Project description:Similarities between speech and birdsong make songbirds advantageous for investigating the neurogenetics of learned vocal communication; a complex phenotype likely supported by ensembles of interacting genes in cortico-basal ganglia pathways of both species. To date, only FoxP2 has been identified as critical to both speech and birdsong. We performed weighted gene co-expression network analysis on microarray data from singing zebra finches to discover gene ensembles regulated during vocal behavior. We found ~2,000 singing- regulated genes comprising 3 co-expression groups unique to area X, the basal ganglia subregion dedicated to learned vocal-motor behavior. These contained known targets of human FOXP2 and potential avian targets. We validated novel biological pathways for vocalization. Our findings show that higher-order gene co-expression patterns, rather than expression levels, molecularly distinguish area X from the ventral striato-pallidum during singing. The previously unknown structure of singing-driven networks enables prioritization of molecular interactors that likely bear on human motor disorders, especially those affecting speech. Gene expression was measured in 2 basal ganglia sub-regions (area X & ventral striato-pallidum (VSP)) of 27 adult male zebra finches that sang different amounts of song over a 2hr period in the morning. 18 birds were allowed to sing freely, 9 birds were discouraged from singing by the presence of an investigator and those that sang fewer than 10 song motifs were considered “non-singers”.
Project description:Similarities between speech and birdsong make songbirds advantageous for investigating the neurogenetics of learned vocal communication; a complex phenotype likely supported by ensembles of interacting genes in cortico-basal ganglia pathways of both species. To date, only FoxP2 has been identified as critical to both speech and birdsong. We performed weighted gene co-expression network analysis on microarray data from singing zebra finches to discover gene ensembles regulated during vocal behavior. We found ~2,000 singing- regulated genes comprising 3 co-expression groups unique to area X, the basal ganglia subregion dedicated to learned vocal-motor behavior. These contained known targets of human FOXP2 and potential avian targets. We validated novel biological pathways for vocalization. Our findings show that higher-order gene co-expression patterns, rather than expression levels, molecularly distinguish area X from the ventral striato-pallidum during singing. The previously unknown structure of singing-driven networks enables prioritization of molecular interactors that likely bear on human motor disorders, especially those affecting speech.
Project description:Birdsong is powerful model for the neural mechanisms underlying motor skill learning. The success of this model is in part due to the experimental advantages of the song system, the anatomically and functionally discrete neural circuit dedicated to song. Despite a detailed understanding of the physiological and systems levels properties of this circuit, we still lack a comprehensive understanding of what cell types are present in each region of the song system and how these cell types compare to those found in the brains of other vertebrates. Here, we characterize the cellular repertoire of the song motor pathway using single-cell RNA-sequencing.
Project description:A defining feature of our species is the ability to manipulate our environment through the fine control of our hands and to communicate with others through the rapid and complex motor orchestration of human speech. The courtship song of songbirds shares a number of neural and behavioral similarities with human speech and other learned motor skills, providing a powerful model for understanding how enhanced motor skills develop at molecular and cellular levels. Birdsong is controlled by a specialized neural circuit whose properties enable high precision and speed. In particular, glutamatergic neurons in the birdsong motor region RA (Glut-RA) have higher spike rates and narrower action potentials than projection neurons in an adjacent motor region that does not control song, the dorsal intermediate arcopallium (Glut-AId). To identify candidate gene regulatory networks that establish the specialized properties of Glut-RA neurons, we performed single-nucleus profiling of gene expression and chromatin accessibility across song and non-song motor regions. We found that Glut-RA projection neurons and fast spiking interneurons (FSIs), a GABAergic type also characterized by high spike rates and narrow action potentials, share several transcriptional similarities. In particular, the transcription factor MAFB, which is essential for the development and fast-spiking physiology of FSIs in mice, is expressed in Glut-RA but no other projection neuron type. We found that MAFB transcription factor binding sites have enhanced chromatin accessibility specifically in glutamatergic neurons in RA relative to AId. Furthermore, gene regulatory network inference and in silico knockdown of MAFB expression reveal common MAFB targets in Glut-RA neurons and FSIs, and suggest that the transcription factor is necessary to specialize song Glut-RA neurons from non-song Glut-AId neurons. These data support a model in which birdsong projection neurons co-opt an interneuron gene regulatory program to enable the rapid physiological properties required for fast and precise birdsong performance.
Project description:When females mate promiscuously, female sperm storage provides scope to bias the fertilization success towards particular males via the non-random acceptance and utilization of sperm. The difficulties observing post-copulatory processes within the female reproductive tract mean that the mechanisms underlying cryptic female choice remain poorly understood. Here, we use zebra finches Taeniopygia guttata, selected for divergent sperm lengths, combined with a novel technique for isolating and extracting sperm from avian sperm storage tubules (SSTs), to test the hypothesis that sperm from separate ejaculates are stored differentially by female birds. We show that sperm from different inseminations enter different SSTs in the female reproductive tract, resulting in almost complete segregation of the sperm of competing males. We propose that non-random acceptance of sperm into SSTs, reflected in this case by sperm phenotype, provides a mechanism by which long sperm enjoy enhanced fertilization success in zebra finches.
Project description:A defining feature of our species is the ability to manipulate our environment through the fine control of our hands and to communicate with others through the rapid and complex motor orchestration of human speech. The courtship song of songbirds shares a number of neural and behavioral similarities with human speech and other learned motor skills, providing a powerful model for understanding how enhanced motor skills develop at molecular and cellular levels. Birdsong is controlled by a specialized neural circuit whose properties enable high precision and speed. In particular, glutamatergic neurons in the birdsong motor region RA (Glut-RA) have higher spike rates and narrower action potentials than projection neurons in an adjacent motor region that does not control song, the dorsal intermediate arcopallium (Glut-AId). To identify candidate gene regulatory networks that establish the specialized properties of Glut-RA neurons, we performed single-nucleus profiling of gene expression and chromatin accessibility across song and non-song motor regions. We found that Glut-RA projection neurons and fast spiking interneurons (FSIs), a GABAergic type also characterized by high spike rates and narrow action potentials, share several transcriptional similarities. In particular, the transcription factor MAFB, which is essential for the development and fast-spiking physiology of FSIs in mice, is expressed in Glut-RA but no other projection neuron type. We found that MAFB transcription factor binding sites have enhanced chromatin accessibility specifically in glutamatergic neurons in RA relative to AId. Furthermore, gene regulatory network inference and in silico knockdown of MAFB expression reveal common MAFB targets in Glut-RA neurons and FSIs, and suggest that the transcription factor is necessary to specialize song Glut-RA neurons from non-song Glut-AId neurons. These data support a model in which birdsong projection neurons co-opt an interneuron gene regulatory program to enable the rapid physiological properties required for fast and precise birdsong performance.
Project description:Fast moving animals depend on cues derived from the optic flow on their retina. Optic flow from translational locomotion includes information about the three-dimensional composition of the environment, while optic flow experienced during a rotational self motion does not. Thus, a saccadic gaze strategy that segregates rotations from translational movements during locomotion will facilitate extraction of spatial information from the visual input. We analysed whether birds use such a strategy by highspeed video recording zebra finches from two directions during an obstacle avoidance task. Each frame of the recording was examined to derive position and orientation of the beak in three-dimensional space. The data show that in all flights the head orientation was shifted in a saccadic fashion and was kept straight between saccades. Therefore, birds use a gaze strategy that actively stabilizes their gaze during translation to simplify optic flow based navigation. This is the first evidence of birds actively optimizing optic flow during flight.
Project description:Inbreeding depression, or the reduction in fitness due to mating between close relatives, is a key issue in biology today. Inbreeding negatively affects many fitness-related traits, including survival and reproductive success. Despite this, very few studies have quantified the effects of inbreeding on vertebrate gamete traits under controlled breeding conditions using a full-sib mating approach. Here, we provide comprehensive evidence for the negative effect of inbreeding on sperm traits in a bird, the zebra finch Taeniopygia guttata. We compared sperm characteristics of both inbred (pedigree F = 0.25) and outbred (pedigree F = 0) individuals from two captive populations, one domesticated and one recently wild-derived, raised under standardized conditions. As normal spermatozoa morphology did not differ consistently between inbred and outbred individuals, our study confirms the hypothesis that sperm morphology is not particularly susceptible to inbreeding depression. Inbreeding did, however, lead to significantly lower sperm motility and a substantially higher percentage of abnormal spermatozoa in ejaculate. These results were consistent across both study populations, confirming the generality and reliability of our findings.