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SUMMARY:Multi-species studies of vestibular implants
DTSTART:20130516T100000
DTEND:20130516T110000
DTSTAMP:20260528T140032Z
UID:9477c3493911d84a13da8ea5ce9b358eecc4ae077b6b8c082c36178a
CATEGORIES:Conferences - Seminars
DESCRIPTION:Prof. Daniel M Merfeld\, Jenks Vestibular Physiology Laborato
 ry\, Otology and Laryngology\, Harvard Medical School\, Boston.\nDisorders
  of the peripheral vestibular system are relatively common and often resul
 t in severely impaired mobility\, blurred vision and debilitating attacks 
 of vertigo and motion sickness.  Presently\, little can be done to resolv
 e these symptoms when they are chronically present. Early research in the 
 area of vestibular neuroprosthetics alongside the success of the cochlear 
 implant\, provides hope that providing motion cues via electrical stimulat
 ion may eventually help some patients suffering severe vestibular impairme
 nt.  Conceptually\, vestibular prostheses are similar to cochlear implant
 s and consist of 4 principal elements:  a power source\, motion sensors\,
  a microcontroller\, and an electrode.  We have developed and tested a ve
 stibular prosthesis that senses yaw angular head velocity and uses this in
 formation to modulate the rate of current pulses applied to the vestibular
  nerve via an electrode chronically. \nThis device has been tested in thr
 ee species.  In squirrel monkeys\, the lateral canals were plugged bilate
 rally and our prosthesis was secured to the head with the angular velocity
  sensor parallel to the axis of the lateral canals.  The stimulating elec
 trode was placed near the ampullary nerve of one lateral canal.  When rot
 ated in the dark\, the animals responded with an appropriate horizontal ve
 stibulo-ocular reflex (VOR)\, which adapted over time\, providing evidence
  that the CNS was utilizing the information provided electrically.  Data 
 also show that the artificial rotational cue provided by the prosthesis is
  combined with normal sensory cues measuring the relative orientation of g
 ravity.  In another experiment\, guinea pigs were provided chronic consta
 nt-rate stimulation and responded with a brisk nystagmus that adapted away
  after about a day.  When the stimulation was removed\, a brisk nystagmus
  in the opposite direction was measured\, again lasting about a day.  The
 se findings demonstrate adaptation to constant-rate stimulation.  When th
 e stimulation was alternately turned on and off weekly\, the nystagmus res
 ponse began to decay more rapidly\, eventually decaying just a few seconds
  after the device was turned on or off.  This indicates that\, with repet
 itive application of chronic stimulation\, the animal learned to adapt rap
 idly to the present state (on or off) of stimulation.  Such “switching
 ” will be important for users of vestibular prosthetics so they don’t 
 feel disoriented when they remove the device to sleep\, shower\, etc.  In
  studies with rhesus monkeys\, we inserted an electrode into the right pos
 terior canal.  We have found that that the application of prosthetic stim
 ulation to a posterior canal yields perceived tilt illusions consistent wi
 th predictions for normal semicircular canal stimulation.  While all of t
 his preliminary work suggests clinical potential\, many questions remain u
 nanswered\, and many challenges must be addressed prior to clinical use.
LOCATION:SV 1717A http://plan.epfl.ch/?room=SV%201717A
STATUS:CONFIRMED
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