Laser stimulation of auditory neurons: effect of shorter pulse duration and penetration depth

Biophys J. 2008 Apr 15;94(8):3159-66. doi: 10.1529/biophysj.107.117150. Epub 2008 Jan 11.


We have pioneered what we believe is a novel method of stimulating cochlear neurons, using pulsed infrared radiation, based on the hypothesis that optical radiation can provide more spatially selective stimulation of the cochlea than electric current. Very little of the available optical parameter space has been used for optical stimulation of neurons. Here, we use a pulsed diode laser (1.94 microm) to stimulate auditory neurons of the gerbil. Radiant exposures measured at CAP threshold are similar for pulse durations of 5, 10, 30, and 100 micros, but greater for 300-micros-long pulses. There is evidence that water absorption of optical radiation is a significant factor in optical stimulation. Heat-transfer-based analysis of the data indicates that potential structures involved in optical stimulation of cochlear neurons have a dimension on the order of approximately 10 microm. The implications of these data could direct further research and design of an optical cochlear implant.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Action Potentials / physiology*
  • Action Potentials / radiation effects
  • Animals
  • Dose-Response Relationship, Radiation
  • Evoked Potentials, Auditory / physiology*
  • Evoked Potentials, Auditory / radiation effects
  • Gerbillinae
  • Lasers*
  • Neurons, Afferent / physiology*
  • Neurons, Afferent / radiation effects
  • Photic Stimulation / methods*
  • Radiation Dosage
  • Spiral Ganglion / physiology*