Laser stimulation of the auditory nerve.
OBJECTIVE
For centuries, electric current has been used to stimulate neurons. Shortcomings of electrical stimulation include the contact between the stimulating electrode and the tissue, and the non-selective stimulation of the tissue. In contrast to electric stimulation, optical radiation can provide spatially selective neural stimulation without tissue contact.


METHODS
Acute in vivo experiments using gerbils were conducted to record optically evoked compound action potentials (CAPs) from the cochlea.


RESULTS
Optical radiation evokes CAPs in normal hearing animals and in deafened animals, in which cochleae lack outer and inner hair cells. Stimulation threshold was measured as 0.018+/-0.003 J/cm(2) (mean+/-SE). Laser radiation could be increased by 30-40 dB until drastic changes were seen in cochlear function. Cochlear response amplitudes to optical radiation were stable over extended stimulation times.


CONCLUSIONS
We have demonstrated that the auditory nerve can be stimulated by optical radiation. One potential clinical use of this technology would be for cochlear implants.
Izzo
Agnella D
AD
Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208, USA.
Richter
Claus-Peter
CP
Jansen
E Duco
ED
Walsh
Joseph T
JT
D000818:Animals; D003051:Cochlea / Q000502:physiology; D003056:Cochlear Nerve / Q000033:anatomy & histology / Q000502:physiology*; D005072:Evoked Potentials, Auditory / Q000502:physiology; D005849:Gerbillinae; D007834:Lasers; D013194:Staining and Labeling