HNN U24 DISSEMINATION PROJECT SUMMARY The Human Neocortical Neurosolver (HNN) neural modeling tool was developed with BRAIN Initiative funding (R01EB022889: 09/2016–06/2020) to meet the Initiative’s goal to “develop innovative technologies to understand brain circuits and ensembles of circuits that inform understanding of the human brain and mechanisms for treating its disorder”. HNN is a biophysically principled neocortical circuit model with appropriate physics that allow bridging from macroscale human magneto- and electro-encephalography (M/EEG) signals to their cellular and circuit level generators. HNN is a hypothesis development and testing tool whose design and capabilities are unique compared to other M/EEG neural modeling software. A key value of HNN is to connect functionally- relevant human signals to circuit level dynamics studied in animal models, including data from revolutionary genetic and imaging tools used in mice and monkeys (e.g., Neuropixel recordings, calcium, and voltage imaging). These links are essential to discovering new principles of brain information processing and to developing treatments when this processing is disrupted by neuropathology. There is widespread use of M/EEG, and myriad inferences drawn from these signals about human brain function and health: HNN provides a highly accessible tool for researchers to make principled connections to the detailed neurons and circuits underlying these signals, to test new ideas and ground conclusions in circuit-level reality. The neuroscience community is actively engaged in the use of HNN for basic and clinical research, including studies of Alzheimer’s disease, autism spectrum disorder, pain, depression, and healthy development. While HNN was successfully developed, there remain several challenges for growth and long-term sustainability. The goal of this proposal is to support dissemination of HNN for broadly accessibly use and community-driven development. Identified challenges in maintenance of HNN’s code and documentation that ensure Findability, Accessibility, Interoperability, and Reusability will be addressed (Aim I), and key enhancements necessary to support end-user needs and experimental validation of model-derived predictions will be developed (Aim II). Interpreting the complex multiscale origin of M/EEG signals with HNN’s large-scale neural often requires domain expertise in computational neural modeling, human M/EEG, and neural dynamics. To support this need, we will continue to work with the community to integrate HNN into their projects through workshops, direct collaboration, and consultation with end-user groups, and by enabling HNN simulation on freely accessible supercomputers (Aim III). End-user feedback and documented support needs will be used to develop a Plan for Sustainability. A world-class Steering Committee includes developers of widely-adopted neuroscience software who will share their expertise to help HNN reach its maximal potential as translational neuroscience tool.

HNN DISSEMINATION NARRATIVE This project supports the continued dissemination of a software tool (Human Neocortical Neurosolver, HNN) that allows researchers to develop and test hypotheses on the cellular and circuit level origin of human magneto- and electro-encephalography. A key value of HNN is to connect functionally-relevant human signals to circuit level dynamics studied in animal models, including data from revolutionary genetic and imaging tools used in mice and monkeys. Insights gained from the dissemination tool will be helpful in understanding the underpinnings of neurological and psychiatric diseases, such as Alzheimer’s disease, pain, depression, autism and schizophrenia.