Cellular profiling of a recently-evolved social behavior [snRNA-seq]
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ABSTRACT: Social behaviors are essential for survival and reproduction and vary strongly among individuals, species, and heritable brain diseases. The molecular and cellular bases of this variation are poorly resolved, and discovering them is necessary to understand how neural circuit and behavioral functions—and dysfunctions—vary in social contexts. Here we integrate single nucleus RNA-sequencing (snRNA-seq) with comparative genomics and automated behavior analysis to investigate the neurobiology of castle-building, a recently-evolved social, spatial, goal-directed, and repetitive construction behavior in Lake Malawi cichlid fishes. We simultaneously control for and analyze two biological variables correlated with castle-building behavior: quivering, a courtship “dance” behavior, and relative gonadal mass. We find signatures of building-, quivering-, and gonadal-associated neuronal excitation, gene expression, and neurogenesis in distinct cell populations. Converging lines of evidence support the involvement of estrogen, TrkB, and CCK signaling systems, and specific pallial excitatory neuronal subpopulations, in castle-building behavior. We show additional evidence that castle-building has evolved in part through genomic divergence in a gene module that is selectively expressed in stem-like quiescent radial glial cells (RGCs) lining the ventricular zone of the pallium. This RGC subpopulation exhibits signatures of a building-associated departure from quiescence, which in turn is associated with neuronal rebalancing in the putative fish homologue of the hippocampus. Our work supports an unexpected role for glia and neurogenesis in the evolution of social behavior, and more broadly shows how snRNA-seq can be used to systematically profile the cellular bases of previously unstudied social behaviors in new species systems.
Project description:Social behaviors are essential for survival and reproduction and vary strongly among individuals, species, and heritable brain diseases. The molecular and cellular bases of this variation are poorly resolved, and discovering them is necessary to understand how neural circuit and behavioral functions—and dysfunctions—vary in social contexts. Here we integrate single nucleus RNA-sequencing (snRNA-seq) with comparative genomics and automated behavior analysis to investigate the neurobiology of castle-building, a recently-evolved social, spatial, goal-directed, and repetitive construction behavior in Lake Malawi cichlid fishes. We simultaneously control for and analyze two biological variables correlated with castle-building behavior: quivering, a courtship “dance” behavior, and relative gonadal mass. We find signatures of building-, quivering-, and gonadal-associated neuronal excitation, gene expression, and neurogenesis in distinct cell populations. Converging lines of evidence support the involvement of estrogen, TrkB, and CCK signaling systems, and specific pallial excitatory neuronal subpopulations, in castle-building behavior. We show additional evidence that castle-building has evolved in part through genomic divergence in a gene module that is selectively expressed in stem-like quiescent radial glial cells (RGCs) lining the ventricular zone of the pallium. This RGC subpopulation exhibits signatures of a building-associated departure from quiescence, which in turn is associated with neuronal rebalancing in the putative fish homologue of the hippocampus. Our work supports an unexpected role for glia and neurogenesis in the evolution of social behavior, and more broadly shows how snRNA-seq can be used to systematically profile the cellular bases of previously unstudied social behaviors in new species systems.
Project description:Most behaviors are associated with heritable genetic variation. Genetic mapping has revealed genomic regions or, in a few cases, specific genes explaining part of this variation. However, understanding how genetic divergence shapes behavioral evolution remains unclear. Here we analyze the evolution of an innate extended phenotype: bower building among male cichlid fish of Lake Malawi, which build bowers of two types, pits and castles. F1 hybrids of pit-digging and castle-building species perform sequential construction of first pit and then castle bowers. Analysis of brain gene expression in these hybrids showed that genes near behavior-associated variants display behavior-dependent allele-specific expression with preferential expression of the pit-species allele during pit digging, and of the castle-species allele during castle building. These genes are highly enriched for functions and pathways involved in neurodevelopment and neural plasticity. Our results suggest that natural behaviors can be associated with complex genetic architectures that alter behavior via cis-regulatory differences whose effects on gene expression are specific to the behavior itself.
Project description:Spiny projection neurons (SPNs) of the striatum are critical in integrating neurochemical information to coordinate motor and reward-based behavior. Mutations in the regulatory transcription factors expressed in SPNs can result in neurodevelopmental disorders (NDDs). Paralogous transcription factorsFoxp1andFoxp2, which are both expressed in the dopamine receptor 1 (D1) expressing SPNs, are known to have variants implicated in NDDs. Utilizing mice with a D1-SPN specific loss ofFoxp1,Foxp2, or both and a combination of behavior, electrophysiology, and single-nuclei RNA (snRNA-seq) and single-nuclei Assay for Transposase-Accessible Chromatin sequencing (snATAC-seq), we find that loss of both genes results in impaired motor and social behavior as well as increased firing of the D1-SPNs. Differential gene expression analysis of snRNA-seq data implicates genes involved in autism risk, altered electrophysiological properties, and neuronal development and function. These data indicate complementary roles betweenFoxp1andFoxp2in the D1-SPNs.
Project description:Spiny projection neurons (SPNs) of the striatum are critical in integrating neurochemical information to coordinate motor and reward-based behavior. Mutations in the regulatory transcription factors expressed in SPNs can result in neurodevelopmental disorders (NDDs). Paralogous transcription factorsFoxp1andFoxp2, which are both expressed in the dopamine receptor 1 (D1) expressing SPNs, are known to have variants implicated in NDDs. Utilizing mice with a D1-SPN specific loss ofFoxp1,Foxp2, or both and a combination of behavior, electrophysiology, and single-nuclei RNA (snRNA-seq) and single-nuclei Assay for Transposase-Accessible Chromatin sequencing (snATAC-seq), we find that loss of both genes results in impaired motor and social behavior as well as increased firing of the D1-SPNs. Differential gene expression analysis of snRNA-seq data implicates genes involved in autism risk, altered electrophysiological properties, and neuronal development and function. These data indicate complementary roles betweenFoxp1andFoxp2in the D1-SPNs.
Project description:One great challenge in neuroscience is connecting molecular and cellular phenotypes to behavioral consequences. Using social motivation as a test case, we propose that individual behavioral trait variation can be leveraged to identify novel components of social reward circuits in the brain. Specifically, we hypothesized that either proportion or molecular features of distinct neuron classes in the hypothalamus can predict individual differences in social motivation. To test this, we generated high-precision single-nucleus RNA-sequencing profiles of >120,000 neurons from the hypothalamus and adjacent thalamus from 36 mice assessed for social motivation, balancing across sex and an autism-associated mutation genotype. Analysis of IEG patterns revealed that PVN Agtr1a+ neurons negatively predict social behavior. Consistent with this, FDA-approved AGTR1A antagonists increase social orienting. Next, analyzing neuronal subtype proportions as predictors of social behavior, we identified multiple neuronal populations whose relative abundance correlated with individual differences in social reward-seeking, particularly the Nxph4+ neurons of the posterior and lateral hypothalamus. Subsequent chemogenetic inhibition of these suppressed multiple aspects of social motivation. This work establishes a proof-of-principle for a new approach using single-cellsingle cell genomics to identify neural substrates for behavior and identifies cellular determinants of social motivation, which suggest therapeutic avenues for disorders with social deficits.
Project description:Social behavioral changes are a hallmark of several neurodevelopmental and neuropsychiatric conditions, nevertheless the underlying neural substrates of such dysfunction remain poorly understood. Building evidence points to the prefrontal cortex (PFC) as one of the key brain regions that orchestrates social behavior. We used this concept with the aim to develop a translational rat model of social-circuit dysfunction, the chronic PFC activation model (CPA). Chemogenetic designer receptor hM3Dq was used to induce chronic activation of the PFC over 10 days, and the behavioral and electrophysiological signatures of prolonged PFC hyperactivity were evaluated. To test the sensitivity of this model to pharmacological interventions on longer timescales, and validate its translational potential, the rats were treated with our novel highly selective oxytocin receptor (OXTR) agonist RO6958375, which is not activating the related vasopressin V1a receptor. CPA rats showed reduced sociability in the three-chamber sociability test, and a concomitant decrease in neuronal excitability and synaptic transmission within the PFC as measured by electrophysiological recordings in acute slice preparation. Sub-chronic treatment with a low dose of the novel OXTR agonist following CPA interferes with the emergence of PFC circuit dysfunction, abnormal social behavior and specific transcriptomic changes. These results demonstrate that sustained PFC hyperactivity modifies circuit characteristics and social behaviors in ways that can be modulated by selective OXTR activation and that this model may be used to understand the circuit recruitment of prosocial therapies in drug discovery.