Courtship song preferences in female zebra finches are shaped by developmental auditory experience

Cortical Processing of Conspecific Vocalizations in Zebra Finches Depends on the Early Acoustical Environment

Sensory experience during development has lasting effects on perception and neural processing. Exposing animals to artificial stimuli early in life influences the tuning and functional organization of the auditory cortex, but less is known about how the rich acoustical environments experienced by vocal communicators affect the processing of complex vocalizations. Here, we show that in zebra finches (Taeniopygia guttata), a colonial-breeding songbird species, exposure to a naturalistic social-acoustical environment during development has a profound impact on cortical-level auditory responses to conspecific song. Compared to birds raised by pairs in acoustic isolation, birds raised in a breeding colony had higher average firing rates, selectivity, and discriminability, especially in the narrow-spiking, putatively inhibitory neurons of a higher-order auditory area, the caudomedial nidopallium (NCM). Neurons in colony-reared birds were also less correlated in their tuning and more efficient at encoding the spectrotemporal structure of conspecific song. These results suggest that the auditory cortex adapts to noisy, complex acoustical environments by strengthening inhibitory circuitry, functionally decoupling excitatory neurons while maintaining overall excitatory-inhibitory balance.

Social experiences shape song preference learning independently of developmental exposure to song

Communication governs the formation and maintenance of social relationships. The interpretation of communication signals depends not only on the signal's content but also on a receiver's individual experience. Experiences throughout life may interact to affect behavioural plasticity, such that a lack of developmental sensory exposure could constrain adult learning, while salient adult social experiences could remedy developmental deficits. We investigated how experiences impact the formation and direction of female auditory preferences in the zebra finch. Zebra finches form long-lasting pair bonds and females learn preferences for their mate's vocalizations. We found that after 2 weeks of cohabitation with a male, females formed pair bonds and learned to prefer their partner's song regardless of whether they were reared with ('normally reared') or without ('song-naive') developmental exposure to song. In contrast, females that heard but did not physically interact with a male did not prefer his song. In addition, previous work has found that song-naive females do not show species-typical preferences for courtship song. We found that cohabitation with a male ameliorated this difference in preference. Thus, courtship and pair bonding, but not acoustic-only interactions, strongly influence preference learning regardless of rearing experience, and may dynamically drive auditory plasticity for recognition and preference.

Tracing the development of learned song preferences in the female zebra finch brain with functional magnetic resonance imaging

In sexually dimorphic zebra finches (Taeniopygia guttata), only males learn to sing their father's song, whereas females learn to recognize the songs of their father or mate but cannot sing themselves. Memory of learned songs is behaviorally expressed in females by preferring familiar songs over unfamiliar ones. Auditory association regions such as the caudomedial mesopallium (CMM; or caudal mesopallium) have been shown to be key nodes in a network that supports preferences for learned songs in adult females. However, much less is known about how song preferences develop during the sensitive period of learning in juvenile female zebra finches. In this study, we used blood-oxygen level-dependent (BOLD) functional magnetic resonance imaging (fMRI) to trace the development of a memory-based preference for the father's song in female zebra finches. Using BOLD fMRI, we found that only in adult female zebra finches with a preference for learned song over novel conspecific song, neural selectivity for the father's song was localized in the thalamus (dorsolateral nucleus of the medial thalamus; part of the anterior forebrain pathway, AFP) and in CMM. These brain regions also showed a selective response in juvenile female zebra finches, although activation was less prominent. These data reveal that neural responses in CMM, and perhaps also in the AFP, are shaped during development to support behavioral preferences for learned songs.

Machine learning and statistical classification of birdsong link vocal acoustic features with phylogeny

Birdsong is a longstanding model system for studying evolution and biodiversity. Here, we collected and analyzed high quality song recordings from seven species in the family Estrildidae. We measured the acoustic features of syllables and then used dimensionality reduction and machine learning classifiers to identify features that accurately assigned syllables to species. Species differences were captured by the first 3 principal components, corresponding to basic frequency, power distribution, and spectrotemporal features. We then identified the measured features underlying classification accuracy. We found that fundamental frequency, mean frequency, spectral flatness, and syllable duration were the most informative features for species identification. Next, we tested whether specific acoustic features of species' songs predicted phylogenetic distance. We found significant phylogenetic signal in syllable frequency features, but not in power distribution or spectrotemporal features. Results suggest that frequency features are more constrained by species' genetics than are other features, and are the best signal features for identifying species from song recordings. The absence of phylogenetic signal in power distribution and spectrotemporal features suggests that these song features are labile, reflecting learning processes and individual recognition.

Song Preference in Female and Juvenile Songbirds: Proximate and Ultimate Questions

Birdsong has long been a subject of extensive research in the fields of ethology as well as neuroscience. Neural and behavioral mechanisms underlying song acquisition and production in male songbirds are particularly well studied, mainly because birdsong shares some important features with human speech such as critical dependence on vocal learning. However, birdsong, like human speech, primarily functions as communication signals. The mechanisms of song perception and recognition should also be investigated to attain a deeper understanding of the nature of complex vocal signals. Although relatively less attention has been paid to song receivers compared to signalers, recent studies on female songbirds have begun to reveal the neural basis of song preference. Moreover, there are other studies of song preference in juvenile birds which suggest possible functions of preference in social context including the sensory phase of song learning. Understanding the behavioral and neural mechanisms underlying the formation, maintenance, expression, and alteration of such song preference in birds will potentially give insight into the mechanisms of speech communication in humans. To pursue this line of research, however, it is necessary to understand current methodological challenges in defining and measuring song preference. In addition, consideration of ultimate questions can also be important for laboratory researchers in designing experiments and interpreting results. Here we summarize the current understanding of song preference in female and juvenile songbirds in the context of Tinbergen's four questions, incorporating results ranging from ethological field research to the latest neuroscience findings. We also discuss problems and remaining questions in this field and suggest some possible solutions and future directions.

Auditory and sexual preferences for a father's song can co-emerge in female Bengalese finches

Birdsong is an important communication signal used in mate choice. In some songbird species, only the males produce songs. While the females of those species do not sing, they are sensitive to inter- and intra-species song variations, and the song preferences of females depend on their developmental experiences and/or genetic predispositions. For example, in Bengalese finches and zebra finches, adult females prefer the song to which they were exposed early in life, such as the father’s song. In the current study, we aimed to test whether the preference for the father’s song, as reported in previous Bengalese finch studies, can be interpreted as a mating preference. For this purpose, the subjects were raised exclusively with their family until they became sexually mature and then tested as adults. We measured copulation solicitation displays during playbacks of the father’s song vs. unfamiliar conspecific songs and found that across individuals, the father’s song elicited more displays than other songs. In addition, we analyzed if a bird’s response to a given song could be predicted by the level of similarity of that song to the father’s song. Although the birds expressed more displays to songs with greater similarity to the father’s song, the effect was not statistically significant. These results suggest that female Bengalese finches can develop a strong mating preference for the father’s song if they are exclusively exposed to the father’s song early in life. However, it is not clear if such a preference generalizes to other cases in which birds are exposed to multiple male songs during development. In order to fully elucidate the possible contribution of experience and genetic factors in the development of female song preference in this species, future studies will need more detailed manipulation and control of the rearing conditions, including cross-fostering.

Evolving the capacity for socially guided vocal learning in songbirds: a preliminary study

Socially guided vocal learning, the ability to use contingent reactions from social partners to guide immature vocalizations to more mature forms, is thought to be a rare ability known to be used only by humans, marmosets and two unrelated songbird species (brown-headed cowbirds and zebra finches). However, this learning strategy has never been investigated in the vast majority of species that are known to modify their vocalizations over development. We propose a novel, preliminary evolutionary modelling approach that uses ecological, reproductive and developmental traits to predict which species may incorporate social influences as part of their vocal learning system. We demonstrate our model using data from 28 passerines. We found three highly predictive traits: temporal overlap between sensory (memorization) and sensorimotor (practice) phases of song learning, song used for mate attraction, and social gregariousness outside the breeding season. Species with these traits were distributed throughout the clade, suggesting that a trait-based approach may yield new insights into the evolution of learning strategies that cannot be gleaned from phylogenetic relatedness alone. Our model suggests several previously uninvestigated and unexpected species as likely socially guided vocal learners and offers new insight into the evolution and development of vocal learning. This article is part of the theme issue 'Vocal learning in animals and humans'.

Aromatase and nonaromatase neurons in the zebra finch secondary auditory forebrain are indistinct in their song-driven gene induction and intrinsic electrophysiological properties

Estrogens support major brain functions including cognition, reproduction, neuroprotection and sensory processing. Neuroestrogens are synthesized within some brain areas by the enzyme aromatase and can rapidly modulate local circuit functions, yet the cellular physiology and sensory-response profiles of aromatase neurons are essentially unknown. In songbirds, social and acoustic stimuli drive neuroestrogen elevations in the auditory forebrain caudomedial nidopallium (NCM). In both males and females, neuroestrogens rapidly enhance NCM auditory processing and auditory learning. Estrogen-producing neurons in NCM may therefore exhibit distinguishing profiles for sensory-activation and intrinsic electrophysiology. Here, we explored these questions using both immunocyctochemistry and electrophysiological recordings. Immunoreactivity for aromatase and the immediate early gene EGR1, a marker of activity and plasticity, were quantified in NCM of song-exposed animals versus silence-exposed controls. Using whole-cell patch clamp recordings from NCM slices, we also documented the intrinsic excitability profiles of aromatase-positive and aromatase-negative neurons. We observed that a subset of aromatase neurons were significantly activated during song playback, in both males and females, and in both hemispheres. A comparable population of non-aromatase-expressing neurons were also similarly driven by song stimulation. Membrane properties (i.e., resting membrane potential, rheobase, input resistance and multiple action potential parameters) were similarly indistinguishable between NCM aromatase and non-aromatase neurons. Together, these findings demonstrate that aromatase and non-aromatase neurons in NCM are indistinct in terms of their intrinsic electrophysiology and responses to song. Nevertheless, such similarities in response properties may belie more subtle differences in underlying conductances and/or computational roles that may be crucial to their function.

A small vocal repertoire during the breeding season expresses complex behavioral motivations and individual signature in the common coot

Background

Although acoustic communication plays an essential role in the social interactions of Rallidae, our knowledge of how Rallidae encode diverse types of information using simple vocalizations is limited. We recorded and examined the vocalizations of a common coot (Fulica atra) population during the breeding season to test the hypotheses that 1) different call types can be emitted under different behavioral contexts, and 2) variation in the vocal structure of a single call type may be influenced both by behavioral motivations and individual signature. We measured a total of 61 recordings of 30 adults while noting the behavioral activities in which individuals were engaged. We compared several acoustic parameters of the same call type emitted under different behavioral activities to determine how frequency and temporal parameters changed depending on behavioral motivations and individual differences.

Results

We found that adult common coots had a small vocal repertoire, including 4 types of call, composed of a single syllable that was used during 9 types of behaviors. The 4 calls significantly differed in both frequency and temporal parameters and can be clearly distinguished by discriminant function analysis. Minimum frequency of fundamental frequency (F0min) and duration of syllable (T) contributed the most to acoustic divergence between calls. Call a was the most commonly used (in 8 of the 9 behaviors detected), and maximum frequency of fundamental frequency (F0max) and interval of syllables (TI) contributed the most to variation in call a. Duration of syllable (T) in a single call a can vary with different behavioral motivations after individual vocal signature being controlled.

Conclusions

These results demonstrate that several call types of a small repertoire, and a single call with function-related changes in the temporal parameter in common coots could potentially indicate various behavioral motivations and individual signature. This study advances our knowledge of how Rallidae use “simple” vocal systems to express diverse motivations and provides new models for future studies on the role of vocalization in avian communication and behavior.

Neurogenomic insights into the behavioral and vocal development of the zebra finch

The zebra finch (Taeniopygia guttata) is a socially monogamous and colonial opportunistic breeder with pronounced sexual differences in singing and plumage coloration. Its natural history has led to it becoming a model species for research into sex differences in vocal communication, as well as behavioral, neural and genomic studies of imitative auditory learning. As scientists tap into the genetic and behavioral diversity of both wild and captive lineages, the zebra finch will continue to inform research into culture, learning, and social bonding, as well as adaptability to a changing climate.

Behavioral discrimination and time-series phenotyping of birdsong performance

Variation in the acoustic structure of vocal signals is important to communicate social information. However, relatively little is known about the features that receivers extract to decipher relevant social information. Here, we took an expansive, bottom-up approach to delineate the feature space that could be important for processing social information in zebra finch song. Using operant techniques, we discovered that female zebra finches can consistently discriminate brief song phrases ("motifs") from different social contexts. We then applied machine learning algorithms to classify motifs based on thousands of time-series features and to uncover acoustic features for motif discrimination. In addition to highlighting classic acoustic features, the resulting algorithm revealed novel features for song discrimination, for example, measures of time irreversibility (i.e., the degree to which the statistical properties of the actual and time-reversed signal differ). Moreover, the algorithm accurately predicted female performance on individual motif exemplars. These data underscore and expand the promise of broad time-series phenotyping to acoustic analyses and social decision-making.

Sex differences in the development and expression of a preference for familiar vocal signals in songbirds

Production and perception of birdsong critically depends on early developmental experience. In species where singing is a sexually dimorphic trait, early life song experience may affect later behavior differently between sexes. It is known that both male and female songbirds acquire a life-long memory of early song experience, though its function remains unclear. In this study, we hypothesized that male and female birds express a preference for their fathers' song, but do so differently depending on the developmental stage. We measured preference for their father's song over an unfamiliar one in both male and female Bengalese finches at multiple time points across ontogeny, using phonotaxis and vocal response as indices of preference. We found that in males, selective approach to their father's song decreased as they developed while in females, it remained stable regardless of age. This may correspond to a higher sensitivity to tutor song in young males while they are learning and a retained sensitivity in females because song is a courtship signal that is used throughout life. In addition, throughout development, males vocalized less frequently during presentation of their father's song compared to unfamiliar song, whereas females emitted more calls to their father's song. These findings contribute to a deeper understanding of why songbirds acquire and maintain such a robust song memory.

High responsiveness of auditory neurons to specific combination of acoustic features in female songbirds

Zebra finch (Taeniopygia guttata) is a songbird species in which males sing their unique songs to attract females who then select their preferred male. Acoustic features in the songs of individual males are important features for female auditory perception. While the male of this species is a classic model of vocal production, it has been little known about auditory processing in female. In the higher auditory brain regions, the caudomedial mesopallium (CMM) and nidopallium (NCM) contribute to female's sound recognition, we, therefore, extracted acoustic features that induce neural activities with high detection power on both regions in female finches. A multiple linear regression analysis revealed that neurons were sensitive to mean frequency and Wiener entropy. In addition, we performed an experiment with modified artificial songs and harmonic songs to directly investigate neural responsiveness for deriving further evidence for the contribution of these two acoustic features. Finally, we illustrated a specific ratio combining these two acoustic features that showed highest sensitivity to neural responsiveness, and we found that properties of sensitivity are different between CMM and NCM. Our results indicate that the mixture of the two acoustic features with the specific ratio is important in the higher auditory regions of female songbirds, and these two regions have differences in encoding for sensitivity to these acoustic features.

Early Auditory Experience Modifies Neuronal Firing Properties in the Zebra Finch Auditory Cortex

Songbirds learn to sing much as humans learn to speak. In zebra finches, one of the premier songbird models, males learn to sing for later courtship through a multistep learning process during the developmental period. They first listen to and memorize the song of a tutor (normally their father) during the sensory learning period. Then, in the subsequent sensory-motor learning phase (with large overlap), they match their vocalizations to the memorized tutor song via auditory feedback and develop their own unique songs, which they maintain throughout their lives. Previous studies have suggested that memories of tutor songs are shaped in the caudomedial nidopallium (NCM) of the brain, which is analogous to the mammalian higher auditory cortex. Isolation during development, which extends the sensory learning period in males, alters song preference in adult females, and NCM inactivation decreases song preference. However, the development of neurophysiological properties of neurons in this area and the effect of isolation on these neurons have not yet been explained. Here, we performed whole-cell patch-clamp recording on NCM neurons from juvenile zebra finches during the sensory learning period, 20, 40, or 60 days post-hatching (DPH) and examined their neurophysiological properties. In contrast to previous reports in adult NCM neurons, the majority of NCM neurons of juvenile zebra finches showed spontaneous firing with or without burst firing patterns, and the percentage of neurons that fired increased in the middle of the sensory learning period (40 DPH) and then decreased at the end (60 DPH) in both males and females. We further found that auditory isolation from tutor songs alters developmental changes in the proportions of firing neurons both in males and females, and also changes those of burst neurons differently between males that sing and females that do not. Taken together, these findings suggest that NCM neurons develop their neurophysiological properties depending on auditory experiences during the sensory song learning period, which underlies memory formation for song learning in males and song discrimination in females.

Neural and molecular mechanisms underlying female mate choice decisions in vertebrates

Female mate choice is a dynamic process that allows individuals to selectively mate with those of the opposite sex that display a preferred set of traits. Because in many species males compete with each other for fertilization opportunities, female mate choice can be a powerful agent of sexual selection, often resulting in highly conspicuous traits in males. Although the evolutionary causes and consequences of the ornamentation and behaviors displayed by males to attract mates have been well studied, embarrassingly little is known about the proximate neural mechanisms through which female choice occurs. In vertebrates, female mate choice is inherently a social behavior, and although much remains to be discovered about this process, recent evidence suggests the neural substrates and circuits underlying other fundamental social behaviors (such as pair bonding, aggression and parental care) are likely similarly recruited during mate choice. Notably, female mate choice is not static, as social and ecological environments can shape the brain and, consequently, behavior in specific ways. In this Review, we discuss how social and/or ecological influences mediate female choice and how this occurs within the brain. We then discuss our current understanding of the neural substrates underlying female mate choice, with a specific focus on those that also play a role in regulating other social behaviors. Finally, we propose several promising avenues for future research by highlighting novel model systems and new methodological approaches, which together will transform our understanding of the causes and consequences of female mate choice.

Experience- and Sex-Dependent Intrinsic Plasticity in the Zebra Finch Auditory Cortex during Song Memorization

For vocal communicators like humans and songbirds, survival and reproduction depend on highly developed auditory processing systems that can detect and differentiate nuanced differences in vocalizations, even amid noisy environments. Early auditory experience is critical to the development of these systems. In zebra finches and other songbirds, there is a sensitive period when young birds memorize a song that will serve as a model for their own vocal production. In addition to learning a specific tutor's song, the auditory system may also undergo critical developmental processes that support auditory perception of vocalizations more generally. Here, we investigate changes in intrinsic spiking dynamics among neurons in the caudal mesopallium, a cortical-level auditory area implicated in discriminating and learning species-specific vocalizations. A subset of neurons in this area only fire transiently at the onset of current injections (i.e., phasic firing), a dynamical property that can enhance the reliability and selectivity of neural responses to complex acoustic stimuli. At the beginning of the sensitive period, just after zebra finches have fledged from the nest, there is an increase in the proportion of caudal mesopallium neurons with phasic excitability, and in the proportion of neurons expressing Kv1.1, a low-threshold channel that facilitates phasic firing. This plasticity requires exposure to a complex, noisy environment and is greater in males, the only sex that sings in this species. This shift to more phasic dynamics is therefore an experience-dependent adaptation that could facilitate auditory processing in noisy, acoustically complex conditions during a key stage of vocal development.SIGNIFICANCE STATEMENT Auditory experience early in life shapes how humans and songbirds perceive the vocal communication sounds produced by their species. However, the changes that occur in the brain as this learning takes place are poorly understood. In this study, we show that in young zebra finches that are just beginning to learn the structure of their species' song, neurons in a key cortical area adapt their intrinsic firing patterns in response to the acoustic environment. In the complex, cocktail-party-like environment of a colony, more neurons adopt transient firing dynamics, which can facilitate neural coding of songs amid such challenging conditions.

Neural properties of fundamental function encoding of sound selectivity in the female avian auditory cortex

Zebra finches (Taeniopygia guttata) use their voices for communication. Song structures in the songs of individual males are important for sound recognition in females. The caudomedial mesopallium (CMM) and nidopallium (NCM) are known to be essential higher auditory regions for sound recognition. These two regions have also been discussed with respect to their fundamental functions and song selectivity. To clarify their functions and selectivity, we investigated latencies and spiking patterns and also developed a novel correlation analysis to evaluate the relationship between neural activity and the characteristics of acoustic factors. We found that the latencies and spiking patterns in response to song stimuli differed between the CMM and NCM. In addition, our correlation analysis revealed that amplitude and frequency structures were important temporal acoustic factors for both regions. Although the CMM and NCM have different fundamental functions, they share similar encoding systems for acoustic factors.

Beyond Critical Period Learning: Striatal FoxP2 Affects the Active Maintenance of Learned Vocalizations in Adulthood

In humans, mutations in the transcription factor forkhead box P2 (FOXP2) result in language disorders associated with altered striatal structure. Like speech, birdsong is learned through social interactions during maturational critical periods, and it relies on auditory feedback during initial learning and on-going maintenance. Hearing loss causes learned vocalizations to deteriorate in adult humans and songbirds. In the adult songbird brain, most FoxP2-enriched regions (e.g., cortex, thalamus) show a static expression level, but in the striatal song control nucleus, area X, FoxP2 is regulated by singing and social context: when juveniles and adults sing alone, its levels drop, and songs are more variable. When males sing to females, FoxP2 levels remain high, and songs are relatively stable: this “on-line” regulation implicates FoxP2 in ongoing vocal processes, but its role in the auditory-based maintenance of learned vocalization has not been examined. To test this, we overexpressed FoxP2 in both hearing and deafened adult zebra finches and assessed effects on song sung alone versus songs directed to females. In intact birds singing alone, no changes were detected between songs of males expressing FoxP2 or a GFP construct in area X, consistent with the marked stability of mature song in this species. In contrast, songs of males overexpressing FoxP2 became more variable and were less preferable to females, unlike responses to songs of GFP-expressing control males. In deafened birds, song deteriorated more rapidly following FoxP2 overexpression relative to GFP controls. Together, these experiments suggest that behavior-driven FoxP2 expression and auditory feedback interact to precisely maintain learned vocalizations.

Ability to modulate birdsong across social contexts develops without imitative social learning

Many important behaviours are socially learned. For example, the acoustic structure of courtship songs in songbirds is learned by listening to and interacting with conspecifics during a sensitive period in development. Signallers modify the spectral and temporal structures of their vocalizations depending on the social context, but the degree to which this modulation requires imitative social learning remains unknown. We found that male zebra finches (Taeniopygia guttata) that were not exposed to context-dependent song modulations throughout development significantly modulated their song in ways that were typical of socially reared birds. Furthermore, the extent of these modulations was not significantly different between finches that could or could not observe these modulations during tutoring. These data suggest that this form of vocal flexibility develops without imitative social learning in male zebra finches.

Developmental auditory exposure shapes responses of catecholaminergic neurons to socially-modulated song

Developmental sensory experience is critical to the tuning of sensory systems and can shape perceptual abilities and their neural substrates. Neuromodulators, including catecholamines, contribute to sensory plasticity in both older and younger individuals and provide a mechanism for translating sensory experience into changes in brain and behavior. Less well known, however, is whether developmental sensory experience has lasting effects on the neuromodulatory neurons themselves. Here, we used female zebra finches to investigate the degree to which developmental auditory experience can have lasting effects on the density and sensory responsiveness of catecholamine-synthesizing neuron populations. We found that hearing courtship, but not non-courtship, song increased expression of the activity-dependent immediate early gene cFOS in dopamine neurons of the caudal ventral tegmental area (VTA) and this increase was dependent on whether females heard adult song during development. Developmental song exposure also affected the density of dopamine producing neurons in the rostral VTA. In contrast, song-evoked responses in noradrenergic neurons of the Locus Coeruleus were not affected by either developmental song exposure or the social context of the stimulus. These data highlight the lasting effects that developmental auditory experience can have in shaping both the density and sensory responsiveness of dopamine neuron populations.

Auditory experience controls the maturation of song discrimination and sexual response in Drosophila

In birds and higher mammals, auditory experience during development is critical to discriminate sound patterns in adulthood. However, the neural and molecular nature of this acquired ability remains elusive. In fruit flies, acoustic perception has been thought to be innate. Here we report, surprisingly, that auditory experience of a species-specific courtship song in developing Drosophila shapes adult song perception and resultant sexual behavior. Preferences in the song-response behaviors of both males and females were tuned by social acoustic exposure during development. We examined the molecular and cellular determinants of this social acoustic learning and found that GABA signaling acting on the GABAA receptor Rdl in the pC1 neurons, the integration node for courtship stimuli, regulated auditory tuning and sexual behavior. These findings demonstrate that maturation of auditory perception in flies is unexpectedly plastic and is acquired socially, providing a model to investigate how song learning regulates mating preference in insects.

Courtship song preferences in female zebra finches are shaped by developmental auditory experience

The performance of courtship signals provides information about the behavioural state and quality of the signaller, and females can use such information for social decision-making (e.g. mate choice). However, relatively little is known about the degree to which the perception of and preference for differences in motor performance are shaped by developmental experiences. Furthermore, the neural substrates that development could act upon to influence the processing of performance features remains largely unknown. In songbirds, females use song to identify males and select mates. Moreover, female songbirds are often sensitive to variation in male song performance. Consequently, we investigated how developmental exposure to adult male song affected behavioural and neural responses to song in a small, gregarious songbird, the zebra finch. Zebra finch males modulate their song performance when courting females, and previous work has shown that females prefer the high-performance, female-directed courtship song. However, unlike females allowed to hear and interact with an adult male during development, females reared without developmental song exposure did not demonstrate behavioural preferences for high-performance courtship songs. Additionally, auditory responses to courtship and non-courtship song were altered in adult females raised without developmental song exposure. These data highlight the critical role of developmental auditory experience in shaping the perception and processing of song performance.