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Thomas WM, Zuniga SA, Sondh I, Leber M, Solzbacher F, Lenarz T, Lim HH, Warren DJ, Rieth L, Adams ME. Development of a feline model for preclinical research of a new translabyrinthine auditory nerve implant. Front Neurosci 2024; 18:1308663. [PMID: 38379760 PMCID: PMC10877721 DOI: 10.3389/fnins.2024.1308663] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Accepted: 01/02/2024] [Indexed: 02/22/2024] Open
Abstract
Cochlear implants are among the most successful neural prosthetic devices to date but exhibit poor frequency selectivity and the inability to consistently activate apical (low frequency) spiral ganglion neurons. These issues can limit hearing performance in many cochlear implant patients, especially for understanding speech in noisy environments and in perceiving or appreciating more complex inputs such as music and multiple talkers. For cochlear implants, electrical current must pass through the bony wall of the cochlea, leading to widespread activation of auditory nerve fibers. Cochlear implants also cannot be implanted in some individuals with an obstruction or severe malformations of the cochlea. Alternatively, intraneural stimulation delivered via an auditory nerve implant could provide direct contact with neural fibers and thus reduce unwanted current spread. More confined current during stimulation can increase selectivity of frequency fiber activation. Furthermore, devices such as the Utah Slanted Electrode Array can provide access to the full cross section of the auditory nerve, including low frequency fibers that are difficult to reach using a cochlear implant. However, further scientific and preclinical research of these Utah Slanted Electrode Array devices is limited by the lack of a chronic large animal model for the auditory nerve implant, especially one that leverages an appropriate surgical approach relevant for human translation. This paper presents a newly developed transbullar translabyrinthine surgical approach for implanting the auditory nerve implant into the cat auditory nerve. In our first of a series of studies, we demonstrate a surgical approach in non-recovery experiments that enables implantation of the auditory nerve implant into the auditory nerve, without damaging the device and enabling effective activation of the auditory nerve fibers, as measured by electrode impedances and electrically evoked auditory brainstem responses. These positive results motivate performing future chronic cat studies to assess the long-term stability and function of these auditory nerve implant devices, as well as development of novel stimulation strategies that can be translated to human patients.
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Affiliation(s)
- W. Mitchel Thomas
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
| | - Steven A. Zuniga
- Department of Otolaryngology-Head and Neck Surgery, University of Minnesota, Minneapolis, MN, United States
| | - Inderbir Sondh
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - Moritz Leber
- Blackrock Neurotech, Salt Lake City, UT, United States
| | - Florian Solzbacher
- Blackrock Neurotech, Salt Lake City, UT, United States
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, United States
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Medical University of Hannover, Hannover, Germany
| | - Hubert H. Lim
- Department of Otolaryngology-Head and Neck Surgery, University of Minnesota, Minneapolis, MN, United States
- Department of Biomedical Engineering, University of Minnesota, Minneapolis, MN, United States
| | - David J. Warren
- Department of Biomedical Engineering, University of Utah, Salt Lake City, UT, United States
- Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, UT, United States
| | - Loren Rieth
- Department Mechanical and Aerospace Engineering, West Virginia University, Morgantown, WV, United States
| | - Meredith E. Adams
- Department of Otolaryngology-Head and Neck Surgery, University of Minnesota, Minneapolis, MN, United States
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Normann RA, Fernandez E. Clinical applications of penetrating neural interfaces and Utah Electrode Array technologies. J Neural Eng 2016; 13:061003. [PMID: 27762237 DOI: 10.1088/1741-2560/13/6/061003] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
This paper briefly describes some of the recent progress in the development of penetrating microelectrode arrays and highlights the use of two of these devices, Utah electrode arrays and Utah slanted electrode arrays, in two therapeutic interventions: recording volitional skeletal motor commands from the central nervous system, and recording motor commands and evoking somatosensory percepts in the peripheral nervous system (PNS). The paper also briefly explores other potential sites for microelectrode array interventions that could be profitably pursued and that could have important consequences in enhancing the quality of life of patients that has been compromised by disorders of the central and PNSs.
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Affiliation(s)
- Richard A Normann
- Departments of Bioengineering and Ophthalmology, University of Utah, Salt Lake City, UT 84112, USA
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Davis TS, Parker RA, House PA, Bagley E, Wendelken S, Normann RA, Greger B. Spatial and temporal characteristics of V1 microstimulation during chronic implantation of a microelectrode array in a behaving macaque. J Neural Eng 2012; 9:065003. [PMID: 23186948 PMCID: PMC3521049 DOI: 10.1088/1741-2560/9/6/065003] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE It has been hypothesized that a vision prosthesis capable of evoking useful visual percepts can be based upon electrically stimulating the primary visual cortex (V1) of a blind human subject via penetrating microelectrode arrays. As a continuation of earlier work, we examined several spatial and temporal characteristics of V1 microstimulation. APPROACH An array of 100 penetrating microelectrodes was chronically implanted in V1 of a behaving macaque monkey. Microstimulation thresholds were measured using a two-alternative forced choice detection task. Relative locations of electrically-evoked percepts were measured using a memory saccade-to-target task. MAIN RESULTS The principal finding was that two years after implantation we were able to evoke behavioural responses to electric stimulation across the spatial extent of the array using groups of contiguous electrodes. Consistent responses to stimulation were evoked at an average threshold current per electrode of 204 ± 49 µA (mean ± std) for groups of four electrodes and 91 ± 25 µA for groups of nine electrodes. Saccades to electrically-evoked percepts using groups of nine electrodes showed that the animal could discriminate spatially distinct percepts with groups having an average separation of 1.6 ± 0.3 mm (mean ± std) in cortex and 1.0° ± 0.2° in visual space. Significance. These results demonstrate chronic perceptual functionality and provide evidence for the feasibility of a cortically-based vision prosthesis for the blind using penetrating microelectrodes.
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Affiliation(s)
- T S Davis
- Department of Bioengineering, University of Utah, UT, USA
| | - R A Parker
- Interdepartmental Program in Neuroscience, University of Utah, UT, USA
| | - P A House
- Department of Neurosurgery, University of Utah, UT, USA
| | - E Bagley
- Department of Bioengineering, University of Utah, UT, USA
| | - S Wendelken
- Department of Bioengineering, University of Utah, UT, USA
| | - R A Normann
- Department of Bioengineering, University of Utah, UT, USA
- Department of Ophthalmology and Visual Sciences, University of Utah, UT, USA
| | - B Greger
- Department of Bioengineering, University of Utah, UT, USA
- Department of Ophthalmology and Visual Sciences, University of Utah, UT, USA
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Torab K, Davis TS, Warren DJ, House PA, Normann RA, Greger B. Multiple factors may influence the performance of a visual prosthesis based on intracortical microstimulation: nonhuman primate behavioural experimentation. J Neural Eng 2011; 8:035001. [PMID: 21593550 DOI: 10.1088/1741-2560/8/3/035001] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
We hypothesize that a visual prosthesis capable of evoking high-resolution visual perceptions can be produced using high-electrode-count arrays of penetrating microelectrodes implanted into the primary visual cortex of a blind human subject. To explore this hypothesis, and as a prelude to human psychophysical experiments, we have conducted a set of experiments in primary visual cortex (V1) of non-human primates using chronically implanted Utah Electrode Arrays (UEAs). The electrical and recording properties of implanted electrodes, the high-resolution visuotopic organization of V1, and the stimulation levels required to evoke behavioural responses were measured. The impedances of stimulated electrodes were found to drop significantly immediately following stimulation sessions, but these post-stimulation impedances returned to pre-stimulation values by the next experimental session. Two months of periodic microstimulation at currents of up to 96 µA did not impair the mapping of receptive fields from local field potentials or multi-unit activity, or impact behavioural visual thresholds of light stimuli that excited regions of V1 that were implanted with UEAs. These results demonstrate that microstimulation at the levels used did not cause functional impairment of the electrode array or the neural tissue. However, microstimulation with current levels ranging from 18 to 76 µA (46 ± 19 µA, mean ± std) was able to elicit behavioural responses on eight out of 82 systematically stimulated electrodes. We suggest that the ability of microstimulation to evoke phosphenes and elicit a subsequent behavioural response may depend on several factors: the location of the electrode tips within the cortical layers of V1, distance of the electrode tips to neuronal somata, and the inability of nonhuman primates to recognize and respond to a generalized set of evoked percepts.
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Affiliation(s)
- K Torab
- Department of Bioengineering, University of Utah, UT, USA
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Middlebrooks JC, Snyder RL. Intraneural stimulation for auditory prosthesis: Modiolar trunk and intracranial stimulation sites. Hear Res 2008; 242:52-63. [DOI: 10.1016/j.heares.2008.04.001] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/29/2008] [Revised: 03/11/2008] [Accepted: 04/02/2008] [Indexed: 11/30/2022]
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