BRAIN Initiative: Development and Validation of Novel Tools to Probe Cell-Specific and Circuit-Specific Processes in the Brain (R01 Clinical Trial Not Allowed)

RFA-MH-26-170

This Notices of Funding Opportunity (NOFO) is designed to support the development and validation of novel tools to facilitate the detailed analysis of cells and circuits and provide insights into the neural circuitry and structure underlying complex behaviors. The human brain consists of an estimated one hundred billion neurons and more than one trillion supporting glial cells that are uniquely organized to confer the extraordinary computational activities of the brain. Cell types are categorized by their anatomical position, neurotransmitter content, dendritic and axonal connections, receptor profile, gene expression profile, and distinct electrical properties. Although the human brain has long been the focus of numerous studies, with major achievements made along the way, many specific details about the brain remain to be discovered, such as cell types and connections that are responsible for rapid information processing. Defining cellular and circuit-level function is dependent on detailed knowledge about the components and structure of the circuit. Such knowledge, in turn, is fundamental to understanding how these features underlie cognition and behavior, which should aid in the development of targeted cell-type and circuit-specific therapeutics to treat brain disorders. Improved technology is needed to obtain this knowledge.

Development of novel tools that will delineate anatomical connections between cells and expand our knowledge of circuit architecture and function is an area well poised for additional investment. Several efforts are ongoing to study large-scale, long-range connections, such as the BRAIN Initiative Connectivity across Scales (BRAIN CONNECTS) program.  The recent development of new technologies (e.g., hydrogel-based brain tissue clearing, expansion microscopy, spatial transcriptomics, and several other imaging breakthroughs) allow an unprecedented three-dimensional view into the post-mortem brain. These exciting technologies hold promise for mapping short- and long-range connections throughout the brain. Coupled with improved activity monitoring technologies in awake, behaving animals, these new tools promise an understanding of circuitry in action. Further development of these technologies is crucial to push the envelope beyond our current capabilities. To this end, applicants from the biological sciences are encouraged to establish collaborations with nanobiologists, material scientists, engineers and colleagues in other disciplines to develop groundbreaking approaches to study brain activity.

This NOFO solicits applications to develop next-generation, innovative technologies to define and target specific cell types in the brain. Of particular interest are first-in-class and/or cross-cutting non-invasive or minimally invasive techniques that permit repeated measurements from cells over time in a non-destructive manner. Tools/technologies relevant for this initiative are expected to be transformative, either through the development of novel tools that may be high-risk or through major advances in current approaches that break through technical barriers and will significantly improve current capabilities. An emphasis of the BRAIN initiative is the development of novel tools to study the brain, and here we highlight the need for innovative approaches to bridge experimental scales. Studies that are able to explore molecular and cellular mechanisms of neural activity permitting improved precision and sensitivity in the analysis of micro-and macro-circuits are strongly encouraged. Progress in understanding how the activity of the brain translates to complex behaviors will be facilitated by non-invasive approaches for both monitoring and manipulating neural activity in awake, behaving organisms.

Priority Areas of Research

This NOFO seeks applications in areas including, but not limited to:

• Novel methods for tagging individual neurons such that cellular components of a functional circuit can be explored.
• Novel methods for non-invasive targeted access to, or manipulation of, distinct cell types in defined circuits with spatiotemporal control.
• Novel, transgenic methods in multiple model species to allow more refined cell-specific and circuit-specific manipulation.
• Novel technologies to target and characterize non-neuronal cells, including glial and vascular cells, in the brain.
• Novel methods for visualizing or manipulating epigenomic marks or gene expression in neural cells.
• Development of cell type-specific molecular sensors and additional tools and approaches to address circuit-specific manipulation and monitoring.
• New tools and approaches that minimize tissue and cell perturbations so that cell viability is maintained, allowing for multiple repeated measures in the same cell over time.
• Development of in situ gene profiling using FISH and sequencing methodologies.
• Unique combinations of tools for multiplex analysis and/or manipulation of single cells in situ to maximize data content over many parameters (e.g., RNAs, proteins, metabolites, organelles, electrochemical dynamics, signal secretion/reception/transduction, cytoarchitecture or migratory changes).
• Novel automated and scalable assays for high-throughput analysis of single cells in situ in the brain, including scalability of measured parameters in parallel, cell numbers and/or speed of processing.
• Technologies enabling phenotypic comparison of cell types across species and classes.
• Novel trans-synaptic tracers that can work in retrograde and anterograde direction or deliver cargos to cells in the nervous system.
• Novel trans-synaptic tracers that can be used both at the electron- and light-microscopy level.
• Novel tools or methods to label and identify chemical or electrical synaptic molecules and contacts.
• Innovative tools that provide significant advances in sensitivity, selectivity, or the spatiotemporal resolution of molecules/structures/activities within single cells in the brain and between ostensibly similar cells in situ (e.g., high-resolution imaging of molecular interactions within single cells).
• Enhanced temporal and spatial resolution techniques for noninvasive molecular imaging of neuronal cells for in situ brain studies.
• Novel uses of super-resolution light microscopic approaches for identifying synaptic connections and mapping micro-circuits.
• Innovative approaches to reduce the time and cost of determining high-resolution synaptic connectivity by electron microscopy or other approaches.
• Development of novel sensors or tools to manipulate neurotransmitters or neuromodulators release or intracellular molecules.
• Innovative ways to use multiple vectors to deliver “split” gene products to limit and/or control expression in specific cell types.
• Significantly improved viral- or non-viral-mediated gene delivery that targets specific cells or cell types in the nervous system.
• Novel methods (genetic or non-genetic) to deliver active agents (e.g., chemical or pharmacological probes/drugs) to specific neurons or intracellular compartments, and/or techniques to detect target engagement by those agents in intact brains in situ.
• Chemical or genetic engineering of blood brain barrier-crossing carrier agents (such as tagged antibodies or other tools) to allow delivery of specific cargoes (e.g., neuronal activity, effectors, tracers or sensors) to specific cells or circuits.
• Unique systems-level single cell computational approaches to help define functional cell types and circuitry.
• Novel computational approaches to analyze and integrate multi-scale datasets to better understand brain function.
• Innovative approaches to bridge scales of experimental approach. Studies that are able to explore molecular and cellular mechanisms of neural activity in broader contexts are encouraged.
• Novel techniques for integrating micro-scale connectivity data (e.g., by electron microscopy) with cellular or synaptic phenotypic information.
• Innovative molecular complementation methods to identify synaptic connections and determine their phenotypes.

Application budgets are not limited but need to reflect the actual needs of the proposed project.

30 days before application due date

February 07, 2025; October 07, 2025

Eunyoung Kim, Ph.D.
National Institute of Mental Health (NIMH)
Telephone: 301-827-3420
Email: eunyoung.kim@nih.gov