From the stunning aerial displays of large bird flocks to the collective coordination of human culture, how do the interactions among individuals give rise to such interesting and emergent group behavior, and how are these interactions constructed and controlled within the brain and the body? While collective animal behavior has long fascinated and engaged scientists across disciplines, quantitative studies in three-dimensional environments in which animals naturally live are rare and phenomenological descriptions of collective interactions, on which many models are based, have not previously been connected with their foundation in biological circuits. Here, we propose a novel, cross-disciplinary effort to measure and model the three-dimensional collective dynamics of shoaling in the zebrafish (Danio rerio) and to use genetic, pharmacological and neural perturbations to connect these dynamics to underlying biological mechanisms. We will combine expertise in zebrafish genetics and biology with precision 3D motion tracking and theoretical ideas drawn from statistical physics to quantify and elucidate the interactions that drive such collective motion. We will design a custom apparatus consisting of multiple, fast cameras and image-processing software to capture, with high-resolution in space and time, the simultaneous dynamics of interacting fish in a fully three-dimensional arena. Using this apparatus and leveraging the power of the zebrafish model system, we will quantify the collective dynamics of wild-type shoals and compare them to shoals from zebrafish deficient in their visual and lateral line sensory systems. We will also analyze shoals with disruptions to social neural circuits in the brain, focusing in particular on oxytocin and dopaminergic signaling, using optogenetic imaging. Exploiting this rich abundance of shoaling trajectory data, we will construct maximum entropy and agent-based models of group dynamics, and we will use the parameterization of these models to quantitatively characterize the collective shoaling state and changes of this state between conditions. While shoaling is the focused target of our initial efforts, zebrafish exhibit a variety of social behaviors that can also be studied with our proposed capabilities, both computational and experimental.

The cross-talk between integrin-based adhesions to the extracellular matrix and dynamic microtubules plays a crucial role in cell polarity and migration. Integrin-based adhesions can promote cortical microtubule stabilization in their vicinity. In turn, microtubules can strongly affect the formation and turnover of the adhesion sites. However, the molecular basis of these connections remains enigmatic.
Here, we propose to decipher the molecular chain of events induced by mechanotransduction at integrin adhesions that leads to cortical microtubule stabilization and analyze the morphogenetic impact of this process. To achieve this goal, we will bring together four distinct sets of expertise: cell biology of the cytoskeleton (Akhmanova); structural biology, biochemistry and biophysics of protein-protein interactions (Goult); mechanobiology and single molecule analysis of force dependence of protein-protein interactions (Yan) and genetic analysis of morphogenesis in flies (Tanentzapf).
We will use advanced cell manipulation assays to directly test whether mechanotransduction at adhesions affects microtubule capture and stabilization at the adjacent cortical sites. To uncover the molecular basis of this process, we will focus on a recently discovered connection between a cortical adaptor protein, which constitutes a part of the microtubule stabilization complex, and an adhesion component. At the same time, we will perform experiments, which will allow us to identify and explore additional links between focal adhesions and the microtubule-stabilizing complex, and thus generate a comprehensive functional map of these connections. Given that the investigated proteins are highly conserved, we will combine genetics, imaging and modeling to address their impact on morphogenesis and tissue maintenance in flies. Our work will shed light on how cellular mechanics and cytoskeletal dynamics are integrated at the molecular level.

Cells in developing organisms can keep track of time. They use this to make important decisions - for example on when to turn or to stop in the case of migrating axons or cells - without being instructed to do so by signals from other cells in their surroundings. But how such internal clocks work, and importantly, how they are made to be so precise, is still largely unknown. Previous work by one of the participating teams has shown that during the development of the nematode worm C. elegans, the migration of a neuroblast is regulated through the timed expression of a signaling receptor. This system provides a powerful assay to study at single cell level how an internal clock controls gene expression. The three teams will use a unique combination of genetics, evolutionary biology and mathematical modeling to gain detailed insight into the workings of this timing mechanism. They will investigate how timing is mediated at the transcriptional level, how robust this is to environmental variations and how this mechanism has evolved in other nematode species. Importantly, these results will be used in mathematical modeling to gain insight into the underlying regulatory architecture and to make predictions that will be tested in further experiments. Such interplay between experimental and theoretical analysis is a powerful and innovative approach that will enable the three teams to gain deep understanding of how cells measure time.

Vocal learning is a fundamental trait of spoken language and yet the neuro-molecular mechanisms underpinning this trait are poorly understood. The capacity for vocal learning has only been identified in a handful of non-human mammals; cetaceans, elephants and bats. The first evidence for some vocal adaptations in non-human primates is only now emerging. Despite intense interest, these limited experimental options mean that the neural underpinning of mammalian vocal learning has been massively understudied. Some birds, such as parrots, hummingbirds and songbirds, are also vocal learners. Work in songbirds has provided valuable insights, but the evolutionary divergence of avian brain structure is a barrier for direct extrapolation to mammals. Furthermore the lack of a mammalian animal model means that it is unclear whether or not mammals and birds use similar mechanisms during vocal learning. As a result, fundamental questions in the field remain unanswered, such as: how is vocal learning encoded in the mammalian brain, how do neurological and genetic substrates contribute to this trait, and are these mechanisms similar across divergent species?
We will establish bats as an ideal model system because they are mammals that have robustly shown vocal learning and have remarkable capacity for combining vocal phonemes to create new types of vocalisations. Bats can be maintained in laboratory colonies, and there is already a wealth of information regarding the neuroethological mechanisms by which they produce and perceive their vocalizations. We aim to establish bats as the first mammalian model of vocal learning by designing innovative communication paradigms coupled to comprehensive neurological and genetic interrogations. This proposal integrates psychophysical, anatomical, electrophysiological & genetic research in an innovative way to begin to address the encoding of vocal learning in the mammalian brain.
This complementary and coordinated research effort, focuses on a tractable and very promising animal model, addresses a fundamental gap in the field and is likely to significantly advance our knowledge about the origins of vocal learning and ultimately human speech. We believe that this work will have important repercussions across sensory ecology, neuroscience, genetics, evolutionary biology and linguistics.

Like human babies learning speech, young songbirds learn to produce song by imitating adults. Both babies and young birds need to listen to adult vocalizations, extract the relevant information and store it in the brain and then improve their own ‘babbling’ sounds step by step towards the adult version. Experiments on vocal learning have focused mainly on sounds, although sight also seems to play an important role. Babies of only 8 weeks of age already associate speech sounds with the correct mouth position required to make that sound. Moreover, people report that they hear the syllable ‘ga’ when in fact a loudspeaker plays ‘pa’ while a video screen shows the face of a speaker mouthing ‘ka’. This perceptual phenomenon is known as the ‘McGurk' effect. It reveals that sensory information from the ear and eye are integrated in the brain to form a combined, multimodal percept.
Like human speech, birdsong can be heard and seen. Young birds see their fathers moving their beaks while hearing their song. There is substantial evidence to assume that the combined exposure to acoustic and visual cues enhances song learning not only in human but also in bird babies. We aim to uncover the role of this multimodal perception and its underlying neural architecture in vocal learning. Focusing on the zebra finch, the prevalent animal model for molecular, neural and developmental aspects of human speech we will adopt a robotic approach that allows full experimental control over auditory and visual cues.
Simultaneously recording acoustic and visual cues of singing adult birds, we will analyze synchrony between different song elements and the opening and closing of a bird's beak. We will use this to develop a robotic zebra finch that allows us to create matched and mismatched multimodal stimuli. Juvenile birds will be raised with various tutoring regimes to assess the relative roles of unimodal versus multimodal cues, life versus robot cues, and matched versus mismatched cues. Upon reaching adulthood, tutored birds will be tested on their song copy performance (males only), song preference (females only), or discrimination ability (all birds). Finally, we will use a subset of tutored birds to study underlying neural processes by using molecular tools that allow us to pinpoint where in the brain multimodal information is processed and how this is linked to vocal learning.

Like human babies learning speech, young songbirds learn to produce song by imitating adults. Both babies and young birds need to listen to adult vocalizations, extract the relevant information and store it in the brain and then improve their own ‘babbling’ sounds step by step towards the adult version. Experiments on vocal learning have focused mainly on sounds, although sight also seems to play an important role. Babies of only 8 weeks of age already associate speech sounds with the correct mouth position required to make that sound. Moreover, people report that they hear the syllable ‘ga’ when in fact a loudspeaker plays ‘pa’ while a video screen shows the face of a speaker mouthing ‘ka’. This perceptual phenomenon is known as the ‘McGurk' effect. It reveals that sensory information from the ear and eye are integrated in the brain to form a combined, multimodal percept.
Like human speech, birdsong can be heard and seen. Young birds see their fathers moving their beaks while hearing their song. There is substantial evidence to assume that the combined exposure to acoustic and visual cues enhances song learning not only in human but also in bird babies. We aim to uncover the role of this multimodal perception and its underlying neural architecture in vocal learning. Focusing on the zebra finch, the prevalent animal model for molecular, neural and developmental aspects of human speech we will adopt a robotic approach that allows full experimental control over auditory and visual cues.
Simultaneously recording acoustic and visual cues of singing adult birds, we will analyze synchrony between different song elements and the opening and closing of a bird's beak. We will use this to develop a robotic zebra finch that allows us to create matched and mismatched multimodal stimuli. Juvenile birds will be raised with various tutoring regimes to assess the relative roles of unimodal versus multimodal cues, life versus robot cues, and matched versus mismatched cues. Upon reaching adulthood, tutored birds will be tested on their song copy performance (males only), song preference (females only), or discrimination ability (all birds). Finally, we will use a subset of tutored birds to study underlying neural processes by using molecular tools that allow us to pinpoint where in the brain multimodal information is processed and how this is linked to vocal learning.

Throughout evolution, the human genome has been attacked by retrotransposons, parasitic DNA elements that spread through our genome by a copy-paste activity. I previously showed that SVA elements, the youngest class of retrotransposons in our genome, harbour a strong gene-regulatory potential, which is normally repressed by KRAB zinc finger protein ZNF91 (Jacobs et al., 2014, Nature). However, for reasons unknown, repression of retrotransposons is much less efficient in neurons, resulting in the activation of the hidden enhancer potential of SVA elements spread throughout the human genome. The importance of these SVA insertions for the evolution of human neural gene-regulatory networks, and how many genes have come to depend on SVA's regulatory influence, remains elusive. This research program uses 'cortical organoids’; 3-dimensional brain tissues derived from human and primate stem cells, to investigate how recent SVA insertions have impacted human neuronal gene expression. Furthermore, I will investigate how changes of the epigenetic landscape in neurons affect the activity of retrotransposons and the influence they have on nearby neural genes. Finally, I will explore the possibility that loss of epigenetic silencing of retrotransposons is responsible for dysregulation of genes associated with neurological diseases. Preliminary findings suggest a potential role for retrotransposons in susceptibility loci for Alzheimer's and Parkinson's disease. Finding further support for this notion in the current research program, will form the basis of a novel concept that can explain how changes in the epigenetic landscape can uncover a dormant genetic predisposition to disease.