Julie A Bierer
University Of Washington
Project start date: 2012-02-01
Project end date: 2017-01-31
Sponsored Links Excellgen http://Excellgen.com
Grants awarded to Julie A Bierer
Channel Interaction In Cochlear Implant Subjects
Julie A Bierer
University Of California San Francisco 3333 California St., Ste 315 San Francisco, Ca 941430962
Grant 5F32DC005883-03 from National Institute On Deafness And Other Communication Disorders IRG: ZDC1
Abstract: This study will examine both physical and neural-perceptual channel interactions that occur with stimulation of multiple channel cochlear implants. Specifically, the effects of channel interactions on percepts of stimulus detection thresholds and loudness estimation for dual-channel stimulation will be examined and quantified. In addition, a battery of speech recognition tests will be performed and correlated with the above mentioned measures of channel interaction. For all of these measurements, the degree of channel interaction will be manipulated by controlling the spatial extent of the electrical current configuration delivered to each of several cochlear implant channels. Cochlear electrode configurations will consist of monopolar (MP), bipolar (BP) with adjacent active and return electrodes within the scala tympani, and tripolar (TP) with one active electrode and two flanking return electrodes. The overall hypotheses to be tested are that channel interactions will be reduced when a spatially restricted electrical current configuration is employed and that reduction in channel interactions should lead to enhanced subject performance on speech recognition. The results of these studies could influence the development of future cochlear implant electrodes and speech processing strategies, ideally, leading to improved performance for most cochlear implant subjects.
Keywords: cochlear implant, psychophysics, sound perception, speech recognition, auditory discrimination, auditory feedback, auditory threshold, cochlea, electrode, neural information processing, clinical research, computer human interaction, human subject, medical implant science, patient oriented research, postdoctoral investigator
Project start date: 2002-09-04
Project end date: 2005-09-03
5F32DC005883-03 (2004): $48928
5F32DC005883-02 (2003): $46420
1F32DC005883-01 (2002): $38320
PROBING THE COCHLEA WITH PARTIAL TRIPOLAR STIMULATION IN COCHLEAR IMPLANTEES
Julie A Bierer, Assistant Professor
University Of Washington, Office Of Sponsored Programs, Seattle, Wa 98195-9472
Grant 5R03DC008883-02 from National Institute On Deafness And Other Communication Disorders
Abstract: Cochlear implants are highly successful neural prostheses that enhance or restore hearing to the severely hearing impaired. However, performance varies considerably among cochlear implant listeners, particularly in noisy environments and for spectrally complex stimuli like music. Pathology and imaging studies suggest that two sources of performance variability are the distribution of surviving spiral ganglion neurons and their distance from individual CI electrodes. The objective of the proposed study is to develop clinically useful procedures to determine non-stimulable regions of the cochlea. The resulting functional maps could guide the production of patient-specific sound processing strategies, leading to improvements in the auditory ability of cochlear implant listeners. Three types of psychophysical and electrophysiological experiments will be conducted to identify the location of low functioning cochlear implant channels. All experiments will use a novel electrode configuration, partial tripolar, to activate restricted populations of neurons, analogous to the use of narrowband stimuli for assessing low functioning acoustic dead regions in hearing impaired listeners. The partial tripolar configuration is a hybrid between the broad monopolar and narrow tripolar configurations, in which the fraction of current that flows to two flanking electrodes can be adjusted to change the spread of current in the cochlea. In the first experiment, detection thresholds will be measured across the implant array as the partial tripolar fractional current varies. Low functioning channels will be inferred from channels with relatively high thresholds when the current field is narrow and the change in threshold with fractional current will provide information about the spatial extent of the functional deficit. In the second experiment, psychophysical tuning curves will be obtained using a forward masking procedure to provide a more detailed assessment of cochlear activation. Similar to the application of tuning curves to diagnose acoustic dead regions, the widths and tip shifts of the tuning curves will be measured as a way to identify low functioning cochlear implant channels. In the third experiment, evoked potentials will be recorded. Evoked potential thresholds and amplitude growth functions will be directly compared to psychophysical thresholds and tuning curves obtained with different partial tripolar current fractions. A significant correlation will suggest that the evoked potential procedure, which is a clinically practical technique, can detect low functioning channels. Ultimately, the findings of this study may lead to the development of a patient-specific mapping procedure that can be used clinically. Over 60,000 people with severe hearing loss have been fitted with cochlear implants to restore some auditory capabilities. Identifying low functioning cochlear implant channels in the proposed study could lead to the enhancement of speech and music perception in these patients
Keywords: Acoustic; Acoustic Nerve; Acoustics; Auditory; Auditory Prosthesis; Brain Stem; Brainstem; Clinic; Cochlea; Cochlear Implants; Cochlear Organ; Cochlear Prosthesis; Cochlear structure; Complex; Cranial Nerve Eight; Cranial Nerve VIII; Detection; Development; Diagnosis; Eighth Cranial Nerve; Electrodes; Environment; Evoked Potentials; Ganglion of Corti; Generalized Growth; Growth; Hair Cells, Inner; Hearing; Hearing Loss; Hybrids; Hypoacuses; Hypoacusis; Image; Implant; Individual; Inner Hair Cells; Lead; Location; Loudness; Maps; Masks; Measurement; Measures; Methods; Methods and Techniques; Methods, Other; Music; Musics; Nerve Cells; Nerve Unit; Neural Cell; Neurocyte; Neurons; Pathology; Patients; Pb element; Perception; Performance; Pilot Projects; Population; Procedures; Process; Production; Psychology, Physiologic; Psychology, Physiological; Psychophysiological; Psychophysiology; Research; Resolution; Shapes; Sound; Sound - physical agent; Source; Speech; Spiral Ganglion; Stimulus; Structure of spiral ganglion; Techniques; Testing; Tissue Growth; VIIIth Cranial Nerve; Vestibulocochlear Nerve; Width; auditory nerve; base; experiment; experimental research; experimental study; hearing impairment; hearing perception; heavy metal Pb; heavy metal lead; imaging; improved; interest; neural prosthesis; neural prosthetic; neuronal; novel; ontogeny; pilot study; psycho-physiological; research study; response; sound; sound perception; speech processing; spiral ganglion
Project start date: 2008-06-01
Project end date: 2011-05-31
Budget start date: 1-JUN-2009
Budget end date: 31-MAY-2010
PFA/PA: PAR-07-287
5R03DC008883-02 (2009): $156000