Theory & Data Analysis Tools

PROJECT SUMMARY Tourette syndrome (TS) is a continuous lifelong condition that is highly prevalent, socially disabling, and in some severe cases, physically injurious. DBS has emerged as a promising treatment option for addressing uncontrollable tics in medically resistant and severe cases of TS frequently involving self-injurious behavior. We have undertaken a major informatics initiative by establishing the International TS DBS Registry and Database, a multi-country consortium that has captured long term outcomes of 277 TS DBS patients representing 50-75% of all TS DBS cases worldwide.

Project Summary: High frequency oscillations (HFOs) of intracranial EEG (iEEG) have the potential to identify the surgical resection area/seizure onset zone (SOZ) in patients with drug resistant epilepsy. However, multiple reports indicate that HFOs can be generated not only by epileptic cerebral tissue but also by non-epileptic sites often including eloquent regions such as motor, visual and language cortices.

Limited recovery of function after stroke remains a major problem for millions. Disability persists in many, especially when hand function is limited. Existing therapies are limited and many have difficulties with activities of daily living, even after rehabilitation. Electrical stimulation of the brain has been proposed and used in early studies to try and aid recovery. In animals, stimulation delivered to the brain at precise times may improve the effect of stimulation.

The neural circuitry of the spinal cord has a unique, repetitive structure that forms an especially promising target for control via electrical stimulation. Furthermore, this structure allows the essential circuits for generation of movements to be preserved below the level of a spinal cord injury (SCI).

Project Summary Ultrasound has been explored as a modality to modulate nerves and muscles back in the 1920s. A number of recent studies have demonstrated the feasibility of using ultrasound to stimulate peripheral nerves, spinal cord, and brain. Yet, it has been difficult to determine whether ultrasound stimulation is via direct modulation of the membrane voltage or via indirect synaptic or network pathways.

Summary Neuroscience has an essential requirement for large-scale perturbation tools. Such tools would be transformative in the mapping of brain function, the causal testing of neurotheoretic models, and the diagnosis and treatment of neurological disorders. The proposed five-year project is aimed at uncovering the fundamental mechanisms of US stimulation through the reciprocity of mathematical analysis, computational modeling and experimental validation.

Abstract Magnetogenetics is a recently proposed method for stimulating cells using electromagnetic fields. In one approach, radio-frequency (RF) electromagnetic fields are applied to stimulate membrane channel proteins such as TRPV1 and TRPV4 that are attached to ferritins. The concept is highly attractive as it enables wireless neural stimulation without limitation on penetration depth or the requirement of invasive surgeries.

Microstimulation has been an invaluable tool for neuroscience researchers to infer functional connections between brain structures or causal links between structure and behavior. In recent years, therapeutic microstimulation is gaining interest for the restoration of visual, auditory and somatosensory functions as well as emerging applications in bioelectronic medicine. Current neural stimulation parameters and safety limits need to be revised for microelectrodes using more systematic and advanced methodologies.

Our long-term goals are to better understand the response of neurons to artificial stimulation, and, to use this knowledge to develop new and more effective strategies for stimulating non- or improperly-functioning neurons of the CNS. The development of models that comprehensively and accurately predict the response of neural populations to electric stimulation has proven challenging, in part because of the significant morphological differences that can exist even between nearby cells, and, a lack of understanding as to how such differences shape each cell’s response to stimulation.