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Development of Auditory-Vocal Perceptual Skills in Songbirds  [PDF]
Vanessa C. Miller-Sims, Sarah W. Bottjer
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0052365
Abstract: Songbirds are one of the few groups of animals that learn the sounds used for vocal communication during development. Like humans, songbirds memorize vocal sounds based on auditory experience with vocalizations of adult “tutors”, and then use auditory feedback of self-produced vocalizations to gradually match their motor output to the memory of tutor sounds. In humans, investigations of early vocal learning have focused mainly on perceptual skills of infants, whereas studies of songbirds have focused on measures of vocal production. In order to fully exploit songbirds as a model for human speech, understand the neural basis of learned vocal behavior, and investigate links between vocal perception and production, studies of songbirds must examine both behavioral measures of perception and neural measures of discrimination during development. Here we used behavioral and electrophysiological assays of the ability of songbirds to distinguish vocal calls of varying frequencies at different stages of vocal learning. The results show that neural tuning in auditory cortex mirrors behavioral improvements in the ability to make perceptual distinctions of vocal calls as birds are engaged in vocal learning. Thus, separate measures of neural discrimination and behavioral perception yielded highly similar trends during the course of vocal development. The timing of this improvement in the ability to distinguish vocal sounds correlates with our previous work showing substantial refinement of axonal connectivity in cortico-basal ganglia pathways necessary for vocal learning.
Auditory Category Perception as a Natural Cognitive Activity in Songbirds
Christopher B. Sturdy,Laurie L. Bloomfield,Tara M. Farrell,Marc T. Avey
Comparative Cognition & Behavior Reviews , 2007,
Abstract: The authors summarize progress in research on how songbirds (oscines) categorize the acoustic communication of conspecifics. They found that category perception for the learned songs and calls of oscines are well described by four principles: The exemplars from a single vocal category are discriminated one from another. Exemplars of different vocal categories are more easily discriminated than exemplars of the same category. Vocal categorization transfers to novel exemplars. Lastly, the labels applied to sets of vocal exemplars are descriptive of the natural categories an oscine species uses to classify exemplars. The authors use bioacoustic data to generate statistical predictions about the importance of vocal features; field and laboratory tests confirm the importance of those features. In comparisons between the study of visual and auditory categorization tasks, the authors suggest that auditory tasks are more useful because (i) human photography and its reproduction are a poor match for avian visual systems, and (ii) real-world experience with conspecific vocalizations impacts auditory classification in later operant discriminations. Finally, the authors consider the enmeshing of prototypes and exemplars in the representation of learned vocalizations and conclude that evolution provides prototypes used in species recognition and that experience provides exemplars used to recognize individual conspecifics.
Spike timing and the coding of naturalistic sounds in a central auditory area of songbirds  [PDF]
Brian D. Wright,Kamal Sen,William Bialek,Allison J. Doupe
Physics , 2002,
Abstract: In nature, animals encounter high dimensional sensory stimuli that have complex statistical and dynamical structure. Attempts to study the neural coding of these natural signals face challenges both in the selection of the signal ensemble and in the analysis of the resulting neural responses. For zebra finches, naturalistic stimuli can be defined as sounds that they encounter in a colony of conspecific birds. We assembled an ensemble of these sounds by recording groups of 10-40 zebra finches, and then analyzed the response of single neurons in the songbird central auditory area (field L) to continuous playback of long segments from this ensemble. Following methods developed in the fly visual system, we measured the information that spike trains provide about the acoustic stimulus without any assumptions about which features of the stimulus are relevant. Preliminary results indicate that large amounts of information are carried by spike timing, with roughly half of the information accessible only at time resolutions better than 10 ms; additional information is still being revealed as time resolution is improved to 2 ms. Information can be decomposed into that carried by the locking of individual spikes to the stimulus (or modulations of spike rate) vs. that carried by timing in spike patterns. Initial results show that in field L, temporal patterns give at least ~20% extra information. Thus, single central auditory neurons can provide an informative representation of naturalistic sounds, in which spike timing may play a significant role.
Representation of Early Sensory Experience in the Adult Auditory Midbrain: Implications for Vocal Learning  [PDF]
Anne van der Kant, Sébastien Derégnaucourt, Manfred Gahr, Annemie Van der Linden, Colline Poirier
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0061764
Abstract: Vocal learning in songbirds and humans occurs by imitation of adult vocalizations. In both groups, vocal learning includes a perceptual phase during which juveniles birds and infants memorize adult vocalizations. Despite intensive research, the neural mechanisms supporting this auditory memory are still poorly understood. The present functional MRI study demonstrates that in adult zebra finches, the right auditory midbrain nucleus responds selectively to the copied vocalizations. The selective signal is distinct from selectivity for the bird's own song and does not simply reflect acoustic differences between the stimuli. Furthermore, the amplitude of the selective signal is positively correlated with the strength of vocal learning, measured by the amount of song that experimental birds copied from the adult model. These results indicate that early sensory experience can generate a long-lasting memory trace in the auditory midbrain of songbirds that may support song learning.
Song exposure regulates known and novel microRNAs in the zebra finch auditory forebrain
Preethi H Gunaratne, Ya-Chi Lin, Ashley L Benham, Jenny Drnevich, Cristian Coarfa, Jayantha B Tennakoon, Chad J Creighton, Jong H Kim, Aleksandar Milosavljevic, Michael Watson, Sam Griffiths-Jones, David F Clayton
BMC Genomics , 2011, DOI: 10.1186/1471-2164-12-277
Abstract: In the auditory forebrain, we identified 121 known miRNAs conserved in other vertebrates. We also identified 34 novel miRNAs that do not align to human or chicken genomes. Five conserved miRNAs showed significant and consistent changes in copy number after song exposure across three biological replications of the song-silence comparison, with two increasing (tgu-miR-25, tgu-miR-192) and three decreasing (tgu-miR-92, tgu-miR-124, tgu-miR-129-5p). We also detected a locus on the Z sex chromosome that produces three different novel miRNAs, with supporting evidence from Northern blot and TaqMan qPCR assays for differential expression in males and females and in response to song playbacks. One of these, tgu-miR-2954-3p, is predicted (by TargetScan) to regulate eight song-responsive mRNAs that all have functions in cellular proliferation and neuronal differentiation.The experience of hearing another bird singing alters the profile of miRNAs in the auditory forebrain of zebra finches. The response involves both known conserved miRNAs and novel miRNAs described so far only in the zebra finch, including a novel sex-linked, song-responsive miRNA. These results indicate that miRNAs are likely to contribute to the unique behavioural biology of learned song communication in songbirds.Songbirds are important models for exploring the neural and genomic mechanisms underlying vocal communication, social experience and learning (reviewed in [1]). Songbirds communicate using both innate calls and learned vocalizations (songs), and unique specializations of the brain evolved to support this behavior (reviewed in [2]). In the zebra finch, only the male produces songs, although both sexes process and discriminate specific songs [3-6]. The genome is actively engaged by song communication, as first shown in an early demonstration of how gene responses in the brain discriminate among different song stimuli [7]. The genomic response is not a simple correlate of neural activity and it can var
Growing season precipitation in Finland under recent and projected climate
J. S. Ylh isi, H. Tiet v inen, P. Peltonen-Sainio, A. Ven l inen, J. Eklund, J. R is nen,K. Jylh
Natural Hazards and Earth System Sciences (NHESS) & Discussions (NHESSD) , 2010,
Abstract: The past and projected future precipitation sum in May–September for two areas in Finland, one located in the south-west (SW) and the other in the north-east (NE), is studied using 13 regional climate simulations and three observational datasets. The conditions in the present-day climate for agricultural crop production are far more favourable in the south-western part of the country than the more continental north-eastern Finland. Based on a new high-resolution observational precipitation dataset for Finland (FMI_grid), with a resolution of 10×10 km, the only statistically significant past long-term (1908–2008) precipitation tendencies in the two study regions are positive. Differences between FMI_grid and two other observational datasets during 1961–2000 are rather large in the NE, whereas in the SW the datasets agree better. Observational uncertainties stem from the interpolation and sampling errors. The projected increases in precipitation in the early stage of the growing season would be most favourable for agricultural productivity, but the projected increases in August and September might be harmful. Model projections for the future indicate a statistically significant increase in precipitation for most of the growing season by 2100, but the distribution of precipitation within the growing season is not necessarily the most optimal.
Morphogenesis underlying the development of the everted teleost telencephalon  [cached]
Folgueira Mónica,Bayley Philippa,Navratilova Pavla,Becker Thomas S
Neural Development , 2012, DOI: 10.1186/1749-8104-7-32
Abstract: Background Although the mechanisms underlying brain patterning and regionalization are very much conserved, the morphology of different brain regions is extraordinarily variable across vertebrate phylogeny. This is especially manifest in the telencephalon, where the most dramatic variation is seen between ray-finned fish, which have an everted telencephalon, and all other vertebrates, which have an evaginated telencephalon. The mechanisms that generate these distinct morphologies are not well understood. Results Here we study the morphogenesis of the zebrafish telencephalon from 12 hours post fertilization (hpf) to 5 days post fertilization (dpf) by analyzing forebrain ventricle formation, evolving patterns of gene and transgene expression, neuronal organization, and fate mapping. Our results highlight two key events in telencephalon morphogenesis. First, the formation of a deep ventricular recess between telencephalon and diencephalon, the anterior intraencephalic sulcus (AIS), effectively creates a posterior ventricular wall to the telencephalic lobes. This process displaces the most posterior neuroepithelial territory of the telencephalon laterally. Second, as telencephalic growth and neurogenesis proceed between days 2 and 5 of development, the pallial region of the posterior ventricular wall of the telencephalon bulges into the dorsal aspect of the AIS. This brings the ventricular zone (VZ) into close apposition with the roof of the AIS to generate a narrow ventricular space and the thin tela choroidea (tc). As the pallial VZ expands, the tc also expands over the upper surface of the telencephalon. During this period, the major axis of growth and extension of the pallial VZ is along the anteroposterior axis. This second step effectively generates an everted telencephalon by 5 dpf. Conclusion Our description of telencephalic morphogenesis challenges the conventional model that eversion is simply due to a laterally directed outfolding of the telencephalic neuroepithelium. This may have significant bearing on understanding the eventual organization of the adult fish telencephalon.
No small feat: microRNA responses during vocal communication in songbirds
Claudio V Mello, Peter V Lovell
BMC Biology , 2011, DOI: 10.1186/1741-7007-9-35
Abstract: See research article:http://www.biomedcentral.com/1471-2164/12/277 webciteImmersed in a vast ocean of sounds our brains seek to process and memorize only those sounds that are most relevant to us. Thus, we tend to pay a lot of attention to vocal signals produced by other members of our own species, particularly those that convey information critical to social interaction, reproduction and survival. We are talking, of course, about the sounds that comprise speech and language. Remarkably, only a few animals communicate through a system of vocalizations with characteristics that resemble the complexities and capabilities of human speech. Songbirds (more technically, Passeriformes oscines) represent one such group. They not only communicate through complex vocal signals (songs), but also like humans they learn them through vocal imitation [1]. In many respects this capability mirrors the acquisition of speech in humans, and has made songbirds an exquisite model organism for unraveling the neuronal basis of vocal and speech learning ([2] and references therein). Among the numerous basic insights contributed by songbird research is the demonstration that complex gene networks are rapidly regulated in the brain when songbirds hear song or engage in singing [2]. Microarray studies, in particular, have revealed that song exposure influences the expression of hundreds of genes in the auditory forebrain of the zebra finch, Taeniopygia guttata ([3] and Lovell and Mello, unpublished observations) (Figure 1). Chief among these, the activity-regulated immediate early genes (IEGs) zenk (also known as zif-268, egr-1 or ngfi-a), fos, jun and arc suggest a dynamic link between the perceptual processing and memorization of birdsong, and underlying transcriptional networks that regulate properties of brain circuits [4,5]. Now, a study by Gunaratne et al. [6] extends these findings, revealing that microRNAs (miRNAs), a class of small non-coding RNAs that may serve as control points in t
Estradiol differentially affects auditory recognition and learning according to photoperiodic state in the adult male songbird, European starling (Sturnus vulgaris)  [PDF]
Rebecca M. Calisi,Daniel P. Knudsen,Jesse S. Krause,John C. Wingfield,Timothy Q. Gentner
PeerJ , 2015, DOI: 10.7717/peerj.150
Abstract: Changes in hormones can affect many types of learning in vertebrates. Adults experience fluctuations in a multitude of hormones over a temporal scale, from local, rapid action to more long-term, seasonal changes. Endocrine changes during development can affect behavioral outcomes in adulthood, but how learning is affected in adults by hormone fluctuations experienced during adulthood is less understood. Previous reports have implicated the sex steroid hormone estradiol (E2) in both male and female vertebrate cognitive functioning. Here, we examined the effects of E2 on auditory recognition and learning in male European starlings (Sturnus vulgaris). European starlings are photoperiodic, seasonally breeding songbirds that undergo different periods of reproductive activity according to annual changes in day length. We simulated these reproductive periods, specifically 1. photosensitivity, 2. photostimulation, and 3. photorefractoriness in captive birds by altering day length. During each period, we manipulated circulating E2 and examined multiple measures of learning. To manipulate circulating E2, we used subcutaneous implants containing either 17-β E2 and/or fadrozole (FAD), a highly specific aromatase inhibitor that suppresses E2 production in the body and the brain, and measured the latency for birds to learn and respond to short, male conspecific song segments (motifs). We report that photostimulated birds given E2 had higher response rates and responded with better accuracy than those given saline controls or FAD. Conversely, photosensitive, animals treated with E2 responded with less accuracy than those given FAD. These results demonstrate how circulating E2 and photoperiod can interact to shape auditory recognition and learning in adults, driving it in opposite directions in different states.
Localized Brain Activation Related to the Strength of Auditory Learning in a Parrot  [PDF]
Hiroko Eda-Fujiwara, Takuya Imagawa, Masanori Matsushita, Yasushi Matsuda, Hiro-Aki Takeuchi, Ryohei Satoh, Aiko Watanabe, Matthijs A. Zandbergen, Kazuchika Manabe, Takashi Kawashima, Johan J. Bolhuis
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0038803
Abstract: Parrots and songbirds learn their vocalizations from a conspecific tutor, much like human infants acquire spoken language. Parrots can learn human words and it has been suggested that they can use them to communicate with humans. The caudomedial pallium in the parrot brain is homologous with that of songbirds, and analogous to the human auditory association cortex, involved in speech processing. Here we investigated neuronal activation, measured as expression of the protein product of the immediate early gene ZENK, in relation to auditory learning in the budgerigar (Melopsittacus undulatus), a parrot. Budgerigar males successfully learned to discriminate two Japanese words spoken by another male conspecific. Re-exposure to the two discriminanda led to increased neuronal activation in the caudomedial pallium, but not in the hippocampus, compared to untrained birds that were exposed to the same words, or were not exposed to words. Neuronal activation in the caudomedial pallium of the experimental birds was correlated significantly and positively with the percentage of correct responses in the discrimination task. These results suggest that in a parrot, the caudomedial pallium is involved in auditory learning. Thus, in parrots, songbirds and humans, analogous brain regions may contain the neural substrate for auditory learning and memory.
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