Acute Damage Threshold for Infrared Neural Stimulation of the Cochlea: Functional and Histological Evaluation
Article first published online: 8 OCT 2012
Copyright © 2012 Wiley Periodicals, Inc.
The Anatomical Record
Special Issue: The Anatomy and Biology of Hearing and Balance: Cochlear and Vestibular Implants
Volume 295, Issue 11, pages 1987–1999, November 2012
How to Cite
Goyal, V., Rajguru, S., Matic, A. I., Stock, S. R. and Richter, C.-P. (2012), Acute Damage Threshold for Infrared Neural Stimulation of the Cochlea: Functional and Histological Evaluation. Anat Rec, 295: 1987–1999. doi: 10.1002/ar.22583
- Issue published online: 22 OCT 2012
- Article first published online: 8 OCT 2012
- Manuscript Received: 24 JUL 2012
- Manuscript Accepted: 24 JUL 2012
- The National Institute on Deafness and Other Communication Disorders
- National Institutes of Health
- Department of Health and Human Services. Grant Number: HHSN260-2006-00006-C/NIH No. N01-DC-6-0006
This article provides a mini review of the current state of infrared neural stimulation (INS), and new experimental results concerning INS damage thresholds. INS promises to be an attractive alternative for neural interfaces. With this method, one can attain spatially selective neural stimulation that is not possible with electrical stimulation. INS is based on the delivery of short laser pulses that result in a transient temperature increase in the tissue and depolarize the neurons. At a high stimulation rate and/or high pulse energy, the method bears the risk of thermal damage to the tissue from the instantaneous temperature increase or from potential accumulation of thermal energy. With the present study, we determined the injury thresholds in guinea pig cochleae for acute INS using functional measurements (compound action potentials) and histological evaluation. The selected laser parameters for INS were the wavelength (λ = 1,869 nm), the pulse duration (100 μs), the pulse repetition rate (250 Hz), and the radiant energy (0–127 μJ/pulse). For up to 5 hr of continuous irradiation at 250 Hz and at radiant energies up to 25 μJ/pulse, we did not observe any functional or histological damage in the cochlea. Functional loss was observed for energies above 25 μJ/pulse and the probability of injury to the target tissue resulting in functional loss increased with increasing radiant energy. Corresponding cochlear histology from control animals and animals exposed to 98 or 127 μJ/pulse at 250 Hz pulse repetition rate did not show a loss of spiral ganglion cells, hair cells, or other soft tissue structures of the organ of Corti. Light microscopy did not reveal any structural changes in the soft tissue either. Additionally, microcomputed tomography was used to visualize the placement of the optical fiber within the cochlea. Anat Rec, 2012. © 2012 Wiley Periodicasl, Inc.