Brown’s Laboratory for Neurophysiology and Neuromodulation
The Laboratory for Neurophysiology and Neuromodulation studies neural circuits in humans and nonhuman animal models to understand action planning, learning, and high-level cognition, to place neurological and psychiatric dysfunction into these mechanistic contexts, and to design improved methods of neurophysiological biomarker detection and more effective forms of brain modulation. One of the ultimate goals of the lab is to transform the techniques of neuromodulation such that treatment can be customized to the individual patient’s condition, maximizing relief and minimizing side effects. The lab is directed by Wael F. Assad, MD, PhD, Associate Professor of Neurosurgery and Neuroscience.
Deep-brain stimulation (DBS), the best-known method of neuromodulation, is currently delivered in a constant, or unmodulated, “open-loop” manner, often resulting in periods of inadequate stimulation as a patient’s symptoms fluctuate. In “closed-loop,” or modulated DBS, treatment is modulated in real time, according to the patient’s symptoms. A truly individualized approach will require the ability to quantify and classify the patient’s symptoms during treatment. The objective determination of optimal settings will also enable more complex stimulation devices, such as ones based on electrical field shaping.
The four hardware and analytic tools described below are key components of the lab’s approach to achieving individualized neuromodulation therapy.
Tech ID 2253: Intracranial fixation device The intracranial fixation device is intended for use during the implantation of neural probes, such as DBS electrodes, recording electrodes, optical probes, dialysis probes, injection cannulae, and aspiration cannulae/fluid shunts.
Intracranial probes are currently inserted through a burr hole during surgery with the use of a guide system involving MRI, CT, or a stereotactic device. Such methods are overly complex and/or prone to failure; small divergences in probe placement can have a significant effect on clinical outcome. Our device relies on simple suturing techniques that surgeons routinely use to secure the intracranial probe to a fixation device, which prevents the probe from moving. The result is rapid and reliable fixation of the probe relative to anatomical position. US 9,675,783 B2; patent issued, 2017-06-13. Tech ID 2548: Peel-away electrode placement catheter for deep brain stimulation (DBS) Currently, flexible and delicate stimulating electrodes are guided to their deep-brain targets through thin steel guide tubes that must be withdrawn over the extracranially protruding (proximal) end of the implanted DBS electrode after insertion. The connection between the proximal end of the electrode and other components of the stimulator system must be established after guide tube withdrawal, limiting the complexity of the electrical connections possible.
Our peel-away electrode placement catheter re-imagines the uniform steel insertion catheter design typically used in DBS surgery during the electrode insertion step. The catheter casing can be “peeled away” by the surgeon as it is withdrawn over the electrode so it does not interrupt pre-established connections between the stimulating or recording electrode implanted through the catheter and the rest of the DBS system. Novel design components include (1) an outer casing made of silicone that can split in half longitudinally along perforations to enable controlled deformation upon withdrawal from the brain tissue; (2) an outer silicone casing that includes dual steel hemicylinders embedded such that the tube retains its rigidity upon insertion into the brain tissue, until intentional tearing stresses are applied to break it along the perforations; and (3) a casing that is readily deformable with less than 5 N of bilateral force applied to opposite sides of the tube. US 17/151,970; patent pending, priority date 2018-02-15.
Tech ID 2565: Continuous motor task for objectively quantifying motor symptoms in movement disorders Motor symptoms present differently across patients and change over time, on both shorter and longer timescales. Current methods of assessing motor symptoms are based on qualitative observations made by the clinician every few months. This is inadequate for monitoring movement to analyze symptoms on short timescales and optimize therapy.
Our continuous motor task collects movement data to quantify motor symptoms suitable for both short and long timescales, to characterize patient–specific symptom profiles, to study correlating neurophysiological data, and to optimize medical and surgical therapies. The motor task captures goal–directed movement over a specified amount of time as the patient tracks or approaches a changing on-screen target. The task can be administered on a wide range of platforms, including portable tablets, computers, joysticks, buttons, and robotic arms. This versatility allows use in multiple settings. The collected data can be used in real-time for applications such as automated DBS programming and complete closed–loop neuromodulation. It can also be used to generate patient–specific neural biomarkers, quantify disease progression, and adjust medication. US17/312,155; patent pending, priority date 2018-12-11.
Tech ID 3071: Novel implantable device to augment existing DBS devices to allow expanded, chronic recording and stimulation capabilities Currently, clinicians rely on patients’ subjective recollection of their condition and adjust DBS therapy by trial and error, based upon the imperfect data. Neural biomarkers of disease, monitored chronically, could potentially augment clinical judgement by providing objective data regarding disease burden and response to therapy. Such biomarkers could be used to derive control signals for neuromodulation in real-time.
Current implantable neuromodulation devices are limited in their recording and stimulation capabilities, and have minimal on-board processing to implement sophisticated models for transforming neural activity biomarkers to appropriate stimulation patterns. Our novel implantable device augments traditional DBS devices to expand their capability to detect and understand neural activity biomarkers and to implement more complex, patient–specific algorithms for neuromodulation therapy. The brain implantable device is configured to supersede or override a function of the simultaneously implanted DBS system under controlled circumstances to enable enhanced acquisition of neural signals and testing of novel algorithms for brain stimulation. 63/076,453; provisional filed. 2020-9-10
Principal Investigator Wael F. Asaad, MD, PhD Associate Professor of Neurosurgery and Neuroscience Brown University wael.asaad@brown.edu https://vivo.brown.edu/display/wasaad