Neural engineering research, including both fundamental and translational activities. Primary areas of interest are anodic stimulation, low-amplitude neuromodulation (e.g., sub-perception stimulation of peripheral nerve or spinal cord), and photobiomodulation effects on neural elements.
Understanding mechanism(s) of low-amplitude stimulation
Although in wide use, the SCS field cannot explain how “stimulation” at amplitudes ~6% of the perception threshold result in an analgesic effect, and hypotheses vary widely. It is possible that the application of the electric field does not directly stimulate neural elements, and clinical phenomena consistent with this possibility include the observation of wash-in times ranging from immediate (our new discovery at Boston Scientific) or very long (hours to days), and relationships between stimulation parameters that we’ve discovered empirically in clinical studies, but that do not have an identified relationship with first principles of neurostimulation (e.g., strength duration curve). In my laboratory, we will use pre-clinical models (including models of neuropathic pain) to further characterize sub-perception stimulation effects on pain, determine whether or not clinically relevant “stimulation” parameters applied to peripheral nerve or dorsal columns directly excite or inhibit neural elements (one possible mechanistic basis), and evaluate alternative hypotheses (e.g., glial-based effects, non-synaptic effects, etc.). We anticipate that as mechanistic understanding unfolds in the laboratory, the principles will be applicable to other neuromodulation applications, such as deep brain stimulation (DBS) and afford new opportunities.
Mechanisms and applications of photobiomodulation
The use of light at specific wavelengths to elicit a physiological response or photobiomodulation (PBM) has a history dating back to the late 1960’s and includes a large body of literature, but the field has not yet produced a high impact therapy. I believe that the reasons for this are surmountable (e.g., much work done with transcutaneous preps and implantable PBM would overcome some of the inherent limitations), and that the literature describes effects of PBM on neural systems that compel further consideration. One observation is the ability of light with wavelength of approx. 800 nm to halt C-fiber conduction of action potentials. Although still early, the phenomenon has been published by multiple labs,,,. In collaboration with optics experts at CWRU, we are characterizing this phenomenon, further investigating mechanisms, and evaluating application as a pain therapy. We will expand these efforts to understand other neural-related PBM phenomena of interest, such as anti-inflammatory effects, and neuroprotective properties.
Computational modeling of neuronal excitation/inhibition is an important part of our lab activities. In addition to modeling of electric fields and non-linear models of neurons, our lab models light transport, and we will use both types of models to understand electrical stimulation and PBM-based mechanisms, to predict required therapeutic dosing, and to do model-based design of candidate therapy systems.
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