ABR: Forebrain social communication network in Danionella, a miniature transparent fish

About This Grant

Correct use and interpretation of communication signals between individuals can determine the consequences of aggressive interactions, including the potential to win a fight or to avoid unnecessary escalation of aggression resulting in physical injury. How does the brain allow individuals to actively control signaling behaviors appropriate to different social contexts? Danionella fishes are among the smallest adult vertebrates (fishes, amphibians, reptiles, birds, mammals) and are transparent throughout their lifetime. These qualities give unprecedented access to the entire brain, not yet possible in any other vertebrate. Leveraging Danionella’s relatively simple, highly stereotyped and readily measurable acoustic and postural displays produced only during aggression, the investigators of this project investigate how the adult vertebrate brain regulates communication during aggression. Cellular and molecular methods are used to identify neurons activated during aggressive interactions in brain regions (cerebral hemispheres, hypothalamus) that together are proposed to be comparable to a core aggression system in mammals. Artificial intelligence-based methods are used to quantify adult posture and movements during aggression. This approach provides a rigorous analytical framework with which to evaluate the behavioral effects of neuroimaging-guided, laser-induced disruptions to individual brain regions comprising the proposed core aggression circuit. The new model for behavioral neuroscience used in this project thus presents a unique opportunity for identifying and understanding brain networks activated in adults during social interactions and, more specifically, during aggression. The project also includes activities aimed at transferring knowledge via interactive public events, and to provide interdisciplinary training and education to individuals at different career stages. Understanding how forebrain neuronal networks (e.g., preoptic area, hypothalamus) control the output of downstream motor-patterning circuitry in the midbrain remains central to understanding how the brain enables individuals to select and sequence different patterns of behavior. Social communication behaviors in fishes are particularly tractable models for addressing this challenge. Their behaviors are often highly stereotyped, differ in a finite set of easily quantified features, and depend on precise patterns of neural activation. Recent studies effectively demonstrate that miniature, transparent species of Danionella fishes, which are among the smallest living adult vertebrates, provide particularly tractable models for uncovering principles of neuro-behavioral mechanisms applicable to all vertebrates. Unlike the closely-related zebrafish, which are neither naturally transparent nor miniature as adults, Danionella adults make robust acoustic and postural displays that are often closely linked in timing during aggressive interactions. Aim 1 of this proposal seeks to map a forebrain aggression network that is activated in Danionella during multimodal displays and identify its neurochemical phenotypes. Aim 2 involves use of laser ablations of select forebrain sites identified in Aim 1 to test the predictions of a model, informed by artificial intelligence-based quantitative analysis of acoustic, postural, and jaw extension displays, about the forebrain’s role in driving acoustic and postural behaviors. These aims offer unprecedented opportunities to establish Danionella as a model to guide brain-wide optical and genetic studies of neural circuits underlying adult vertebrate aggression. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.