Vocal communication in social animals involves the production and perception of various calls that ethologists categorize into call types based on their acoustical structure and behavioral context. Whether these categories indicate distinct meanings for the animals remains unknown. The zebra finch, a gregarious songbird, uses ~11 call types that are known to communicate hunger, danger, or social conflict and to establish social contact and bonding. Using auditory discrimination tasks, we show that the birds both discriminate and categorize all the call types in their vocal repertoire. In addition, systematic errors were more frequent between call types used in similar behavioral contexts than could be expected from their acoustic similarity. Thus, zebra finches organize their calls into categories and create a mental representation of the meaning of these sounds.

Vocal production learning ("vocal learning") is a convergently evolved trait in vertebrates. To identify brain genomic elements associated with mammalian vocal learning, we integrated genomic, anatomical, and neurophysiological data from the Egyptian fruit bat (Rousettus aegyptiacus) with analyses of the genomes of 215 placental mammals. First, we identified a set of proteins evolving more slowly in vocal learners. Then, we discovered a vocal motor cortical region in the Egyptian fruit bat, an emergent vocal learner, and leveraged that knowledge to identify active cis-regulatory elements in the motor cortex of vocal learners. Machine learning methods applied to motor cortex open chromatin revealed 50 enhancers robustly associated with vocal learning whose activity tended to be lower in vocal learners. Our research implicates convergent losses of motor cortex regulatory elements in mammalian vocal learning evolution.

Some species have evolved the ability to use the sense of hearing to modify existing vocalizations, or even create new ones, which enlarges their repertoires and results in complex communication systems.1 This ability corresponds to various forms of vocal production learning that are all possessed by humans and independently displayed by distantly related vertebrates.1,2,3,4,5,6,7 Among mammals, a few species, including the Egyptian fruit bat,8,9,10 would possess such vocal production learning abilities.7 Yet the necessity of an intact auditory system for the development of the Egyptian fruit bat typical vocal repertoire has not been tested. Furthermore, a systematic causal examination of learned and innate aspects of the entire repertoire has never been performed in any vocal learner. Here we addressed these gaps by eliminating pups’ sense of hearing at birth and assessing its effects on vocal production in adulthood. The deafening treatment enabled us to both causally test these bats’ vocal learning ability and discern learned from innate aspects of their vocalizations. Leveraging wireless individual audio recordings from freely interacting adults, we show that a subset of the Egyptian fruit bat vocal repertoire necessitates auditory feedback. Intriguingly, these affected vocalizations belong to different acoustic groups in the vocal repertoire of males and females. These findings open the possibilities for targeted studies of the mammalian neural circuits that enable sexually dimorphic forms of vocal learning.

The categorization of animal vocalizations into distinct behaviorally relevant groups for communication is an essential operation that must be performed by the auditory system. This auditory object recognition is a difficult task that requires selectivity to the group identifying acoustic features and invariance to renditions within each group. We find that small ensembles of auditory neurons in the forebrain of a social songbird can code the bird’s entire vocal repertoire (∼10 call types). Ensemble neural discrimination is not, however, correlated with single unit selectivity, but instead with how well the joint single unit tunings to characteristic spectro-temporal modulations span the acoustic subspace optimized for the discrimination of call types. Thus, akin to face recognition in the visual system, call type recognition in the auditory system is based on a sparse code representing a small number of high-level features and not on highly selective grandmother neurons.

Some species have evolved the ability to use the sense of hearing to modify existing vocalizations, or even create new ones. This ability corresponds to various forms of vocal production learning that are all possessed by humans, and independently displayed by distantly related vertebrates. Among mammals, a few species, including the Egyptian fruit-bat, would possess such vocal production learning abilities. Yet the necessity of an intact auditory system for the development of the Egyptian fruit-bat typical vocal repertoire has not been tested. Furthermore, a systematic causal examination of learned and innate aspects of the entire repertoire has never been performed in any vocal learner. Here we addressed these gaps by eliminating pups' sense of hearing at birth and assessing its effects on vocal production in adulthood. The deafening treatment enabled us to both causally test these bats vocal learning ability and discern learned from innate aspects of their vocalizations. Leveraging wireless individual audio recordings from freely interacting adults, we show that a subset of the Egyptian fruit-bat vocal repertoire necessitates auditory feedback. Intriguingly, these affected vocalizations belong to different acoustic groups in the vocal repertoire of males and females. These findings open the possibilities for targeted studies of the mammalian neural circuits that enable sexually dimorphic forms of vocal learning.

Social interactions occur in group settings and are mediated by communication signals that are exchanged between individuals, often using vocalizations. The neural representation of group social communication remains largely unexplored. We conducted simultaneous wireless electrophysiological recordings from the frontal cortices of groups of Egyptian fruit bats engaged in both spontaneous and task-induced vocal interactions. We found that the activity of single neurons distinguished between vocalizations produced by self and by others, as well as among specific individuals. Coordinated neural activity among group members exhibited stable bidirectional interbrain correlation patterns specific to spontaneous communicative interactions. Tracking social and spatial arrangements within a group revealed a relationship between social preferences and intra- and interbrain activity patterns. Combined, these findings reveal a dedicated neural repertoire for group social communication within and across the brains of freely communicating groups of bats.

Obtaining a position as an independent investigator is a daunting prospect, and often requires skill sets that are not emphasized during graduate or postdoctoral training. Here, we present insight from a seminar series designed to guide young researchers looking to "make the jump", covering the fundamental steps of the job search (preparation of an application package, Skype/remote interview, campus visit, and negotiations). We summarize the many useful insights distilled throughout these roundtable sessions with the goal of providing information and guidance to a broader community of researchers on the best way to prepare for and tackle the faculty job market.

Oscines learn to produce a complex vocalization, the song, which they copy from a conspecific as young birds. The song is an attractive and conspicuous acoustic signal with striking spectral and temporal complexity. The oscine song copying behavior is also remarkable because vocal imitation is a relatively rare ability in vertebrates and because none of the nonavian species can outperform the best oscine mimics. Studies of the neurobiology of song learning have unraveled many of the mechanisms involved in this impressive vocal behavior. Song, however, is only one of the many vocalizations that are produced by oscines. The vocal repertoire of oscines is impressive not only because of the number of vocalizations produced but also because of the flexible production and usage of these sounds. This chapter reviews the vocal behavior of oscines in the framework of animal communication and examines the mechanisms underlying the production and perception of all vocalization types. The chapter also reviews how the auditory system and vocal and social brain networks might be connected to generate appropriate responses to communication calls and song. As a whole, this chapter argues that studies of the mechanisms underlying song learning and also the mechanisms underlying call plasticity, production, and perception are critical for understanding the neuroethology of vocal communication in oscines. Embracing the complexity of the vocal communication system of oscines will enhance our understanding of the brain areas that, until now, have mostly been studied in the context of song imitation.

Vocalization library of the Zebra finchThis vocalization library was collected between 2011 and 2014 at the University of California Berkeley by Julie E Elie using birds bred in the colony of the Theunissen Lab.CitationsPlease cite the following papers when using data from this collection:-> Elie JE and Theunissen FE. The vocal repertoire of the domesticated zebra finch: a data driven approach to decipher the information-bearing acoustic features of communication signals. Animal Cognition. 2016. 19(2) 285-315 DOI 10.1007/s10071-015-0933-6 [OA eScholarship]-> Elie JE and Theunissen FE. Zebra Finches identify individuals using vocal signatures unique to each call type. Nature communication. 2018. 9:4026. doi: 10.1038/s41467-018-06394-9 [OA]Annotations of vocalizations in the databaseThe database contains vocalizations both from adult and juvenile (around 30 days old) zebra finches. The sounds are organized in two zip folders according to the age of the vocalizer. The sex of adults is known. Each vocalization or sequence of vocalizations is saved as a wav file which name indicate the name of the individual (ColColxxxx), the type of vocalization (VT) and the recording date (yymmdd) using the following scheme:ColColxxxx_yymmdd-VT-zz.wavExample: GraLbl0457_110411-TetC-12.wavColColxxxx : The name of the individual is always a string of 10 letters and digits, e.g.: GraLbl0457yymmdd : The recording date always follows the first underscore as 6 digits, e.g.: 110411VT: The type of vocalization VT always follows the first hyphen and can be of various length but the first 2 letters always code the type of vocalization as described in Animal Cognition 2016 along 11 categories:Ag -> Wsst or aggressive callBe -> Begging callsDC -> Distance callDi -> Distress callLT -> Long Tonal callNe -> Nest callSo -> SongTe -> Tet callTh -> Thuk callTu -> Tuck callWh -> Whine callzz: the rendition number always follows the last hyphen.Note that some discrepancies in the naming of files are known to exist and somewhat expected since all of these 3433 files were manually annotated.ContactJulie E Elie: julie.elie@gmail.comFrederic E Theunissen : theunissen@berkeley.edu

Although information theoretic approaches have been used extensively in the analysis of the neural code, they have yet to be used to describe how information is accumulated in time while sensory systems are categorizing dynamic sensory stimuli such as speech sounds or visual objects. Here, we present a novel method to estimate the cumulative information for stimuli or categories. We further define a time-varying categorical information index that, by comparing the information obtained for stimuli versus categories of these same stimuli, quantifies invariant neural representations. We use these methods to investigate the dynamic properties of avian cortical auditory neurons recorded in zebra finches that were listening to a large set of call stimuli sampled from the complete vocal repertoire of this species. We found that the time-varying rates carry 5 times more information than the mean firing rates even in the first 100 ms. We also found that cumulative information has slow time constants (100-600 ms) relative to the typical integration time of single neurons, reflecting the fact that the behaviorally informative features of auditory objects are time-varying sound patterns. When we correlated firing rates and information values, we found that average information correlates with average firing rate but that higher-rates found at the onset response yielded similar information values as the lower-rates found in the sustained response: the onset and sustained response of avian cortical auditory neurons provide similar levels of independent information about call identity and call-type. Finally, our information measures allowed us to rigorously define categorical neurons; these categorical neurons show a high degree of invariance for vocalizations within a call-type. Peak invariance is found around 150 ms after stimulus onset. Surprisingly, call-type invariant neurons were found in both primary and secondary avian auditory areas.

Acoustic communication signals are typically generated to influence the behavior of conspecific receivers. In songbirds, for instance, such cues are routinely used by males to influence the behavior of females and rival males. There is remarkable diversity in vocalizations across songbird species, and the mechanisms of vocal production have been studied extensively, yet there has been comparatively little emphasis on how the receiver perceives those signals and uses that information to direct subsequent actions. Here, we emphasize the receiver as an active participant in the communication process. The roles of sender and receiver can alternate between individuals, resulting in an emergent feedback loop that governs the behavior of both. We describe three lines of research that are beginning to reveal the neural mechanisms that underlie the reciprocal exchange of information in communication. These lines of research focus on the perception of the repertoire of songbird vocalizations, evaluation of vocalizations in mate choice, and the coordination of duet singing.

Obtaining a position as an independent investigator is a daunting prospect, and often requires skill sets that are not emphasized during graduate or postdoctoral training. Here, we present insight from a seminar series designed to guide young researchers looking to “make the jump”, covering the fundamental steps of the job search (preparation of an application package, Skype/remote interview, campus visit, and negotiations). We summarize the many useful insights distilled throughout these roundtable sessions with the goal of providing information and guidance to a broader community of researchers on the best way to prepare for and tackle the faculty job market. After a long period of training, first as a graduate student and then typically as a postdoctoral researcher, many young investigators face the next natural step in academic career advancement: obtaining a position as an independent investigator. Many researchers realize at this stage that the training they have received in the course of their academic career does not include planning or preparation to face the (admittedly daunting) academic job market. To provide senior postdocs and graduate students with guidance and advice, we organized a seminar series devoted to demystifying the job market, clarifying the different stages of the job search, and providing an informal guide for young researchers looking to “make the jump.” The seminar series was organized as a sequence of roundtable question-and-answer discussion sessions with faculty members from the Helen Wills Neuroscience Institute at the University of California, Berkeley. These sessions covered the four fundamental steps of the job search: (a) preparation of an application package, (b) Skype/remote interview, (c) campus visit, including the job talk and “chalk” talk, and (d) negotiations. Here, we summarize the many useful insights distilled throughout these roundtable sessions with the goal of providing information and guidance to a broader community of researchers on the best way to prepare for and tackle the faculty job market, hoping to complement already existing career advice for young neuroscientists (D Belin, 2016; Hanganu-Opatz, Mameli, Káradóttir, & Spires-Jones, 2015; Káradóttir, Letzkus, Mameli, & Ribeiro, 2015; Schwabe, López-Bendito, & Ribeiro, 2016; Spires-Jones, Poirazi, & Grubb, 2016; Yaksi, Poirazi, & Hanganu-Opatz, 2016) with concrete guidance on the steps of the job search process. These sessions primary focused on job searches at institutions within the United States. However, we believe that much of the advice that was generated applies to those searching outside of the United States as well, and we specifically discuss differences that apply to the European job market (see Box 1). The data and advice presented here are focused on the US job market. However, there can be substantial differences between the US and European systems, which can lead to substantial differences in the job search process and the adequate strategy to follow. We highlight a few of them here: The first consideration after you have decided to pursue an independent position is to determine when to enter into the job market. The timing will vary from field to field; for most biomedical fields in the United States, it is common for researchers to collect 5–7 years of postdoctoral experience in 1 or 2 laboratories before heading out into the market. Have a look at the CVs of recent hires in your department and similar departments in other universities, talk to friends and get advice from your advisor(s). When should you apply for an independent position? The answer changes from field to field, but it is safe to say that most people will jump on the job market before they feel fully ready for it. A somewhat aggressive approach is a good strategy—even if it is too early, the experiences you accumulate during your first go at the job market will prove invaluable 1 or 2 years down the line, and there is always a chance that things may work out on that exploratory effort. However, you want to have a clear idea of your future research plans and the obvious downside is that looking for a job takes time. Preparing application materials, practicing talks and doing due diligence on your target departments will take time away from your research, but most of this effort is not wasted. For example, writing a research strategy will force you to think through your career and research plans, and practicing talks will make you more effective at giving public presentations. It is not necessary to wait until all of your papers are published—it is fine to have manuscripts under review, in preparation (you can include a draft in the application, if the writing is sufficiently advanced) or in publicly available repositories (e.g., arXiv and bioRxiv). Although not peer-reviewed and published, these provide the committee with an appreciation of your trajectory and your likely productivity over the next year. Committees are looking for an upward trajectory and your drafts can help make the case. Your mentor can also speak to the progress and novelty of your research in their letter of support. Online resources are a great and convenient source of job postings. Websites like HERC jobs, Science careers, AcademicKeys, NatureJobs and HigherEdJobs are popular and will allow you to filter the postings and set automated email alerts. Increasingly, Twitter is a good source of information on job positions. Departments may tweet their own announcements, and there are also specific accounts dedicated to curating and advertising positions within specific fields (e.g., @neurorumblr managed by Adam J. Calhoun). A few online forums are popular (e.g., Psychology Academic Job Search; psychjobsearch.wikidot.com) and sometimes provide crowd-sourced updates when interview invitations are extended and offers are accepted. If your university has a career development or job hub, they may be able to point you in the right direction. Sometimes job postings are circulated via internal listservs (e.g., for postdocs or graduate students). Note that each European country has its own recruitment system. In France for instance, assistant professor positions are all managed by the same website (Galaxie) which is distinct from the website managing the recruitment of permanent researchers at the CNRS (Centre National the la Recherche Scientifique). It is advisable to contact local researchers to learn more about the specificity of the country system. You should also ask your mentor, laboratory mates and colleagues whether they have any interesting leads. If you are able to make direct connections with people on hiring committees at workshops or conferences, this is an opportunity to learn more about upcoming positions at other universities and identify yourself as someone of interest to the committee. Whether you are well suited to the job posting may be a critical factor, or not at all. For some positions, the job description will be highly specific, whereas other institutions (particularly high-profile research universities) may put out job advertisements that are more broadly worded in the hope of capturing top talent, regardless of the specific profile of the applicant. Most will fall somewhere in between. Keep in mind that most job descriptions may not be entirely reflective of the wants of the search committee, so it may pay off to be aggressive with your initial selection. Apply to places where you are really willing to work, even if the description is not a perfect fit for you, but avoid putting too much work into positions that are a stretch and not your most preferred places (especially if the description is highly specific). Furthermore, if you are in doubt as to whether your application may be a reasonable fit, it is advisable to email the committee chair or listed contact person and ask them directly before you begin the application process. Most institutions follow a roughly yearly hiring cycle. In the United States, job applications are posted during summer, with the volume of postings dropping precipitously after the beginning of September, and most deadlines occur throughout the fall and early winter. Selected applicants will typically be contacted 1–2 months after the application deadline for either remote (e.g., Skype) or on-campus interviews, with most remote interviews taking place before the winter break is over. Come the new year, January through March are prime time for campus visits, and the first offers will go out sometime in spring, with the negotiations likely stretching into late spring and early summer. Depending on the timeline of the hiring department, things may be sped up (e.g., if the position needs to start in the following fall). Indeed, some departments strategically accelerate their searches with the hopes of snagging their favored candidate before other institutions have a chance to present competing offers. Although some universities do contact unsuccessful applicants, typically in spring, many universities do not send any official notification. Once again, the cycle can be slightly different in Europe; for instance, most job applications and application periods in France are strictly restricted to December for the CNRS, and February-March for assistant professor positions. Once job postings have been selected, the first step involves submitting the application materials to the hiring department. For the majority of positions, the application package will include a cover letter, a curriculum vitae (CV), a research statement and, often, a teaching statement. Some institutions, including the University of California system, also require a diversity statement, and guidelines are available. In addition, you will be asked to provide 2–5 recommendation letters from past mentors, supervisors and/or collaborators; letters may be required at the time of submission or may be requested later in the application process, although in this case, you will likely need to provide contact details of your letter writers when you submit your materials. Many positions also require that you submit reprints of your publications. If you have a manuscript submitted or under review, it is a good strategy to provide it here so that the committee can appreciate it. The written application is the first opportunity to create an impression in the minds of the committee members. However, bear in mind that committees often receive hundreds of applications—plan to include all relevant information, but be concise and to the point. Usually, only one person of the committee will have fully reviewed your application and you need to help him/her advocate for your case to the rest of the committee. The importance of clarity cannot be overstated; poor writing, which prevents the committee members from understanding who you are and what you do, is a common mistake that will significantly affect your odds. Here again, the European system might differ and in France for instance, the application package always consists in an administrative form of your official application, your CV, the final report of your thesis committee and statement(s) on your past research achievements and future research plans. The report from your thesis committee comes here in place of the traditional letters requested in the United States. Potentially the least important of all parts in the application package, the goal of the cover letter is to concisely present yourself as an applicant, highlight key aspects of your research contributions (only ideas, no details), and very briefly present your core research vision. You should be able to describe your research focus in a single sentence, so take time to craft the exact wording that captures the essence of your research plans. The letter in total should be no longer than one page. The first paragraph should include a quick introduction (“My name is Jamie and I'm writing response to your call, I work at University X, I'd like to work here, see the rest of my package”). Do not go into the details of your research project here—leave that for the research statement. The main goal in the remainder of the letter is to get people reading your materials to envision you as a colleague; therefore, it can be helpful to customize it a little to include 2–3 faculty members that would be a good fit to interact with. It is also very helpful to make direct, clear statements about what your main future research goal is so that the hiring committee has context before reading your remaining application materials. Listing the elements you included in your application package and pointing to a particular manuscript that you decided to add can also help the reviewer to read through your application more efficiently. The CV includes a list of your academic accomplishments, a list of your education (titles, institutions and date of award), publications, awards, conference presentations, teaching experience and outreach, among others. It is good to start with a biosketch-style introductory paragraph that states your interests and your position in the field. Resist the temptation to include everything you have ever done in this list—it is important to be comprehensive, but try to highlight items in order of relevance and do not pad your CV with irrelevant (albeit possibly impressive) information for the sake of adding length to the document. A good organizing list is as follows: biosketch, education, published papers, grants and awards, invited talks and posters, research experience, teaching experience, outreach and technical service (e.g., peer reviewing publications or membership on committees). One of your main goals is to highlight scientific productivity, primarily reflected in publications, honors or awards, fellowships, talks and posters. Grants and awards are very important, as they reflect your ability to write a research proposal and obtain funding. Make use of all opportunities to apply for travel awards, poster awards, and even minor or intra-departmental awards. In addition to these lists of accomplishments, it is useful to include a “recent abstracts” with most recent work, with the goal of providing evidence of a scientific trajectory. It is advisable to include publications in preparation—it will give committee members the opportunity to follow up with their progress during the recruitment process. Preprints (bioRxiv, etc.) are becoming more common and generally carry more weight than just “in preparation.” The inclusion of personal information (e.g., marital status and number of children) is a matter of personal preference, although it is uncommon in the United States and was discouraged by our faculty panel. European cultures can be different in that respect and it is advisable to inquire about the local habits. Research statements give readers a clear understanding of the important questions your research engages with, the contributions you have already made in your field, and where your research is going in the future. They are typically 3–4 pages single-spaced, but can also be strictly restricted to 2 pages in some institutions. The statement should foster excitement about your research goals and the program you envision creating. Highlight the ways in which your research is innovative, how it is positioned to answer questions that, until now, were considered unsolvable, and how you are uniquely qualified to jumpstart this line of research in a new institution. Generally, research statements will cover important work from your Ph.D. period, postdoctoral period, and describe what you will be doing in the future. Your statement should demonstrate both a broad conceptual understanding, as well as a mastery of the techniques used in your research. It is advisable to keep scientific jargon limited so that your statement is accessible to anyone in the department. In some cases, there may not be a strong narrative link between your PhD and postdoctoral research. This is okay, but there must be a coherent narrative between your current research and the research program you propose for the future. Do not underestimate the importance of detailing your plans for the future. Discussion of your future research program should constitute approximately 50% of your research statement and provide a vision of what you will be doing for the next 10 years. Provide a balance between big picture questions and specific details of how you will tackle them (think on the level of aims written for a grant, such as an NIH-R01). The faculty panel unanimously recommended the inclusion of explanatory figures (with figure legends) in the research statement. Figures are memorable and will help you and your application stand out. Figures should be clear and beautiful and can be used flexibly to communicate your conceptual framework, your techniques or your findings. A teaching statement is often, but not always, required as part of the application package. It tends to carry more weight at smaller colleges or universities that are more focused on teaching than on research. The teaching statement should be around 1 page long, with half the space devoted to teaching philosophy and experience, and the second half to courses that you would like to teach in the hiring institution. Teaching philosophy should be no longer than 2–3 sentences, explaining your approach to teaching or the reasons why you would enjoy this part of your job. For the experience part, include everything you have done: not just classes but also work as research assistant, mentoring, outreach, etc. The second part of the statement is a good opportunity for tailoring—look through the web page of the department and identify classes that are being offered that you could cover, and classes that you think would be interesting to offer but do not exist yet that you would be uniquely qualified to teach. The recommendation letters are a very important part of the committee's evaluation. Bad recommendation letters are a common cause of failure. The recommendation letters will be addressed directly to the hiring department and you will get no chance to read them during the process. Your Ph.D. and any postdoctoral advisors must be included as referees. They are the people most familiar with your work and aptitudes and omitting them would be seen as a red flag. There is some latitude in whom to request the other recommendation letters from; you can ask past collaborators, professors, graduate committee members or anybody with whom you have had a good professional relationship in the past. It is appropriate to ask your recommenders to contact the committee chair to put in a good word for you before the formal application review, although we recommend reserving this request of your letter writers for only your top priority applications. The letter can be used strategically to drive home certain points you are making in your application. If there is something you would like highlighted, you can ask your letter writers to touch on specific strengths or themes. If you are applying to a school where teaching is required, your letter writer could mention your skill in mentoring research assistants or undergraduates. Applicants are often concerned about the burden they place on their letter writers, particularly if they are applying to many positions. Some participants in our roundtable discussion used letter management resources (e.g., Interfolio) where letter writers upload their confidential reference letters once and the applicant can manage the distribution of the letters to each school they are applying to. This system had positive reviews and was flexible in allowing submission of confidential letters as attachments or as a response to an email invitation (each letter is assigned a unique e-mail address that the applicant can provide in lieu of their mentor's direct email address); however, ultimately you will be constrained by the requests of the institution's call for applicants. In recent years, the second step after the committee reviews application packages is a remote Skype or phone interview. This intermediate step between the initial application and the campus visit allows departments to sample and get a first impression from a higher number of candidates, typically 8–10 candidates. The selection committee will carry out the interview, typically led by the committee chair. It is OK to ask the committee chair for details in advance, such as who will be present for the interview, what the format is, if there are time limits, and whether or not to use slides (presented through screen share). Remote interviews range from the formal, with a set of fixed questions asked to each candidate, to the free-form. In some cases, you will be asked to prepare a small set of slides (probably 5–6) to guide the discussion. The committee members will have likely read your application materials once, or may have skimmed them before the interview, but will probably have not gone through your publications. In preparing for the interview, do not assume any specific expertise in your area or even that the research described in your application materials will be readily recalled. In this interview, you should start broad and narrow down to the details to guide the committee in understanding who you are and what your vision. You should be conscious of whom your audience is (i.e., what kind of department are you interviewing for and what their primary interests are). At this point, you really want to have identified potential collaborators in the department/university, but be honest—do not misrepresent yourself to accommodate what you think are the department needs. If you get the job you will be expected to follow through on your proposed research, and you want that to reflect who you are. Timing is essential—most often this interview will last 20–30 min, so budgeting time is important. Your introduction should take 2–3 min. This first impression is important, so practice it, polish it, tape yourself and review it. The primary goal of the committee for this interview is to assess those parts of your identity that are difficult to ascertain from the application package. For example, how much of an independent thinker you are? What's your vision for the future? Can you articulate how your previous/future research contributions have made/will make a significant impact in your area? Differentiate yourself not only from your advisor but also from the rest of the scientific community. Demonstrate how unique and exciting your research is, and make an effort to convey your enthusiasm. There are a number of common questions that can help you think through your pitch, and they may be asked outright during the interview. You should devote time to think about these; you do not necessarily want to have canned answers, but you must be able to have a clear, eloquent response. It is best to prepare and practice your short, concrete responses. A list of questions is found in Table 1. As discussed further in the next section, in most cases you should not be expecting questions about your personal life, but be prepared to redirect the discussion in case this happens. In your preparation, you should also consider interview logistics. Pick a good location (e.g., book a conference room in the department), with good acoustics and high internet speed. Test that the connection is working perfectly. It is important to make a good impression, so make sure the interview will not be interrupted and that the committee is not distracted by other things. Dressing up like you would for an in-person interview may also help get you in a professional mindset for the interview. During the remote interview, you will be doing most of the talking and it may be difficult to get read on the committee's reactions, particularly if there is no video feed. Use your pauses, and do not be afraid to ask whether you should go into more detail. It is often a good idea to check that people are following half-way through your response. Finally, be prepared to ask them a few questions of your own, for example, what is the timeline for the search. Steer away from asking concrete details about the appointment, for example, about start-up funds, salary and support. There will be time for this if you make it to the following round. Typically 1–2 months after the remote interview, the committee will have narrowed it down to the few candidates (2–5) that will be invited for a campus visit. You will travel to the campus and spend an intense 1–2 days interviewing, typically at the beginning of the year. Keep in mind that your interview starts from the moment you are picked up at the airport until you board your return plane. The standard campus visit will likely be composed of an open job talk, a follow-up chalk talk (often in the second day of your visit) and a multitude of individual meetings with faculty, the head of the department, possibly even the Dean of the college and sometimes a faculty equity advisor. You will need to give your 2–3 min introductory speech (your “elevator pitch”) on multiple occasions—prepare, practice and polish. Most of these meetings will be short (20–30 min), so the Big Picture is what matters. In some cases, you will have the chance to meet with students and postdocs (often over lunch). Do not underestimate the importance of these meetings, as students and postdocs will often be asked for feedback and therefore have a voice in who gets recruited. At night you can expect to be taken out for dinner with faculty, and sometimes for an informal coffee or maybe even beer or wine—do not let your guard down and assume you are under examination all the time. Be personable and enthusiastic—people need to get excited about you and your research. Even if you do not end up taking the job, you will interact with those people again during the course of your professional career—perhaps writing grants or papers as collaborators, or as reviewers—so use this as an opportunity to make a positive impression. You want people to envision you as a colleague. However, keep in mind that you are also interviewing them—do not hesitate to ask questions and ask what you need to learn during your visit: equipment needs, facilities, departmental support, graduate programs, tenure expectations, etc. A somewhat sensitive issue is whether you want to disclose personal details. In the United States, interviewers are not allowed to ask, and you should not feel pressured to disclose any details. Such questions include (but are not limited to) whether you are married, what does your spouse do for a living, whether you have children or whether you have plans to have children. To be clear, such a line of questioning is illegal in the United States under the Civil Rights Act, Title VII, which prohibits discrimination in employment for age, disability, national origin, pregnancy, race, religion and sex or gender. Candidates should feel free to state they are not comfortable answering that type of question, state that such questioning is illegal, or ask the relevance of the question to the position. To some, volunteering this information is not a source of discomfort and may even help you connect with your potential colleagues. In essence, you should do what feels comfortable to you. Freely sharing personal details may be a matter of personality, though be aware that there are complex implicit or explicit attitudes that may affect how such information is received (Williams and Ceci, 2015, PNAS; Moss-Racusin et al., 2015, PNAS). During the roundtable discussion, some faculty members mentioned cases in which it was advantageous for the hiring department to know that their candidate had a “two-body problem,” meaning that their partner is also in academia and will potentially require a position as well. It is sometimes possible for institutions to accommodate “spousal hires” or facilitate placement in a neighboring institution. In some cases, research universities will have infrastructure in place (e.g., dual career programs) to facilitate double hires. Such arrangements can take time and, as such, there can be advantages of exploring these possibilities early in the process, particularly if they will factor strongly in the candidate's decision (discussed further in Final Negotiations—Section 6). That said, these discussions can also be initiated once you are selected as the search committee's top candidate. Below are some specific details on how to approach the more important aspects of the visit. Congratulations—you have been offered the position, making good on all your efforts to get this far! The last part of the process involves negotiating the details of your appointment. It is likely that many of these details of your appointment have been made clear to you during the campus visit, but this will be the first time you are presented with some others and the first opportunity for you to make specific demands. Something important to realize at this point, which may be hard after a grueling selection process involving hundreds of candidates, is that you have leverage. You have been identified as the best fit for the position, and reaching consensus on such an important decision is often not trivial. In other words, if you reject the offer the search may fail, which the department will strongly want to avoid. If you have multiple offers from different institutions you are in a very strong position: sharing any other offers may help a lot and give you solid ground for some of the negotiations (e.g., start-up funds and salary offer). Note, this is another benefit of applying aggressively—the opportunity to leverage multiple offers. Let institutions know, when interviewing, if you are interviewing at or have offers from other places. Stalling for time is OK as long as you are reasonable throughout the process, and

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Chickadees produce a multi-note chick-a-dee call in multiple socially relevant contexts. One component of this call is the D note, which is a low-frequency and acoustically complex note with a harmonic-like structure. In the current study, we tested black-capped chickadees on a between-category operant discrimination task using vocalizations with acoustic structures similar to black-capped chickadee D notes, but produced by various songbird species, in order to examine the role that phylogenetic distance plays in acoustic perception of vocal signals. We assessed the extent to which discrimination performance was influenced by the phylogenetic relatedness among the species producing the vocalizations and by the phylogenetic relatedness between the subjects’ species (black-capped chickadees) and the vocalizers’ species. We also conducted a bioacoustic analysis and discriminant function analysis in order to examine the acoustic similarities among the discrimination stimuli. A previous study has shown that neural activation in black-capped chickadee auditory and perceptual brain regions is similar following the presentation of these vocalization categories. However, we found that chickadees had difficulty discriminating between forward and reversed black-capped chickadee D notes, a result that directly corresponded to the bioacoustic analysis indicating that these stimulus categories were acoustically similar. In addition, our results suggest that the discrimination between vocalizations produced by two parid species (chestnut-backed chickadees and tufted titmice) is perceptually difficult for black-capped chickadees, a finding that is likely in part because these vocalizations contain acoustic similarities. Overall, our results provide evidence that black-capped chickadees’ perceptual abilities are influenced by both phylogenetic relatedness and acoustic structure.

One of the most complex tasks performed by sensory systems is “scene analysis”: the interpretation of complex signals as behaviorally relevant objects. The study of this problem, universal to species and sensory modalities, is particularly challenging in audition, where sounds from various sources and localizations, degraded by propagation through the environment, sum to form a single acoustical signal. Here we investigated in a songbird model, the zebra finch, the neural substrate for ranging and identifying a single source. We relied on ecologically and behaviorally relevant stimuli, contact calls, to investigate the neural discrimination of individual vocal signature as well as sound source distance when calls have been degraded through propagation in a natural environment. Performing electrophysiological recordings in anesthetized birds, we found neurons in the auditory forebrain that discriminate individual vocal signatures despite long-range degradation, as well as neurons discriminating propagation distance, with varying degrees of multiplexing between both information types. Moreover, the neural discrimination performance of individual identity was not affected by propagation-induced degradation beyond what was induced by the decreased intensity. For the first time, neurons with distance-invariant identity discrimination properties as well as distance-discriminant neurons are revealed in the avian auditory cortex. Because these neurons were recorded in animals that had prior experience neither with the vocalizers of the stimuli nor with long-range propagation of calls, we suggest that this neural population is part of a general-purpose system for vocalizer discrimination and ranging. SIGNIFICANCE STATEMENT Understanding how the brain makes sense of the multitude of stimuli that it continually receives in natural conditions is a challenge for scientists. Here we provide a new understanding of how the auditory system extracts behaviorally relevant information, the vocalizer identity and its distance to the listener, from acoustic signals that have been degraded by long-range propagation in natural conditions. We show, for the first time, that single neurons, in the auditory cortex of zebra finches, are capable of discriminating the individual identity and sound source distance in conspecific communication calls. The discrimination of identity in propagated calls relies on a neural coding that is robust to intensity changes, signals' quality, and decreases in the signal-to-noise ratio.

Although a universal code for the acoustic features of animal vocal communication calls may not exist, the thorough analysis of the distinctive acoustical features of vocalization categories is important not only to decipher the acoustical code for a specific species but also to understand the evolution of communication signals and the mechanisms used to produce and understand them. Here, we recorded more than 8000 examples of almost all the vocalizations of the domesticated zebra finch, Taeniopygia guttata: vocalizations produced to establish contact, to form and maintain pair bonds, to sound an alarm, to communicate distress or to advertise hunger or aggressive intents. We characterized each vocalization type using complete representations that avoided any a priori assumptions on the acoustic code, as well as classical bioacoustics measures that could provide more intuitive interpretations. We then used these acoustical features to rigorously determine the potential information-bearing acoustical features for each vocalization type using both a novel regularized classifier and an unsupervised clustering algorithm. Vocalization categories are discriminated by the shape of their frequency spectrum and by their pitch saliency (noisy to tonal vocalizations) but not particularly by their fundamental frequency. Notably, the spectral shape of zebra finch vocalizations contains peaks or formants that vary systematically across categories and that would be generated by active control of both the vocal organ (source) and the upper vocal tract (filter).

Individual cages represent a widely used housing condition in laboratories. This isolation represents an impoverished physical and social environment in gregarious animals. It prevents animals from socializing, even when auditory and visual contact is maintained. Zebra finches are colonial songbirds that are widely used as laboratory animals for the study of vocal communication from brain to behavior. In this study, we investigated the effect of single housing on the vocal behavior and the brain activity of male zebra finches (Taeniopygia guttata): male birds housed in individual cages were compared to freely interacting male birds housed as a social group in a communal cage. We focused on the activity of septo-hypothalamic regions of the "social behavior network" (SBN), a set of limbic regions involved in several social behaviors in vertebrates. The activity of four structures of the SBN (BSTm, medial bed nucleus of the stria terminalis; POM, medial preoptic area; lateral septum; ventromedial hypothalamus) and one associated region (paraventricular nucleus of the hypothalamus) was assessed using immunoreactive nuclei density of the immediate early gene Zenk (egr-1). We further assessed the identity of active cell populations by labeling vasotocin (VT). Brain activity was related to behavioral activities of birds like physical and vocal interactions. We showed that individual housing modifies vocal exchanges between birds compared to communal housing. This is of particular importance in the zebra finch, a model species for the study of vocal communication. In addition, a protocol that daily removes one or two birds from the group affects differently male zebra finches depending of their housing conditions: while communally-housed males changed their vocal output, brains of individually housed males show increased Zenk labeling in non-VT cells of the BSTm and enhanced correlation of Zenk-revealed activity between the studied structures. These results show that housing conditions must gain some attention in behavioral neuroscience protocols.

Physiological resonance – where the physiological state of a subject generates the same state in a perceiver – has been proposed as a proximate mechanism facilitating pro-social behaviours. While mainly described in mammals, state matching in physiology and behaviour could be a phylogenetically shared trait among social vertebrates. Birds show complex social lives and cognitive abilities, and their monogamous pair-bond is a highly coordinated partnership, therefore we hypothesised that birds express state matching between mates. We show that calls of male zebra finches Taeniopygia guttata produced during corticosterone treatment (after oral administration of exogenous corticosterone and during visual separation from the partner) provoke both an increase in corticosterone concentrations and behavioural changes in their female partner compared to control calls (regular calls emitted by the same male during visual separation from the partner only), whereas calls produced during corticosterone treatment by unfamiliar males have no such effect. Irrespective of the caller status (mate/non-mate), calls' acoustic properties were predictive of female corticosterone concentration after playback, but the identity of mate calls was necessary to fully explain female responses. Female responses were unlikely due to a failure of the call-based mate recognition system: in a discrimination task, females perceive calls produced during corticosterone treatment as being more similar to the control calls of the same male than to control calls of other males, even after taking acoustical differences into account. These results constitute the first evidence of physiological resonance solely on acoustic cues in birds, and support the presence of empathic processes.

Understanding how the brain extracts the behavioral meaning carried by specific vocalization types that can be emitted by various vocalizers and in different conditions is a central question in auditory research. This semantic categorization is a fundamental process required for acoustic communication, and presupposes discriminative and invariance properties of the auditory system for conspecific vocalizations. Songbirds have been used extensively to study vocal learning, but the communicative function of all their vocalizations and their neural representation has yet to be examined. In this study, we first generated a library containing almost the entire zebra finch vocal repertoire, and organised communication calls along nine different categories according to their behavioral meaning. We then investigated the neural representations of these semantic categories in the primary and secondary auditory areas of six anesthetised zebra finches. To analyse how single units encode these call categories, we described neural responses in terms of their discrimination, selectivity and invariance properties. Quantitative measures for these neural properties were obtained with an optimal decoder using both spike counts and spike patterns. Information theoretic metrics show that almost half of the single units encode semantic information. Neurons achieve higher discrimination of these semantic categories by being more selective and more invariant. These results demonstrate that computations necessary for semantic categorization of meaningful vocalizations are already present in the auditory cortex, and emphasise the value of a neuro-ethological approach to understand vocal communication.