1. Anthony J Greene1 AUDITORY PATHWAYS & HEARING

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3. 3 Auditory Projections

4. Anthony J Greene4 Tonotopic Organization of A1

5. Anthony J Greene5 Medial Geniculate Nucleus Auditory Cortex Inferior Colliculus Cochlear Nucleus Left Auditory NerveSuperior Olive Right Auditory Nerve

6. 6 Auditory Pathways Medial Geniculate Nucleus Auditory Cortex Inferior Colliculus Cochlear Nucleus Left Auditory Nerve Superior Olive Right Auditory Nerve

7. Anthony J Greene7 Auditory Pathways Auditory Nerve - Axons from hair cells Cochlear Nucleus - Sends information from the auditory nerve to the Superior Olive and to the Inferior Colliculus Superior Olive - Analogous to the Optic Chiasm - information from both ears crosses over to be sent to both hemispheres Inferior Colliculus - Analogous to the Superior Colliculus for vision - Orienting and reflexive localization -- recent studies show multimodal neurons in the colliculus which share visual and auditory information for orientation movements Medial Geniculate Nucleus (MGN) Relays information from the SO to A1

8. Anthony J Greene8 Range of Hearing 20 50 100 200 500 1000 2000 5000 10000 Frequency (Hz)

9. Anthony J Greene9 Range of Hearing Range of speech sounds 20 50 100 200 500 1000 2000 5000 10000 Frequency (Hz)

10. Anthony J Greene10 Audiogram

11. Anthony J Greene11 Audiogram critical for certain consonants

12. Anthony J Greene12 Hearing Loss Conduction Deafness - any damage to the middle ear which impairs hearing Nerve Deafness or Presbicusis- Effects High Frequencies - Less elasticity in the Basilar membrane - Loss of nutrients to cochlea - Cumulative effects of noise Noise Exposure - Effects High Frequencies - Both Sudden and prolonged exposure When high Frequency hearing is impaired speech perception becomes increasingly difficult

13. Anthony J Greene13 Auditory Impairments, Sensory Substitution & Treatments

14. Anthony J Greene14 Types of Impairment 1.Conduction Deafness 2.Nerve Deafness 3.Cortical Deafness

15. Anthony J Greene15 Conduction Deafness Anything up to but not including the cochlea 1.Obstructions 2.Damage

16. Anthony J Greene16 Treating Conduction Deafness Remove Obstruction Repair Eardrum Repair Ossicles Open Eustacian Tube

17. Anthony J Greene17 Nerve Deafness Damage to the Cochlea, Or Path to Cortex 1. Cilia or Hair Cells 2. Basilar Membrane 3. Auditory Nerve 4. Olive 5. Auditory Tract 6. Inferior Colliculus 7. MGN of Thalamus 8. Auditory Projections

18. Anthony J Greene18 Causes of Type I Nerve Deafness Presbycusis – Old Ear -- High Frequency hearing loss Noise Induced Hearing Loss: Also effects high frequencies – Damage to cilia or Bassilar membrane -- Tinitus Infection of Cochlea – Damage to cilia Menier’s Disease: Excessive fluid pressure in Cochlea damages Organ of Corti.

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20. 20 Treating Type I Nerve Deafness Cochlear Implant

21. Anthony J Greene21 Cochlear Implant: Internal

22. Anthony J Greene22 Cochlear Implant Recall that the cochlea is coiled And that the basillar membrane selects frequencies The electrode has multiple stimulation points that selectively activate nerves at the appropriate places

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27. Anthony J Greene27 Nerve Deafness Damage to the Cochlea, Or Path to Cortex 1. Cilia or Hair Cells 2. Basilar Membrane 3. Auditory Nerve 4. Olive 5. Auditory Tract 6. Inferior Colliculus 7. MGN of Thalamus 8. Auditory Projections

28. Anthony J Greene28 Causes of Type II Nerve Deafness Degenerative nerve disease Congenital disorder Infection Stroke Trauma

29. Anthony J Greene29 Treating Type II Nerve Deafness No cure at present Stem cells research is designed to allow new nerve growth in damaged areas. Has already worked with Parkinson’s and Tourrette’s Should work for vision, audition, Alzheimers, Epilepsy, stroke, etc.

30. Anthony J Greene30 Summary of Nerve Deafness Caused by damage between cochlea and cortex Cochlear Implants Stem Cell Research

31. Anthony J Greene31 Sensory Substitution ASL: Closed Captioning Foundation