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Auditory Midbrain Implant

Yoojin Chung, Kenneth E Hancock, Bertrand Delgutte
UNLABELLED: Although bilateral cochlear implants (CIs) provide improvements in sound localization and speech perception in noise over unilateral CIs, bilateral CI users' sensitivity to interaural time differences (ITDs) is still poorer than normal. In particular, ITD sensitivity of most CI users degrades with increasing stimulation rate and is lacking at the high carrier pulse rates used in CI processors to deliver speech information. To gain a better understanding of the neural basis for this degradation, we characterized ITD tuning of single neurons in the inferior colliculus (IC) for pulse train stimuli in an unanesthetized rabbit model of bilateral CIs...
May 18, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Daniel S Pages, Deborah A Ross, Vanessa M Puñal, Shruti Agashe, Isaac Dweck, Jerel Mueller, Warren M Grill, Blake S Wilson, Jennifer M Groh
UNLABELLED: Understanding the relationship between the auditory selectivity of neurons and their contribution to perception is critical to the design of effective auditory brain prosthetics. These prosthetics seek to mimic natural activity patterns to achieve desired perceptual outcomes. We measured the contribution of inferior colliculus (IC) sites to perception using combined recording and electrical stimulation. Monkeys performed a frequency-based discrimination task, reporting whether a probe sound was higher or lower in frequency than a reference sound...
May 4, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Kenneth S Henry, Erikson G Neilans, Kristina S Abrams, Fabio Idrobo, Laurel H Carney
Amplitude modulation (AM) is a crucial feature of many communication signals, including speech. Whereas average discharge rates in the auditory midbrain correlate with behavioral AM sensitivity in rabbits, the neural bases of AM sensitivity in species with human-like behavioral acuity are unexplored. Here, we used parallel behavioral and neurophysiological experiments to explore the neural (midbrain) bases of AM perception in an avian speech mimic, the budgerigar (Melopsittacus undulatus). Behavioral AM sensitivity was quantified using operant conditioning procedures...
April 2016: Journal of Neurophysiology
Mika Sato, Peter Baumhoff, Andrej Kral
UNLABELLED: Electroacoustic stimulation in subjects with residual hearing is becoming more widely used in clinical practice. However, little is known about the properties of electrically induced responses in the hearing cochlea. In the present study, normal-hearing guinea pig cochleae underwent cochlear implantation through a cochleostomy without significant loss of hearing. Using recordings of unit activity in the midbrain, we were able to investigate the excitation patterns throughout the tonotopic field determined by acoustic stimulation...
January 6, 2016: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Andrew D Brown, Heath G Jones, Alan Kan, Tanvi Thakkar, G Christopher Stecker, Matthew J Goupell, Ruth Y Litovsky
Normal-hearing human listeners and a variety of studied animal species localize sound sources accurately in reverberant environments by responding to the directional cues carried by the first-arriving sound rather than spurious cues carried by later-arriving reflections, which are not perceived discretely. This phenomenon is known as the precedence effect (PE) in sound localization. Despite decades of study, the biological basis of the PE remains unclear. Though the PE was once widely attributed to central processes such as synaptic inhibition in the auditory midbrain, a more recent hypothesis holds that the PE may arise essentially as a by-product of normal cochlear function...
November 2015: Journal of Neurophysiology
Georg Berding, Florian Wilke, Thilo Rode, Cathleen Haense, Gert Joseph, Geerd J Meyer, Martin Mamach, Minoo Lenarz, Lilli Geworski, Frank M Bengel, Thomas Lenarz, Hubert H Lim
Considerable progress has been made in the treatment of hearing loss with auditory implants. However, there are still many implanted patients that experience hearing deficiencies, such as limited speech understanding or vanishing perception with continuous stimulation (i.e., abnormal loudness adaptation). The present study aims to identify specific patterns of cerebral cortex activity involved with such deficiencies. We performed O-15-water positron emission tomography (PET) in patients implanted with electrodes within the cochlea, brainstem, or midbrain to investigate the pattern of cortical activation in response to speech or continuous multi-tone stimuli directly inputted into the implant processor that then delivered electrical patterns through those electrodes...
2015: PloS One
Hubert H Lim, Thomas Lenarz
The cochlear implant is considered one of the most successful neural prostheses to date, which was made possible by visionaries who continued to develop the cochlear implant through multiple technological and clinical challenges. However, patients without a functional auditory nerve or implantable cochlea cannot benefit from a cochlear implant. The focus of the paper is to review the development and translation of a new type of central auditory prosthesis for this group of patients that is known as the auditory midbrain implant (AMI) and is designed for electrical stimulation within the inferior colliculus...
April 2015: Hearing Research
Sarah J Offutt, Kellie J Ryan, Alexander E Konop, Hubert H Lim
OBJECTIVE: The inferior colliculus (IC) is the primary processing center of auditory information in the midbrain and is one site of tinnitus-related activity. One potential option for suppressing the tinnitus percept is through deep brain stimulation via the auditory midbrain implant (AMI), which is designed for hearing restoration and is already being implanted in deaf patients who also have tinnitus. However, to assess the feasibility of AMI stimulation for tinnitus treatment we first need to characterize the functional connectivity within the IC...
December 2014: Journal of Neural Engineering
Małgorzata M Straka, Melissa McMahon, Craig D Markovitz, Hubert H Lim
OBJECTIVE: An increasing number of deaf individuals are being implanted with central auditory prostheses, but their performance has generally been poorer than for cochlear implant users. The goal of this study is to investigate stimulation strategies for improving hearing performance with a new auditory midbrain implant (AMI). Previous studies have shown that repeated electrical stimulation of a single site in each isofrequency lamina of the central nucleus of the inferior colliculus (ICC) causes strong suppressive effects in elicited responses within the primary auditory cortex (A1)...
August 2014: Journal of Neural Engineering
Anna R Chambers, Kenneth E Hancock, Kamal Sen, Daniel B Polley
Neurons in sensory brain regions shape our perception of the surrounding environment through two parallel operations: decomposition and integration. For example, auditory neurons decompose sounds by separately encoding their frequency, temporal modulation, intensity, and spatial location. Neurons also integrate across these various features to support a unified perceptual gestalt of an auditory object. At higher levels of a sensory pathway, neurons may select for a restricted region of feature space defined by the intersection of multiple, independent stimulus dimensions...
July 2, 2014: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Benjamin A Rowland, Wan Jiang, Barry E Stein
Detecting and locating environmental events are markedly enhanced by the midbrain's ability to integrate visual and auditory cues. Its capacity for multisensory integration develops in cats 1-4 months after birth but only after acquiring extensive visual-auditory experience. However, briefly deactivating specific regions of association cortex during this period induced long-term disruption of this maturational process, such that even 1 year later animals were unable to integrate visual and auditory cues to enhance their behavioral performance...
May 21, 2014: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
S Muthuraju, M J Nobre, V M N Saito, M L Brandao
Chemical and electrical stimulation of the inferior colliculus (IC) causes defensive behavior. Electrical stimulation of the IC at the escape threshold enhances dopamine (DA) release in the prefrontal cortex. Intra-ventral tegmental area injections of quinpirole at doses that act presynaptically reduce the release of DA in the terminal fields of the mesolimbic system and clearly reduce conditioned fear in several animal models of anxiety. However, little is known about the involvement of DA in the mediation of unconditioned fear, such as the reactivity to acute stressors...
March 7, 2014: Neuroscience
Yoojin Chung, Kenneth E Hancock, Sung-Il Nam, Bertrand Delgutte
Cochlear implant (CI) listeners show limits at high frequencies in tasks involving temporal processing such as rate pitch and interaural time difference discrimination. Similar limits have been observed in neural responses to electric stimulation in animals with CI; however, the upper limit of temporal coding of electric pulse train stimuli in the inferior colliculus (IC) of anesthetized animals is lower than the perceptual limit. We hypothesize that the upper limit of temporal neural coding has been underestimated in previous studies due to the confound of anesthesia...
January 1, 2014: Journal of Neuroscience: the Official Journal of the Society for Neuroscience
Craig A Atencio, Jonathan Y Shih, Christoph E Schreiner, Steven W Cheung
Cochlear implant electrical stimulation of the auditory system to rehabilitate deafness has been remarkably successful. Its deployment requires both an intact auditory nerve and a suitably patent cochlear lumen. When disease renders prerequisite conditions impassable, such as in neurofibromatosis type II and cochlear obliterans, alternative treatment targets are considered. Electrical stimulation of the cochlear nucleus and midbrain in humans has delivered encouraging clinical outcomes, buttressing the promise of central auditory prostheses to mitigate deafness in those who are not candidates for cochlear implantation...
March 2014: Journal of Neurophysiology
Roger Calixto, Behrouz Salamat, Thilo Rode, Tanja Hartmann, Bart Volckaerts, Patrick Ruther, Thomas Lenarz, Hubert H Lim
Ongoing clinical studies on patients recently implanted with the auditory midbrain implant (AMI) into the inferior colliculus (IC) for hearing restoration have shown that these patients do not achieve performance levels comparable to cochlear implant patients. The AMI consists of a single-shank array (20 electrodes) for stimulation along the tonotopic axis of the IC. Recent findings suggest that one major limitation in AMI performance is the inability to sufficiently activate neurons across the three-dimensional (3-D) IC...
2013: PloS One
Thilo Rode, Tanja Hartmann, Peter Hubka, Verena Scheper, Minoo Lenarz, Thomas Lenarz, Andrej Kral, Hubert H Lim
The auditory midbrain implant (AMI) consists of a single shank array (20 sites) for stimulation along the tonotopic axis of the central nucleus of the inferior colliculus (ICC) and has been safely implanted in deaf patients who cannot benefit from a cochlear implant (CI). The AMI improves lip-reading abilities and environmental awareness in the implanted patients. However, the AMI cannot achieve the high levels of speech perception possible with the CI. It appears the AMI can transmit sufficient spectral cues but with limited temporal cues required for speech understanding...
2013: Frontiers in Neural Circuits
Sophia N Kouni, Sotirios Giannopoulos, Nausika Ziavra, Constantinos Koutsojannis
PURPOSE AND BACKGROUND: Acoustic signals are transmitted through the external and middle ear mechanically to the cochlea where they are transduced into electrical impulse for further transmission via the auditory nerve. The auditory nerve encodes the acoustic sounds that are conveyed to the auditory brainstem. Multiple brainstem nuclei, the cochlea, the midbrain, the thalamus, and the cortex constitute the central auditory system. In clinical practice, auditory brainstem responses (ABRs) to simple stimuli such as click or tones are widely used...
November 2013: American Journal of Otolaryngology
B J Allitt, C Benjaminsen, S J Morgan, A G Paolini
OBJECTIVE: Auditory midbrain implants (AMI) provide inadequate frequency discrimination for open set speech perception. AMIs that can take advantage of the tonotopic laminar of the midbrain may be able to better deliver frequency specific perception and lead to enhanced performance. Stimulation strategies that best elicit frequency specific activity need to be identified. This research examined the characteristic frequency (CF) relationship between regions of the auditory cortex (AC), in response to stimulated regions of the inferior colliculus (IC), comparing monopolar, and intralaminar bipolar electrical stimulation...
August 2013: Journal of Neural Engineering
Christine E Parsons, Katherine S Young, Morten Joensson, Elvira Brattico, Jonathan A Hyam, Alan Stein, Alexander L Green, Tipu Z Aziz, Morten L Kringelbach
Infant vocalizations are among the most biologically salient sounds in the environment and can draw the listener to the infant rapidly in both times of distress and joy. A region of the midbrain, the periaqueductal gray (PAG), has long been implicated in the control of urgent, survival-related behaviours. To test for PAG involvement in the processing of infant vocalizations, we recorded local field potentials from macroelectrodes implanted in this region in four adults who had undergone deep brain stimulation...
July 2014: Social Cognitive and Affective Neuroscience
Malgorzata M Straka, Dillon Schendel, Hubert H Lim
While the cochlear implant has successfully restored hearing to many deaf patients, it cannot benefit those without a functional auditory nerve or an implantable cochlea. As an alternative, the auditory midbrain implant (AMI) has been developed and implanted into deaf patients. Consisting of a single-shank array, the AMI is designed for stimulation along the tonotopic gradient of the inferior colliculus (ICC). Although the AMI can provide frequency cues, it appears to insufficiently transmit temporal cues for speech understanding because repeated stimulation of a single site causes strong suppressive and refractory effects...
August 2013: Journal of Neurophysiology
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