title: Radiant energy during infrared neural stimulation at the target structure.
abstract: Infrared neural stimulation (INS) describes a method, by which an infrared laser is used to stimulate neurons. The major benefit of INS over stimulating neurons with electrical current is its spatial selectivity. To translate the technique into a clinical application it is important to know the energy required to stimulate the neural structure. With this study we provide measurements of the radiant exposure, at the target structure that is required to stimulate the auditory neurons. Flat polished fibers were inserted into scala tympani so that the spiral ganglion was in front of the optical fiber. Angle polished fibers were inserted along scala tympani, and rotating the beveled surface of the fiber allowed the radiation beam to be directed perpendicular to the spiral ganglion. The radiant exposure for stimulation at the modiolus for flat and angle polished fibers averaged 6.78±2.15 mJ/cm2. With the angle polished fibers, a 90° change in the orientation of the optical beam from an orientation that resulted in an INS-evoked maximum response, resulted in a 50% drop in the response amplitude. When the orientation of the beam was changed by 180°, such that it was directed opposite to the orientation with the maxima, minimum response amplitude was observed.
authors: Department of Otolaryngology, Northwestern University, 303 E. Chicago Ave, Searle 12-561, Chicago, IL 60611, USA ; Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Tech E310, Evanston, IL 60208, USA ; The Hugh Knowles Center, Department of Communication Sciences and Disorders, Northwestern University, Evanston, IL 60208, USA.
authors: Claus-Peter
authors: CP
authors: Richter
authors: Department of Biomedical Engineering, University of Miami, Miami FL 33146, USA ; Department of Otolaryngology, University of Miami, Miami FL 33136, USA.
authors: Suhrud
authors: S
authors: Rajguru
authors: Lockheed Martin Aculight, 22121 20th Ave SE, Bothell WA, USA.
authors: Ryan
authors: R
authors: Stafford
authors: Department of Molecular Pharmacology and Biological Chemistry, Northwestern University Feinberg School of Medicine, Chicago, IL 60611, USA.
authors: Stuart R
authors: SR
authors: Stock
keywords: cochlea; hearing; infrared neural stimulation; laser; optical stimulation