Chronic intracochlear electrical stimulation in the neonatally deafened cat. I: Expansion of central representation

Snyder, Russell L.; Rebscher, Stephen J.; Cao, Keli; Leake, Patricia A.; Kelly, Kevin E.

doi:10.1016/0378-5955(90)90030-s

Cited by 173 publications

(152 citation statements)

References 43 publications

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“…inserted through the round window into the scala tympani. Wires from all electrodes were led under the skin and muscle to a percutaneous connector mounted Electrode configurations on the skull (Pfingst et al 1989). A remote ground electrode was implanted under the temporalis muscle A variety of electrode configurations were tested.…”

Section: Methodsmentioning

confidence: 99%

“…For many years, it was assumed that narrow electode number of neurons activated increases dramatically as stimulus level is increased above the threshold of the configurations, such as narrowly spaced bipolar configurations, would be advantageous for speech recognimost sensitive neurons (Snyder et al 1990;Kral et al 1998). Also, as noted above, increases in stimulus level tion because they would allow for better separation of the neural populations carrying information preresult in improvement in some types of discrimination.…”

Section: Introductionmentioning

confidence: 99%

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Effects of Electrode Configuration and Stimulus Level on Rate and Level Discrimination with Cochlear Implants

Morris

Pfingst

2000

JARO

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ABSTRACTmuch of the psychophysical dynamic range. Results showed large effects of current level on discrimination in many cases. However, effects of electrode configuraRecent studies have demonstrated that speech perception at comparable levels within the dynamic range tion with cochlear implants can be significantly were smaller or absent. Furthermore, the effect of affected by electrode configuration. Contrary to level on discrimination was independent of electrode expectations, broader configurations (monopolar or configuration in most cases even though the rate of broad bipolar) produced equal or better speech recogspread of neural activation with level is expected to nition compared with narrower configurations (nardepend on electrode configuration. Possible interprerow bipolar or common ground). One hypothesis that tations of these results are that (1) the current level would account for these results is that broader configuadjustments necessary to achieve comparable loudness rations excite larger populations of neurons providing for the various configurations significantly countered a more robust representation of information on each any effects of electrode configuration on the size of channel of the prosthesis. It is known that the number the activated neural population, or (2) the effects of of neurons excited by an electrical stimulus increases level on discrimination do not result from its effects considerably as the stimulus level increases. Furtheron the spatial extent of neural activation. more, many types of discrimination improve as a func-

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effects of Electrode Configuration and Stimulus Level on Rate and Level Discrimination with Cochlear Implants

Morris

Pfingst

2000

JARO

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“…In comparison, acoustic stimulation has been shown to produce relatively narrow, selective distributions of neuronal activity. This has been demonstrated in animal studies in which neuronal responses to acoustic and monopolar electrical stimulation were recorded in the auditory nerve (Kral et al 1998) and inferior colliculus (IC;Snyder et al 1990Snyder et al , 2004Snyder et al , 2008Middlebrooks and Snyder 2007). Comparisons of neuronal responses to monopolar electrical stimulation and bipolar electrical stimulation (one intracochlear stimulating contact and a second intracochlear return contact) have shown mixed results.…”

Section: Introductionmentioning

confidence: 99%

“…Comparisons of neuronal responses to monopolar electrical stimulation and bipolar electrical stimulation (one intracochlear stimulating contact and a second intracochlear return contact) have shown mixed results. The majority of studies have shown more broadly distributed neuronal activation for monopolar than for bipolar intracochlear stimulation, including studies in the auditory nerve (van den Honert and Stypulkowski 1987;Kral et al 1998), inferior colliculus (Merzenich and White 1977;Snyder et al 1990Snyder et al , 2004Snyder et al , 2008Middlebrooks and Snyder 2007), and auditory cortex (Bierer and Middlebrooks 2002); but a few studies have shown similar neuronal activation patterns for monopolar and bipolar stimulation at low to moderate stimulus intensities (Liang et al 1999;Rebscher et al 2001;Smith and Delgutte 2007).…”

Section: Introductionmentioning

confidence: 99%

Monopolar Intracochlear Pulse Trains Selectively Activate the Inferior Colliculus

Schoenecker

Bonham

Stakhovskaya

et al. 2012

JARO

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Previous cochlear implant studies using isolated electrical stimulus pulses in animal models have reported that intracochlear monopolar stimulus configurations elicit broad extents of neuronal activation within the central auditory system-much broader than the activation patterns produced by bipolar electrode pairs or acoustic tones. However, psychophysical and speech reception studies that use sustained pulse trains do not show clear performance differences for monopolar versus bipolar configurations. To test whether monopolar intracochlear stimulation can produce selective activation of the inferior colliculus, we measured activation widths along the tonotopic axis of the inferior colliculus for acoustic tones and 1,000-pulse/s electrical pulse trains in guinea pigs and cats. Electrical pulse trains were presented using an array of 6-12 stimulating electrodes distributed longitudinally on a space-filling silicone carrier positioned in the scala tympani of the cochlea. We found that for monopolar, bipolar, and acoustic stimuli, activation widths were significantly narrower for sustained responses than for the transient response to the stimulus onset. Furthermore, monopolar and bipolar stimuli elicited similar activation widths when compared at stimulus levels that produced similar peak spike rates. Surprisingly, we found that in guinea pigs, monopolar and bipolar stimuli produced narrower sustained activation than 60 dB sound pressure level acoustic tones when compared at stimulus levels that produced similar peak spike rates. Therefore, we conclude that intracochlear electrical stimulation using monopolar pulse trains can produce activation patterns that are at least as selective as bipolar or acoustic stimulation.

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“…Respiratory rate, heart rate, and body temperature were monitored throughout all procedures, and body temperature was maintained using a warm water recirculating blanket. The electrophysiological recording methods have been described in detail in several previous publications (Snyder et al 1990Leake et al 2000;Leake and Rebscher 2004;Vollmer et al 1999Vollmer et al , 2005. Briefly, tungsten microelectrodes were used to record responses of multi-neuronal clusters and single neurons in several penetrations through the IC that were made along a standardized trajectory orthogonal to the tonotopic gradient of the IC.…”

Section: Electrophysiological Recordingmentioning

confidence: 99%

Topography of Auditory Nerve Projections to the Cochlear Nucleus in Cats after Neonatal Deafness and Electrical Stimulation by a Cochlear Implant

Leake

Hradek

Bonham

et al. 2008

JARO

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We previously reported that auditory nerve projections from the cochlear spiral ganglion (SG) to the cochlear nucleus (CN) exhibit clear cochleotopic organization in adult cats deafened as neonates before hearing onset. However, the topographic specificity of these CN projections in deafened animals is proportionately broader than normal (less precise relative to the CN frequency gradient). This study examined SG-to-CN projections in adult cats that were deafened as neonates and received a unilateral cochlear implant at ∼7 weeks of age. Following several months of electrical stimulation, SG projections from the stimulated cochleae were compared to projections from contralateral, non-implanted ears. The fundamental organization of SG projections into frequency band laminae was clearly evident, and discrete projections were always observed following double SG injections in deafened cochleae, despite severe auditory deprivation and/or broad electrical activation of the SG. However, when normalized for the smaller CN size after deafness, AVCN, PVCN, and DCN projections on the stimulated side were broader by 32%, 34%, and 53%, respectively, than projections in normal animals (although absolute projection widths were comparable to normal). Further, there was no significant difference between projections from stimulated and contralateral non-implanted cochleae. These findings suggest that early normal auditory experience may be essential for normal development and/or maintenance of the topographic precision of SG-to-CN projections. After early deafness, the CN is smaller than normal, the topographic distribution of these neural projections that underlie frequency resolution in the central auditory system is proportionately broader, and projections from adjacent SG sectors are more overlapping. Several months of stimulation by a cochlear implant (beginning at ∼7 weeks of age) did not lessen or exacerbate these degenerative changes observed in adulthood. One clinical implication of these findings is that congenitally deaf cochlear implant recipients may have central auditory system alterations that limit their ability to achieve spectral selectivity equivalent to postlingually deafened subjects.

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Chronic intracochlear electrical stimulation in the neonatally deafened cat. I: Expansion of central representation

Cited by 173 publications

References 43 publications

Effects of Electrode Configuration and Stimulus Level on Rate and Level Discrimination with Cochlear Implants

Effects of Electrode Configuration and Stimulus Level on Rate and Level Discrimination with Cochlear Implants

Monopolar Intracochlear Pulse Trains Selectively Activate the Inferior Colliculus

Topography of Auditory Nerve Projections to the Cochlear Nucleus in Cats after Neonatal Deafness and Electrical Stimulation by a Cochlear Implant

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