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Modeling the Auditory Pathway

School of Industrial Engineering Department of Computer Science Purdue University. Modeling the Auditory Pathway. SERC Showcase, Motorola Labs, Schaumburg, IL , June 7-8, 2006 Sponsor: National Science Foundation. Research Advisor: Aditya Mathur. Graduate Student: Alok Bakshi. Objective.

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Modeling the Auditory Pathway

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  1. School of Industrial Engineering Department of Computer Science Purdue University Modeling the Auditory Pathway SERC Showcase, Motorola Labs, Schaumburg, IL, June 7-8, 2006 Sponsor: National Science Foundation Research Advisor: Aditya Mathur Graduate Student: Alok Bakshi

  2. Objective To construct and validate a model of the auditory pathway to understand the effect of various treatments on children with auditory disorders.

  3. Background and Problem • Children with some forms of auditory disorders are unable to discriminate rapid acoustic changes in speech. • It has been observed that “auditory training” improves the ability to discriminate and identify an unfamiliar sound. • Computational model desired to reproduce this observation. • A validated model would assist in assessing the impact of disorders in the auditory pathway on brainstem potential. This would be useful for diagnosis. [This appears related to fault diagnosis and tolerance in software systems. It might have an impact on the design of redundant software systems.]

  4. Methodology • Study physiology of the auditory system. • Simulate the auditory pathway by constructing new models, or using existing models, of individual components along the auditory pathway. • Validate the model against experimental results pertaining to the auditory system. • Mimic experimental results of auditory processing tasks in children with disabilities and gain insight into the causes of malfunction. • Experiment with the validated model to assess the effects of treatments on children with auditory/learning disabilities.

  5. Characteristics of our approach • Systems, holistic, approach. • Detailed versus aggregate models. • Explicit modeling of inherent anatomical and physiological parallelism.

  6. Progress • Synaptic model is implemented for connection between two neurons • Following (existing) models incorporated for the simulation of the Auditory pathway • Phenomenological model for the response of Auditory nerve fibers • Computational model of the Cochlear Nucleus Octopus Cell

  7. Brainstem Auditory Evoked Potential Normal children Language impaired children http://www.iurc.montp.inserm.fr/cric/audition/english/audiometry/ex_ptw/voies_potentiel.jpg http://www.iurc.montp.inserm.fr/cric/audition/english/audiometry/ex_ptw/e_pea2_ok.gif

  8. Octopus Cell model by Levy et. al. • Models of other cells being implemented Auditory Nerve fiber model by Zhang et. al. Modeling the Auditory Pathway

  9. (Zhang et al., 2001) (Heinz et al., 2001) (Bruce et al., 2003) Model of the Auditory Neuron

  10. Cochlear Nucleus • Consist of 13 types of cells • Single cell responses differ based on • # of excitatory/inhibitory inputs • Input waveform pattern Input tone Onset response Buildup response

  11. AN discharge rate Time Octopus Cell discharge rate Latent period Time Octopus Cell Octopus Cell Receives excitatory input from 60-120 AN fibers

  12. Schematic of a typical Octopus Cell • Representative Cell • Receives 60 AN fibers with 1.4 - 4 kHz CF • Majority of input from high SA fibers, medium SA fibers denoted by superscript ‘m’ http://www.ship.edu/~cgboeree/neuron.gif

  13. Model Simplifications • Four dendrites replaced by a single cylinder • Active axon lumped into soma • Synaptic transmission delay taken as constant 0.5 ms • Compartmental model employed with • 15 equal length dendritic compartments • 2 equal length somatic compartments

  14. Soma Dendrite Octopus Cell Model 2 somatic compartments and 15 dendritic compartments modeled by the same circuit with different parameters Different number of dendritic compartments depending on number of synapses with AN fibers

  15. Outside Iext IK INa IL C K+ ion channel gK gNa gL VK VNa VL Inside ( At potential V ) http://personal.tmlp.com/Jimr57/textbook/chapter3/images/pro5.gif Hodgkin Huxley Model m, n and h depend on V

  16. Hodgkin Huxley Model (contd.) http://www.bbraunusa.com/stimuplex/graphics/low_speed_nerve.jpg

  17. Next Step • Implement model of Octopus Cell and connect it with AN fiber’s model • Implement models of all cells of Cochlear Nucleus and connect them through synapse models • Find out the response of Cochlear Nucleus as a whole with different input waveform signals. • Relation to SE?

  18. References • Drawing/image/animation from "Promenade around the cochlea" <www.cochlea.org> EDU website by R. Pujol et al., INSERM and University Montpellier • Gunter E. and Raymond R. , The central Auditory System’ 1997 • Kraus N. et. al, 1996 Auditory Neurophysiologic Responses and Discrimination Deficits in Children with Learning Problems. Science Vol. 273. no. 5277, pp. 971 – 973 • Levy et. al. 1997 A computational model of the cochlear nucleus octopus cell, Acoustical Society of America [S0001-4966(97)00807-2] • Purves et al, Neuroscience 3rd edition • P. O. James, An introduction to physiology of hearing 2nd edition • Tremblay K., 1997 Central auditory system plasticity: generalization to novel stimuli following listening training. J Acoust Soc Am. 102(6):3762-73

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