Primary Research Area:

Biomedical Engineering including Bioelectric Stimulation, Cochlear Implants, Image Processing and Analysis, Implantable Electronics, Mathematical Modeling, Medical Instrumentation, Neurobiology

Communications and Signal Processing including Digital Signal Processing / Multidimensional Signal Processing

Intelligent Systems and Bioengineering including Medical Devices

Research Interests:

My primary research focuses on the basic science, engineering design and clinical application of cochlear prostheses. A cochlear prosthesis is a medical device designed to restore functional hearing in the severely and profoundly hearing impaired. It typically consists of an externally-worn sound processor that controls a multichannel stimulator that is implanted beneath the scalp behind the ear. The stimulator passes electrical currents to a multicontact electrode array implanted into the inner ear (cochlea). These currents pass into the tissue and stimulate surviving auditory neurons which in turn elicit sounds for the implant subject. The sound processor analyzes incoming speech information to produce pattern activity that is perceived as speech.

While speech reception performance can be phenomenal in some implanted patients, there is wide variation in outcome across the general patient population. Understanding the basis of this variability may provide a key to improving device performance for all users. My research seeks this goal through a broad, multidisciplinary approach to combine high-resolution CT images of the implanted ear, intracochlear evoked potential physiological responses, and psychophysical measures to infer the anatomical and pathophysiological conditions (e.g., electrode placement amd insertion depth, density and pattern of neural survival, electroanatomy of the cochlea, etc) in individual patients that may limit their performance. These inferences are drawn primarily from computational models of electrical fields and neural responses which are developed for each individual subject based on the imaging and electrophysiological data. Knowledge of these conditions in individual patients can directly influence the design and fitting of custom speech processors that may optimally provide speech information to the individual. This information is also applied to the general improvement of assessment tools, fitting protocols, electrode designs and speech processor platforms.

A second area of active research is the measurement of electrical artifact signals from the scalp of cochlear implant subjects for the purpose of (1) monitoring device function (i.e., Is the implanted device working as it should?), (2) determining the pathways by which current flows into and out of the cochlea depending on various stimulation conditions, and (3) identifying techniques to minimize the deleterious effects of electrical artifact signals in measuring evoked neural responses in the brainstem and cortex.

A third area of active research is the development of a rat cochlear slice model of electrical stimulation so that fundamental assumptions regarding the impedance properties of cochlear tissue at high frequencies may be tested.

A fourth area of active work is the development of specialized biopotential amplifiers and recording systems for measuring low-level biological responses either immediately following or during high-level electrical stimulation.

Students are encouraged to contact me to learn more about these and other activities. All inquires are welcome whether it be curiosity about the subject matter and/or the possibility of working on a lab project.

Education:

BS in Electrical Engineering (Co-op), Georgia Tech, Atlanta
PhD in Neurobiology, UNC-Chapel Hill

Recent Publications:

1. Finley C, Herrmann B, and Eddington D (2004) Wide-bandwidth amplifier for recording scalp potentials genertated by cochlear implants. Quarterly Progress Report #11, Speech Processors for Auditory Prostheses, Contract N01-DC-2-1001, NIDCD, NIH. [ Related link ]
2. Finley C, Herrmann B, and Eddington D(2004) Channel interactions in cochlear implant subjects. Quarterly Progress Report #10, Speech Processors for Auditory Prostheses, Contract N01-DC-2-1001, NIDCD, NIH. [ Related link ]
3. Herrmann B, Eddington D, and Finley C (2003) Measuring channel interactions in cochler implant subjects using intracochlear eveoked responses. Quarterly Progress Report #8, Speech Processors for Auditory Prostheses, Contract N01-DC-2-1001, NIDCD, NIH. [ Related link ]
4. Finley C, Christopher P, Eddington D, and Herrmann B (2003) Monitoring cochlear implant device function using scalp artifact measures. Quarterly Progress Report #7, Speech Processors for Auditory Prostheses, Contract N01-DC-2-1001, NIDCD, NIH. [ Related link ]
5. Eddington D, Herrmann B, and Finley C (2002) Recording of intracochlear evoked potentials in cochlear implant subjects. Quarterly Progress Report #2, Speech Processors for Auditory Prostheses, Contract N01-DC-2-1001, NIDCD, NIH. [ Related link ]
6. Cartee LA, van den Honert C, Finley CC, and Miller RL: (2000) Evaluation of a model of the cochlear neural membrane. I. Physiological measurement of membrane characteristics in response to intrameatal electrical stimulation. Hearing Research 146(1-2): 143-52.
7. van den Honert C, Finley CC, and Xue S (1997) Microstimulation of auditory nerve for estimating cochlear place of single fibers in a deaf ear. Hearing Research 113:140-154.
8. Smith, DW, Finley CC, and van den Honert C (1994) Behavioral and electrophysiological responses to electrical stimulation in the cat. 1. Absolute thresholds. Hearing Research 81:1-10.
9. Wilson BS, Finley CC, Lawson DT, Wolford RD, Eddington DK, and Rabinowitz WM (1991) Better speech recognition with cochlear implants. Nature 352: 236-238.
10. Finley CC, Wilson BS, and White MW (1990): Models of neural responsiveness to electrical stimulation. In Miller JM and Spelman FA (Eds.), Models of the Electrically Stimulated Cochlea, Springer-Verlag, pp. 55-96.

Date of Last Modification: 2/14/2007

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