Laser stimulation of auditory neurons at high repetition rate

Izzo, Agnella D.; Littlefield, Philip D.; Walsh, Joseph T.; Webb, Jim; Ralph, Heather; Bendett, Mark; Jansen, E.; Richter, Claus Peter

doi:10.1117/12.700846

Cited by 10 publications

(9 citation statements)

References 33 publications

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“…Optical stimulation of the auditory nerve has been studied in normal hearing gerbils (Izzo et al, 2006a, b; Izzo et al, 2007a–d; Izzo et al, 2008; Matic et al, 2011), deafened gerbils (Richter et al, 2008), the mouse (Suh et al, 2007), the guinea pig (Moreno et al, 2011; Richter et al, 2011b), and the cat (Rajguru et al, 2011). In a first series of experiments, a Ho:YAG laser was used to stimulate the auditory nerve of gerbils (Izzo et al, 2006b).…”

Section: Discussionmentioning

confidence: 99%

Acute Damage Threshold for Infrared Neural Stimulation of the Cochlea: Functional and Histological Evaluation

Goyal¹,

Rajguru²,

Matic³

et al. 2012

The Anatomical Record

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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 (k ¼ 1,869 nm), the pulse duration (100 ls), the pulse repetition rate (250 Hz), and the radiant energy (0-127 lJ/pulse). For up to 5 hr of continuous irradiation at 250 Hz and at radiant energies up to 25 lJ/pulse, we did not observe any functional or histological damage in the cochlea. Functional loss was observed for energies above 25 lJ/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 lJ/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.

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Section: Discussionmentioning

confidence: 99%

Acute Damage Threshold for Infrared Neural Stimulation of the Cochlea: Functional and Histological Evaluation

Goyal¹,

Rajguru²,

Matic³

et al. 2012

The Anatomical Record

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“…Acute studies of high repetition rate stimulation demonstrate no change in CAP amplitude while stimulating up to 200 Hz for up to 8 h. 3,42,43 Other parameters, such as placement of optical sources, will be examined and optimized for an optical cochlear implants. In summary, the results provided in this paper support the view that optical radiation can provide spatial selectivity of stimulation similar to acoustic stimulation of the cochlea.…”

Section: Discussionmentioning

confidence: 99%

Spatial extent of cochlear infrared neural stimulation determined by tone-on-light masking

Matic¹,

Walsh²,

Richter³

2011

J. Biomed. Opt.

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Abstract. Artificial neural stimulation is widely used in clinic, rehabilitation, and research. One of the limitations of electrical stimulation is the current spread in tissue. Recently, pulsed mid-infrared laser stimulation of nerves has been investigated as an alternative stimulation method. The likely benefits of infrared neural stimulation (INS) include spatial selectivity of stimulation, noncontact mode of operation, and the lack of stimulation artifact in simultaneous electrical recordings. The hypothesis for this study is that INS of the cochlear spiral ganglion at low pulse energy is as spatially selective as low-level tonal stimulation of the cochlea. Spatial selectivity was measured using a masking method. An optical pulse with fixed optical parameters was delivered through a 200-μm diameter optical fiber. An acoustic tone, variable in frequency and level, was presented simultaneously with the optical pulse. Tone-on-light masking in gerbils revealed tuning curves with best frequencies between 5.3 and 11.4 kHz. The width of the tone-on-light tuning curves was similar to the width of tone-on-tone tuning curves. The results indicate that the spatial area of INS in the gerbil cochlea is similar to the cochlear area excited by a low level acoustic tone, showing promising results for future use of INS in implantable cochlear prostheses. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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“…Indeed, a laser can be used to stimulate the auditory system for up to six hours at 13 Hz repetition rate without significantly changing the CAP amplitude (Izzo et al, 2007b). Moreover, auditory neurons could be stimulated for 2 hours at a 400 Hz repetition rate and the CAP peak-to peak amplitude did not change significantly (Izzo et al, 2007d). Chronic studies are underway but are not completed yet.…”

Section: Introductionmentioning

confidence: 99%

Optical stimulation of auditory neurons: Effects of acute and chronic deafening

et al. 2008

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In developing neural prostheses, particular success has been realized with cochlear implants. These devices bypass damaged hair cells in the auditory system and electrically stimulate the auditory nerve directly. In contemporary cochlear implants, however, the injected electric current spreads widely along the scala tympani and across turns. Consequently, stimulation of spatially discrete spiral ganglion cell populations is difficult. In contrast to electrical stimulation, it has been shown that extremely spatially selective stimulation is possible using infrared radiation (e.g. Izzo et al., 2007a). Here, we explore the correlation between surviving spiral ganglion cells, following acute and chronic deafness induced by neomycin application into the middle ear, and neural stimulation using optical radiation and electrical current.In vivo experiments were conducted in gerbils. Before the animals were deafened, acoustic thresholds were obtained and neurons were stimulated with optical radiation at various pulse durations, radiation exposures, and pulse repetition rates. In one group of animals, measurements were made immediately after deafening, while the other group was tested at least four weeks after deafening. Deafness was confirmed by measuring acoustically evoked compound action potentials. Optically and electrically evoked compound action potentials and auditory brainstem responses were determined for different radiation exposures and for different electrical current amplitudes, respectively. After completion of the experiments, the animals were euthanized and the cochleae were harvested for histology.Acoustically evoked compound action potential thresholds were elevated by more than 40 dB after neomycin application in acutely deaf and more than 60 dB in chronically deaf animals. Compound action potential thresholds, which were determined with optical radiation pulses, were not significantly elevated in acutely deaf animals. However, in chronically deaf animals optically evoked CAP thresholds were elevated. Changes correlated with the number of surviving spiral ganglion cells and the optical parameters that were used for stimulation.

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Laser stimulation of auditory neurons at high repetition rate

Cited by 10 publications

References 33 publications

Acute Damage Threshold for Infrared Neural Stimulation of the Cochlea: Functional and Histological Evaluation

Acute Damage Threshold for Infrared Neural Stimulation of the Cochlea: Functional and Histological Evaluation

Spatial extent of cochlear infrared neural stimulation determined by tone-on-light masking

Optical stimulation of auditory neurons: Effects of acute and chronic deafening

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