Inner Ear Dysfunction

1
Inner Ear Dysfunction

• Upcoming Talk Isabelle Peretz
• Musical Non-musical Brains
• Nov. 22 _at_ 12 noon Lunch
• Rm 2068B South Building

2
Neural Correlates of Stream Segregation

• Summation of cortical response hypothesis
• (DRAW) Will a stimulated area summate with
  another stimulated area on the tonotopic map?
• Tetanic rapid stimulation increases probability
  of summation (Fishman et al., 2001)
• ALTERNATIVELY?
• Lesions of temporal cortex (in and around primary
  auditory cortex) (Peretz and colleagues, 1999
  2001)
• Poster temporal gyrus affects melodic grouping
• Intervals, melodic contours
• Anterior temporal gyrus affects meter
• Rhythmic grouping, temporal combinations

3
Tinnitus It has a certain ring to it (see
Mencher pp. 144-145)

• What is Tinnitus?
• Ringing, buzzing, roaring, clicking experienced
  in one or both ears
• Objective tinnitus
• Audible to a third party
• Stethoscope examination
• Less than 5 of all tinnitus sufferers
• Subjective tinnitus
• Audible only to the patient
• Subjective report
• Approx. 35 of the population (continuous 15)
• Severe in 15 of tinnitus sufferers
• Incidence increases with age hearing loss
• Noise-induced trauma

4
Causes of Tinnitus

• Vibratory
• Acoustic stimulation of cochlea
• Pulsatile tinnitus Rhythmic pulsing, heartbeat
• Leudets tinnitus crackling of involuntary
  muscles
• Jaw neck position
• Clicking tinnitus Clicking sound that may occur
  with serous otitis media
• May be objective or subjective
• Non-vibratory
• Neurochemical changes
• Not traced to acoustic stimulation
• Subjective tinnitus

5
Physiological-subjective tinnitus (Jastreboff,
1990)

• Cochlear causes
• Increased otoacoustic emissions
• Continuous spontaneous firing (4)
• Collapsing tectorial membrane
• Chronic bent inner hair cells
• Tetanic stimulation of auditory system
• Reduced outer hair cell population
• Inability to modulate gain
• Chronic higher sensitivity to background noise
• Hyperacusis chronic oversensitivity (40
  correlation)
• Correlation with Sensori-neural hearing loss

6
Higher-level Tinnitus(Lockwood et al., 1998)

• Persistent symptoms after transection of auditory
  pathway
• Cortical phenomenon?
• fMRI evidence (blood flow)
• Typical auditory stimulation bilateral
  activation
• Tinnitus causes unilateral activation
• Modulation of tinnitus has unilateral effects
• Neurochemical change in midbrain or cortex may
  contribute to tinnitus

7
Summary Treatments

• Variety of contributing pathologies
• Physical
• Pinched blood vessel, loud-noise exposure,
  muscular activity, stress
• Toxicity
• Foods (allergic reactions), quinine, aspirin,
  cigarettes, alcohol, caffeine
• Multiple causes
• Treatments
• Jaw position
• Cutting cochlear nerve (50 effective)
• Masking noise
• Effectiveness of noise suggests no dementia
• Hearing Aid use
• Tinnitus retraining therapy
• Habituation to tinnitus sound to reduce
  aversiveness