Daniel W. Moran - US grants

[unreadable] DESCRIPTION (provided by applicant): Our primary research interest is in the area of motor neuroprosthetics. We seek to restore function to those suffering from neuromuscular disease and/or paralysis. This study will design and test a novel implantable, epidural micro-electrocorticographic (uECoG) array capable of recording high gamma band activity from the brain for long periods of time (years). We have developed a novel behavioral paradigm in a non-human primate virtual reality simulator to test and optimize the uECoG design. This neuroprosthetic research project will develop the knowledge, tools, and equipment needed to enable paralyzed individuals to control a computer cursor, wheelchair or robotic limb. The specific aims of this project are to 1) Develop and bench-test 5ECoG electrode array and implantable device platform; 2) Determine the optimal electrode diameters and inter-electrode spacings for both open-loop and closed-loop chronic recordings of gamma band activity over motor cortical regions in the non-human primate brain using an epidural 5ECoG electrode; and 3) Determine the optimal epidural 5ECoG signal parameters (i.e. center frequency and bandwidth) and motor cortical region (M1, Pmv, Pmd) for closed-loop BCI control of a computer cursor. PUBLIC HEALTH RELEVANCE: This project will design and test a novel, implantable, thin-film, epidural micro-electrocorticographic electrode array that will allow long-term chronic recording of brain activity. This new electrode design will be optimized for use in a brain-computer interface system that will allow paralyzed individuals to accurately control a computer mouse via direct brain control. [unreadable] [unreadable]

Human interaction with machines has always relied on some form of muscle movement to translate the brain's desired action to the machine (e.g. turning a knob). The objective of our project is to eliminate the need for muscle transformations in the man-machine interface. Using a new brain-computer interface (BCI) technology (electrocorticography or ECoG) pioneered by the research team, we will develop novel decoding algorithms to control the force/torque inputs to an external device directly. Likewise, by designing machine learning algorithms to identify and incorporate neural plasticity in the decoding schemes will allow the BCI to evolve over time. Finally, by combining brain signals from multiple areas to identify various brain states, we can identify and change the effectors to be controlled.

Intellectual Merit: All previous BCI studies decoded only kinematic signals to control computer cursors as well as robotic limbs. While kinematic control is a natural extension for disabled individuals trying to regain function lost by paralysis or amputation, a direct interface between the brain and the machine allows for much more elegant interaction. Thus, rather than controlling a robotic arm through the use of imagined self limb movements (a proxy of intention), one rather controls the device as if it was a part of their own body. For instance, mapping brain activity to kinetic parameters such as a robot?s torque motor allows the individual to directly control the forceful interactions within the system.

Broader Impact: One advantage of ECoG is that while it is an invasive recording technology, the electrodes can be placed epidurally which significantly reduces the risk profile for implantation. In the long term, this should allow ECoG-based BCIs to be accepted as a viable implant in able-bodied humans. Developing a safe and effective BCI modality for the general public will fundamentally change how humans interact with machines. No longer will humans require muscle activity as an intermediary to interact with machines. A whole new field of man-machine interfacing will be initiated where the brain builds complex internal models of the machine's dynamics (instead of musculoskeletal dynamics) for accurate and direct control of the machine's effectors.

In rehabilitating chronic motor-impaired stroke survivors with a brain computer interface (BCI), there is a fundamental gap in understanding how the brain changes with injury and in how a BCI can engage these dynamics to induce a functional recovery. The current barrier is the absence of a primate model that can test a BCI strategy in chronic stroke. The majority of animal models employ gray matter lesions, while the majority of clinically significant strokes involve the deeper white matter. The long-term goal of this project is to restore motor function by synergizing the patient's BCI rehabilitative strategy with their specific stroke-induced pathophysiology. The overall objective of this proposal is to create a nonhuman primate model for stroke that will examine the evolving physiology following a microvascular corticospinal tract (CST) lesion and test the impact of a neuroprosthetic intervention for functional restoration in the chronic setting. The central hypothesis is that BCI-driven motor rehabilitation for a CST injury will be effective when the control signals from the unaffected hemisphere are paired with proprioceptive feedback. The rationale for this research is that the animal model and the accrued scientific insights will create a mechanism-driven approach to neuroprosthetic solutions for stroke. Guided by strong preliminary evidence, we will test the central hypothesis with the following three specific aims: 1) Create a cortical electrode to enable multimodal measurements of the brain before and after a microvascular lesion to the CST, 2) Define acute and chronic alterations in cortical physiology and behavioral performance associated with a microvascular lesion to the CST, and 3) Restore motor function in macaque monkey with chronic CST injury using BCI rehabilitation. Under the first aim we will create a bihemispheric, MRI-invisible, micro-electrocorticographic (µECoG) implant that can measure the cortical physiology of ipsilesional and contralesional motor cortex and enable functional and anatomical magnetic resonance imaging. In the second aim, this implant, along with a new method for creating a stereotactic lesion to the posterior limb of the internal capsule, will enable us to link the micro-scale cortical electrophysiology with larger scale functional imaging as the brain changes from the central insult. Under the third aim, the chronically paretic monkeys will be rehabilitated using signal sources from the contralesional hemisphere. This project is innovative because it is a substantial departure from the status quo by expanding the role the unaffected hemisphere and bihemispheric interactions can play in BCI-mediated rehabilitation. The proposed research will be significant because the knowledge will create a critical bridge between motor function, electrophysiology, and functional imaging, which will vastly improve the characterization of how the cortical dynamics are perturbed with a white matter stroke and subsequently how these changes can be targeted for a tailored neuroprosthetic intervention. Ultimately, this will inform the development of novel treatments for stroke patients in the U.S.