Funded Awards

Transcranial magnetic stimulation (TMS) is a noninvasive technique used to study brain function and can be used to treat some brain disorders. Researchers use computational simulations of TMS electrical fields to gain a better understanding of how TMS affects the brain. Existing simulations, however, are inherently variable due to factors that impact the accuracy and precision of the technique, such as differences in experimental set-up and coil placement. Dr. Gomez proposes to use a novel computational framework to measure and address the uncertainty and variability of TMS electrical fields. The project will increase the fidelity and reliability of TMS simulations. The results will benefit researchers and clinicians by enabling more precise control of the technique and may help improve medical uses of TMS.

The mammalian brain has unique abilities to process various sensory inputs from the environment, based on efficient and complex brain network structures and dynamics. However, the precise connections between the brain’s intricate wiring and its rich network dynamics are unclear, as is our understanding of how the brain’s connectivity and dynamics relate to underlying neural coding principles. Leveraging the Allen Institute’s Mouse Brain Connectivity Atlas, Dr. Choi will explore these issues, ultimately aiming to help close the gap between brain biophysiology and neural coding principles, with a focus on predictive coding theory using data-driven mathematical models.

Typically, we experience the world as a continuous sequence of events; but when recalling memories, we remember segmented episodes. The hippocampus and prefrontal cortex (PFC) play a role in segmenting, linking, and retrieving memories of associated events, but the neural circuit mechanism of this process is not well understood. Dr. Jafarpour aims to use intracranial encephalography (iEEG) to identify the neural dynamics in the hippocampal-PFC circuit that support the encoding of sequences of words. By combining iEEG with advanced analytical techniques, natural language processing models, and research with patients with hippocampal lesions, this project will offer insights into the neural basis of speech encoding and memory formation. The work may inform the development of neural prosthetics for use by patients with memory impairments.

Working memory is crucial to many human functions, and a better understanding of its underlying mechanisms could improve our understanding of memory abnormalities in advanced age. Current hypotheses suggest that working memory is maintained by a hierarchy of interconnected cortical areas, but more work is needed to understand the unique role of each area. Dr. Resulaj aims to study visual working memory at the systems and cellular level in the mouse. Utilizing novel behavior assays, a laser scanning galvo system, and optogenetics, this work ultimately will develop a computational model of visual working memory in the mouse cortex.

Activity in the striatum is known to be linked to perceptual decision-making processes orchestrated by the cortex. Dr. Sun proposes to use genetically-encoded calcium indicators to examine cortex-wide activity patterns in mice performing perceptual decision tasks. This will be combined with wide-field calcium imaging in order to correlate behavior with changes in neural activity. The research will enhance our understanding of how activity in the cortico-striatal pathway supports decision-making.

Olfaction is an extremely important sensory modality across species, and it is one of the first to be disrupted in many neurodegenerative diseases. Dr. Doyle will conduct a full census of all cell types in the mouse olfactory bulb, to better understand information integration and processing in the olfactory system. This approach will utilize transcriptomic (single cell RNA-sequencing) and epigenomic (single nucleus methylome- and single nucleus ATAC-sequencing) data generated by members of the BRAIN Initiative Cell Census Network (BICCN). Overall, this will allow for a fuller understanding of the roles of cell diversity, regulatory elements, and transcription factors in the mouse olfactory system.

While it is known that proprioception plays an important role in movement, how the brain translates proprioceptive information into information for movement in the somatosensory cortex (S1) is poorly understood. Dr. Blum aims to study how active and passive movements of limbs elicit different responses from muscle spindles and Golgi tendon organs, especially as reflected in area 3a of S1. Using electrophysiological data, arm kinematic measurements, and EMGs in monkeys trained to perform an arm-reaching task, this research aims to model afferent proprioceptive signals and motor outputs in a neural network model. These results will improve our understand of the neural control of movement.

Optogenetics and chemo-optogenetics are emerging tools for neuroscience research, providing ways to modulate cell function with light. However, current limitations for these tools include limited ability to target cells deep in the brain, the relatively small effects they elicit, and safety concerns over long-term use. Dr. Lam proposes to develop new chemo-optogenetic tools to address these issues, based on the TRPA1 and TRPV1 receptor channels. Further, she will develop this technology for in vivo use, testing its utility in behavioral assays of zebrafish. The work will improve our ability to understand brain circuit function, and will create a platform for the discovery of other novel chemo-optogenetic approaches that mimic natural cell activity.

Various improvements are being considered to create next generation biophysical models of blood oxygenation and fMRI measurements in brain. Dr. Sencan plans to quantify spatial and temporal diversity in cortical metabolism in order to inform these scientific advancements. By measuring processes of cortical oxygenation, metabolic rate, and blood flow responses at microvascular scales, she aims to understand how these processes contribute to brain function and vary across age, region, and depth in the awake, mouse brain. To achieve these goals, she will use novel experimental techniques, related to faster, deeper, and more realistic imaging of oxygen concentration. This work may support better interpretation of clinical results derived through imaging technologies like fMRI.

The brain’s inferior colliculus is described to have a patch- or matrix-like “modular” anatomical organization, with various nuclei and distinct chemical boundaries. However, the functional implications of this organization are unknown. Dr. Lesicko’s experiments aim to determine whether this modularity underlies distinct streams of information processing in the inferior colliculus. Using a combination of two-photon calcium imaging, clustering analysis, optogenetics, and behavioral assays in mice performing a behavioral task, the work will examine distinctions in neural activity and mechanisms for auditory and somatosensory signaling in the inferior colliculus.

Brain-computer interfaces (BCI) show promising potential in treating symptoms of various brain diseases. A collaborative group at the University of California, San Diego, has developed a high-density array of microgrid electrodes that are thin, non-destructive, and sit lightly on the surface of the brain, for improved decoding and resolution of neural activity. This study will implement this technology to study cortical physiology and organization in the rat somatosensory cortex. Dr. Cleary aims to test the capabilities of these surface microgrids for discriminating cortical columns in the rat “barrel cortex,” representing innervation of the whiskers. He also will study how surface stimulation of the cortex affects neural activity in different layers of the cortex, initially in rats and subsequently in human neurosurgical patients. This work may improve BCI technology, providing additional treatment strategies for various brain diseases.

In an effort to improve our understanding of how synaptic plasticity contributes to social memory, Dr. Phillips aim to create a tool to modulate synaptic plasticity in specific circuits during behavior. Using advanced imaging techniques and various innovative biochemical assays, she plans to create a photo-activatable inhibitor of presynaptic plasticity and will use this tool to understand the circuitry of social memory. The researcher will develop constructs of a photo-activatable PKA inhibitor and screen the constructs using 2-photon fluorescence lifetime imaging in HeLa cells. The optimized inhibitor constructs will then be expressed in the dCA2-vCA1, vCA1-PL, and PL-dPAG projections in mice and used to block presynaptic plasticity during social learning in either aggressive or neutral contexts.  Successful development of these tools will enable investigation of neural circuitry to better our understanding of behavior and neuropsychiatric diseases.

Neurodevelopmental disorders can arise from impairments in sensory-dependent refinement or strengthening of synapses during postnatal brain development. However, treatment strategies focused on addressing such impairments lack an advanced understanding of the cellular and molecular mechanisms of this process. Building on prior results showing that expression of the gene Fn14 is driven by visual experience and encodes a receptor required for synaptic refinement, Dr. Cheadle aims to use slice electrophysiology and bioinformatics to study how microglia-to-neuron signaling is involved in refinement via examining the role of TWEAK, an Fn14 receptor ligand, in healthy and neurodevelopmentally-impaired mice. The results may offer insights into the development of treatments for neurodevelopmental disorders.

Hippocampal microcircuits include excitatory pyramidal cells, which integrate information and signal to downstream brain regions, and inhibitory interneurons, which function locally to regulate pyramidal cell activity. Circuit dysfunction in the ventral hippocampus (vHipp) has been associated with various brain disorders. Dr. Donegan will use techniques including mammalian GFP reconstitution across synaptic partners (mGRASP), fiber photometry, in vivo electrophysiology, and optogenetics, to test the hypothesis that different types of interneurons in the vHipp differentially regulate the function of ventral hippocampus pyramidal cells depending on their projection target. She will also test whether vHipp microcircuit anatomy and function are altered by chronic stress, shedding light on the potential link between circuit dysfunction in the hippocampus and brain disorders.

Brain-computer interfaces and neuroprosthetics have provided a significant benefit to patients with cervical spinal cord injuries. However, current technology is limited in its abilities to allow the user to control how much force is exerted by the prosthesis and to provide sensory feedback from the prosthetic hand. In a public-private collaboration with Blackrock Microsystems, Dr. Boninger and colleagues are looking to improve the dexterity of neuroprostheses by incorporating microstimulation of the somatosensory cortex. This stimulation could provide tactile feedback to the user and hopefully allow the user to better control the force applied. Ultimately, this approach will improve the dexterity and control of prosthetic limbs used by patients with spinal cord injuries.

Small, tightly-packed granule cells (GrCs) in the cerebellum have been associated with sensory and motor events, but their specific roles remain unclear due to their close packing.  Dr. Broussard aims to precisely record from and perturb GrCs and measure the resulting effects on neural firing patterns and activity in mice. The researcher will develop a spike-counting method for genetically encoded indicators by optimizing the kinetics of the calcium sensor GCaMP. After developing a cleared skull preparation to access the full posterior cerebellum in mice, the new indicator will be used to map the neocortical drivers of GrC activity across the cerebellum, and rodent behavioral tasks will be used to disambiguate sensory, motor and internal-state contributions to granule cell activity patterns. Better knowledge of GrCs activity will further our understanding of neural circuits that guide sensory processing and plays roles in neurological disorders.

To process information about the world, the nervous system must distinguish external stimuli from internally generated sensory stimuli, but the mechanisms underlying the cellular basis of internally generated sensation and movement are not well understood. Here, Dr. Suver plans to develop a small circuit model of this process using the antennae of the fruit fly as a model system. Using electrophysiological recordings, optogenetics, and immunohistochemistry, she will develop the neural circuits controlling and sensing antennal movement as a cellular model for studying principles of active sensing. The insights gained from a tractable genetic circuit model may improve understanding of active sensation, as well as how these mechanisms might fail in disease.

Evidence suggests that both spontaneous and learned behaviors engage activity in various regions of the cortex. However, for perceptual decision-making, more complex and demanding tasks involve decorrelated cortical activity as a more distributed, widespread process throughout the cortex. Dr. Pinto aims to understand this phenomenon, using cutting-edge technology to study how distributed cortical acitivity mediates complex decision-making and the mechanisms of task-induced changes in large-scale cortical dynamics. The research will utilize two-photon calcium imaging, virtual reality behavioral tasks, pharmacogenetics, optogenetics, and modelling, increasing our understanding of the neural basis of decision-making.

The ability to learn, think, and make decisions in complex environments is extremely important to critical life functions across species, but the neural correlates of external and internal representative states are largely unstudied. Recent studies suggest activity in the amygdala and orbitofrontal cortex correlate to state representation, but their exact roles are unknown. Dr. Barack aims to investigate how monkeys learn these state representations, using a complex, sequential decision-making task. During this novel behavioral task, similar to the boardgame “Battleship,” the team with elucidate learning in a complex environment, measuring associated neural mechanisms of circuits in the amygdala and orbitofrontal cortex activated in learning and decision-making. These results could promote the creation of computational models that may provide insights about animal and human interactions with the world.

Despite physical therapy, about 50% of stroke survivors must live with impaired hand function, impacting daily activities for the remainder of their life. However, recent studies in rats have suggested that low-frequency cortical stimulation may help alleviate such symptoms. In order to translate this work to humans, Dr. Khanna aims to use a multiscale model of electrophysiological recording to monitor motor and somatosensory activity during dexterous control, comparing affected and unaffected hemispheres in non-human primates (NHP) recovering from a stroke. The results may inform development of therapeutic techniques for stroke-related motor dysfunction, while improving our understanding of neuromodulation.

Many orofacial behaviors critical for survival, such as chewing, drinking, and breathing, require motor command modulation based on information from proprioceptors. However, since many previous studies of proprioceptors were not performed in awake, behaving animals, our understanding of this system is lacking. Dr. Olson aims to target and record from mouse jaw-innervating proprioceptors in the mensencephalic trigeminal (MeV) nucleus, while the animals perform orofacial behaviors. Using advancements in in vivo physiology, behavioral analysis, and computational techniques, the study will entail recording from these neurons and mapping the functional organization of the area. The findings may improve our understanding of how the brain controls jaw movements in real-time.

fMRI can be a powerful tool to measure activity throughout the entire brain. But, because it is an indirect measure of activity through changes in blood oxygenation, it is subject to error based on local microstructural and microvascular properties of the cortex. Thus, Dr. Blazejewska intends to remove these biases in fMRI results, providing a framework for a more accurate representation of neural activity. Using histology of human brain specimens with advanced ex vivo and in vivo imaging, the team will map between tissue microarchitecture and fMRI results, correcting errors due to microstructure. These results should allow for a more accurate measurement of functional activity across all cortical layers, promoting a better understanding of the brain’s circuitry.

GABAergic interneurons have a key role in regulating circuits in the brain, and their dysfunction is linked to neurodevelopmental diseases. It is known that diversity exists between classes of interneurons, but the extent and mechanisms of this diversity are unknown. Dr. Crow will explore the transcriptional, epigenetic, and developmental mechanisms that govern interneuron diversity, in a cross-species analysis. The work will leverage computational and phylogenetic models, machine learning, and advances in single cell RNA-sequencing technology to shed light on interneuron identity.

Dopamine (DA) inputs in the midbrain influence striatal activity in the basal ganglia, and dysfunction in this system is associated with many neurological and psychiatric illnesses. Dr. Vu aims to measure dopamine release onto the dendrites of single striatal neurons in real-time using 2-photon microscopy, and map functionally-relevant dopamine release onto striatal dendrites during different behaviors in mice. This work will inform our understanding of the spatial organization of dopamine inputs onto single neurons in the striatum, as well as how these inputs affect post-synaptic cell firing.

Many organisms are capable of interval timing, as it is essential to many tasks important for survival. However, no research has determined a neural mechanism for this process.  Dr. Smart will study the neural mechanisms of interval timing in a coordinated network throughout the brain, and how these estimates of time affect behavior. The work will leverage behavioral assays, whole-brain neural activity imaging, and genetic techniques in the Drosophila brain. These findings will improve our understanding of how the brain keeps time.

Recent advances in sequencing technology are revealing diverse cell types across the human and mouse brains, with some transient progenitor cell types found to exist only during development. In addition to this diversity of cell types, early evidence points to diversity in lipid expression and function throughout the brain. Dr. Bhaduri aims to characterize the developing human cortex across multiple regions, linking differences in transcriptomic and lipidomic data in order to understand how metabolism and transcriptional regulation interact to determine cell fate decisions in cortical progenitors. The work will offer insight into how the human brain develops.

Habituation is a form of learning by which organisms become less responsive to repetitive stimuli. While often impaired in disorders with complex cognitive symptoms, and thus has relevance to human disease, there are significant gaps in the understanding of habituation learning. To address this challenge, Dr. Nelson will study the critical role of protein modifications in habituation learning, using larval zebrafish as a model system. The project will involve training in protein modification and in vivo electrophysiology, integrating these approaches into a well-rounded system to examine learning across genes, circuits, and behavior. Success of the project may reveal how post-translational protein modifications influence synaptic plasticity within defined neural circuits as we learn.

Traumatic events can result in anxiety disorders, including post-traumatic stress disorder (PTSD), a hallmark of which is amplified expression of fear and resistance to behavioral therapies. While the ventromedial prefrontal cortex (vmPFC) is thought to have a fear-inhibiting role, activity in its subregions is also elevated in many PTSD patients. To understand this functional dichotomy, Dr. Cummings will investigate the mechanisms by which vmPFC subregions encode learned fear by using a range of approaches, including calcium imaging, circuit tracing, in vivo optogenetic manipulation, and ex vivo electrophysiology in mice. Success of the project should result in characterization of the role of vmPFC in the regulation of fear memory, which may inform existing models of fear circuitry and help elucidate the mechanisms that are recruited in fear learning.