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Research Interests


I am interested in understanding the brain functions involved in restored hearing by cochlear implants (CI). Results from investigations into how the brain processes acoustic and electric signals may be instrumental in guiding new CI technology improvements.

 


Current Projects


Cortical Responses to Cochlear Implant Stimulation in Awake Marmoset

Cochlear implants are widely used to provide auditory sensation to hearing impaired individuals.  The success and limitations of a cochlear implant (CI) rely on the ability (or inability) of the central auditory system to adequately process and interpret electric stimuli delivered to the cochlea. However, such mechanisms are not yet fully understood.  We have developed a new non-human primate model for CI research:  the common marmoset (Callithrix jacchus).   A limitation of previous cortical neurophysiology studies of cochlear stimulation has been the use of anesthetized preparations which has been shown to alter auditory cortex responses in hearing subjects. In the present study, we investigate single-unit responses to time-varying acoustic and electric signals in auditory cortex of the awake marmoset.

 

Characterization of Marmoset Temporal Bone: A Cochlear Implant Feasibility Study

The marmoset is a valuable non-human primate model for studying auditory-vocal interactions and neural processing of vocal communication sounds.  It is also well suited for investigating neural mechanisms related to cochlear implants. The purpose of this study was to characterize marmoset temporal bone anatomy and investigate the feasibility of implanting a multi-channel intracochlear electrode into the marmoset scala tympani.  Micro computed tomography (microCT) was used to create high resolution images of the marmoset temporal bone.  Cochlear fluid spaces, middle ear ossicles and the surrounding temporal bone was reconstruction in three-dimensional space.  Given cochlear dimensions, a compatible multi-channel implant electrode was identified and tested in the marmoset.  Our study provides anatomical data for the middle and inner ear of the marmoset, and suggests the potential of the marmoset as a new non-human primate model for cochlear implant research.

 


Publications and Presentations

 

Research papers:


Johnson LA, Della Santina CC, Wang X. Temporal bone characterization and cochlear implant feasibility in the common marmoset (Callithrix jacchus). Hear Res. 2012 Aug;290(1-2):37-44.

 

L. Johnson, A. Gupta, D. Akin, A. Ghafoor, R. Bashir, 2006, “Characterization of vaccinia virus particles using microscale silicon cantilever resonators and atomic force microscopy ,” Journal of Sensors and Actuators Chemical B, Vol 115/1 pp 189-197



Abstracts:


Johnson, LA, Della Santina, CC, Wang, X. “Comparison between single neuron responses to cochlear implant and acoustic stimulation in auditory cortex of awake primate.” Society for Neuroscience, Washington D.C., Nov 2011


Johnson, LA, Della Santina, CC, Wang, X.  “Cortical representations of time-varying cochlear implant stimulation in awake primate.”  Conference on Implantable Auditory Prosthesis (CIAP), Asilomar, CA, July 2011 (Awarded Student Travel Award)


Johnson, LA, Della Santina, CC, Wang, X.  “Neural responses to cochlear implant stimulation in auditory cortex of awake marmoset.”  Association for Research in Otolaryngology (ARO) Annual Midwinter Meeting, Baltimore, MD, Feb 2011


Johnson, LA, Della Santina, CC, Wang, X.  “Cortical responses to cochlear implant stimulation in the awake marmoset.”  Society for Neuroscience, San Diego, CA, Nov 2010


Johnson, LA, Della Santina, CC, Wang, X.  “Cortical single-unit responses to cochlear implant stimulation in the awake marmoset.”  Objective Measures in Auditory Implants 6th International Symposium, St. Louis, MO, Sept 2010 (Awarded Student Travel Award)


Johnson, LA, Della Santina, CC, Wang, X.  “Developing a new vocalizing non-human primate model for cochlear implant research.”  Society for Neuroscience, Chicago, IL, Oct 2009 (poster)

 

Johnson, LA, Della Santina, CC, Wang, X.  “Developing a new non-human primate model for cochlear implant research.”  Conference on Implantable Auditory Prosthesis (CIAP), Lake Tahoe, CA, July 2009 (poster)

 

Johnson, LA, Wang, X.  “Characterization of the marmoset monkey temporal bone:  A cochlear implant feasibility study.”  Association for Research in Otolaryngology (ARO) Annual Midwinter Meeting, Baltimore, MD, Feb 2009 (poster)

 

N. Davidovics, N. Bhanpuri, L. Johnson, G. Colon, C. Smith, A. Wong. "NETI: the neuroengineering training initiative." IEEE/EMBS conference on Neural Engineering, May 2007 (poster)

 

Stekel, SF, Johnson, LA, Tradup, DJ, Walz-Flannigan, AI, Hangiandreou NJ. Development, Implementation, and Initial Use of a Comprehensive System for Automated Quality Control of Diagnostic Ultrasound Scanners. SIIM, Providence, RI, 2007 (abstract)


Johnson, LA, Thoroughman, KA.  “Effect of movement speed on motor adaptation to transient force pulses” Annual Washington University Neuroscience Retreat, Oct 2005. (poster and talk)

 

Johnson, LA, Thoroughman, KA.  “Effect of movement speed on motor adaptation to transient force pulses” Washington University Undergraduate Research Symposium, Nov 2005. (talk)

 

Johnson, L, Gupta A, Davila, A, Akin, D, and Bashir, R, “Virus Particle Mass Detection Using Silicon Cantilever Micro-resonators.” Biomedical Engineering Society Annual Meeting, Oct 2004. (poster)


Johnson, L, Gupta A, Davila, A, Akin, D, and Bashir, R, “Virus Particle Mass Detection Using Silicon Cantilever Micro-resonators.” Research Experience for Undergraduates Conference Proceedings, pg VII,             Aug 2004. (talk)


Johnson, LA and Anderson CC, Kellogg DK.  “Bouguer gravity anomaly in Northeast Iowa.”  Upper Iowa Conference for Undergraduate Research, April 2004 (poster)

 




Contact Info

Luke Johnson

720 Rutland Ave

Traylor 412

Baltimore MD 21205

luke.johnson AT jhu.edu


Luke Johnson

B.A., Physics & Spanish,  Luther College, Decorah IA
B.S., Biomedical Engineering, Washington University in St Louis, St Louis MO
Email:  luke.johnson AT jhu.edu
LinkedIn profile
http://www.linkedin.com/pub/luke-johnson/40/209/402shapeimage_10_link_0
 
  1. Paper published in Hearing Research (cover): Johnson, Della Santina and Wang, Temporal bone characterization and cochlear implant feasibility in the common marmoset (Callithrix jacchus)(2012) [Web]


  2. Paper published Journal of Neurophysiology: Zhou and Wang, Level dependence of spatial processing in the primate auditory cortex (2012) [Web]


  3. Paper published in Journal of Neuroscience:   Eliades and Wang. Neural correlates of the lombard effect in primate auditory cortex (2012) [Web]


  4. Other recent publications

  5. Complete publication list


  1. JHU

  2. JHU BME Department

  3. JHU Center for Hearing and Balance