride in the dorsal striatum did not reverse the block of maternal potentiation by systemic quinpirole. Vocalization results after a second vehicle infusion on a given day are no different than the results following an initial vehicle infusion, so experimental design can not account for the effects of drug infusions. Because activity level was increased by both dorsal and ventral striatum infusions, activity level can not account for the results.