Janez Rozman
Medical Faculty, University of Ljubljana, Slovenia
Title: A model and setup for selective infrared stimulation of isolated porcine vagus nerve
Biography
Biography: Janez Rozman
Abstract
Statement of the Problem: Electrical nerve stimulation has been widely applied in both neuroscience and clinical practice. Among numerous alternative neuro-modulation techniques, opto-thermal methods are becoming more and more popular. The foremost advantage of using infrared light (IR) pulses for nerve stimulation over electrical methods is high spatial resolution, lack of stimulation artifacts and lack of electrochemical processes.
Methodology & Theoretical Orientation: As concluded by Wells et all. (2007), neuronal activation using IR occurs mainly by a photo-thermal mechanism due to IR-induced brief temperature transients (dT/dt and dT/dx). The rapid temperature rise induces a transient change in the electrical capacitance of the neuron's plasma membrane, which in turn depolarizes the cell and induces a propagating action potential (AP). The wavelength was chosen based on the desired penetration depth in the nerve tissue. We propose to use short-wavelength infrared (SWIR, IR-B DIN) light with wavelength of 1936 microns emitted by a Light Emitting Diode and conducted using an optical fiber.
Findings: We developed the equipment including a measuring chamber, a SWIR source, optical chopper, multi-electrode recording spiral nerve cuff and CAP amplifier. The stimulator is capable of delivering extremely steep rectangular SWIR pulses ranging from 100 to 500 µs and energy of up to ∼1 J∕cm2. The induced thermal transients should have a highly localized nature and fast temporal dynamics within the particular superficial region of on an isolated porcine vagus nerve.
Conclusion & Significance: This report describes the challenges related to the development of IR neuro-modulation therapies. Results will be relevant for further development of the VNS methods and implantable systems to be potentially used in clinical practice.