Lecture 18

  1. Describe the tree types of sensory input:
    • vestibular
    • visual
    • somatosensory
  2. ______: Can be viewed as a motor skill that emerges from the interaction of multiple systems. Describe the three components.
    • Balance
    • Steadiness, Symmetry, Dynamic stability
  3. ______ system: Provides information concerning gravity, rotation and acceleration. Contributes to integration of arousal,conscious awareness of the body via connections with vestibular cortex and reticular formation
    Vestibular system
  4. Influence from the ________ pathway mediate nausea and vomiting.
  5. ______ system: allows for gaze and postural stability; sense of orientation; detection of linear and angular acceleration.
    Vestibular system
  6. ______ ______ _____: detects and relays info about head angular and linear velocity to central processing system. Orients the head with respect ot gravity.
    Peripheral sensory apparatus
  7. _____ _____ ____: processes info in conjunction with other sensory inputs for position and movement of head in space.
    central processing system
  8. ____ ____ ____: generates compensatory eye movements and compensatory body movements during head and postural adjustments.
    motor output system
  9. The peripheral apparatus is composed of
    • Membranous labyrinth
    • semicircular canals
    • otolith organs
  10. ______ ______: responsible for angular acceleration and ampulla contains sensory epithelium.
    Semicircular Canal
  11. The spatial arrangement of the 6 SSC causes __ coplanar pairings. What are they?
    3: R and L lateral; L anterior and R posterior; L posterior and R anterior; R and L horizontal
  12. The 3 coplanar pairings all for the ___-____ arrangement.
    Push-pull arrangement
  13. What are the 3 advantages of SSC coplanar pairing.
    • sensory redundancy
    • common mode rejection/mode
    • assist in compensation for sensory overload
  14. What are the three structures of the Otoliths (utricle and saccule):
    • maculae
    • otolithic membrane
    • otoconia
  15. _____ function: respond to linear head motion on acceleration; static tilt; two organs respond to respective accelerations or tilts in their respective planes.
  16. _____: vertical orientation of maculae. linear accelerations/deceleration in vertical plane. Tilting head toward lateral plane. Sensitive to low frequency vibration.
  17. _____: horizontal orientation of maculae. Respond to acceleration/deceleration in horizontal plane. Head movements toward ventral or dorsal planes.
  18. What are the two types of hair cells?
    What are there functions?
    • kinoclium and stereocilia
    • Sensory structures for the peripheral end organs (maculae and ampulla)
    • Hyperpolarized or depolarized depending upon the direction of deflection of the stereocilia (movement of stereocilia towards the kinocilium causes depolarization of the hair cell)
    • Affect the firing rate of the primary vestibular afferents to the brainstem
  19. _____ of macula: serves as structural landmark. Contains otoconia arranged in narrow trenches, dividing each otolith. Orientation of the hair cells change over the course of the macula. Allows otoliths to have multidirectional sensitivity.
  20. ____ ____ ____:
    • Vestibular nerve and vestibular nuclei have anormal resting firing rate (70-100 cycles/sec)
    • Baseline firing rate present without headmovement• Tonic firing is equal in both sides; if not, asense of motion is felt e.g., vertigo, tilt,impulsion, spinning
    • Excitation and inhibition of the vestibularsystem can then occur from stimulation of thehair cells
    Tonic Firing Rate
  21. _____ ____:
    • Depolarization of the ipsilateral hair cellsoccurs during angular head movements
    • Hyperpolarization of contralateral hair cellsoccurs at the same time
    • Hair cells are only able to hyperpolarize towhat they were at rest = cut off of inhibitoryinfluences from the movement going in theopposite direction even if the ipsilateral haircells continue to spike higher firing rates
  22. _____ _____ ____:
    • Perseveration of neural firing in the vestibularnerve by the brainstem after stimulation ofSSC to increase time constant (10sec.)– SSC respond by producing anexponentially decaying change in neuralfiring to sustained head movement
    • Otolith & somatosensory input also drivemechanism
    Velocity Storage Mechanism
  23. ____ ____ ____:
    • Causes eyes to move in the oppositedirection to head movement
    • Speed of the eye movement equals that ofthe head movement
    • Allows objects to remain in focus duringhead movements
    Vestibular Ocular Reflex
  24. ____ _____ ____:
    • Keeps eye still in space while head ismoving
    • Ratio of eye movement to head movement(equals 1)
    Vestibular Processing Gain
  25. ______: – Connection with vestibular cortex and reticularformation → arousal and conscious awarenessof body; discrimination between self movementvs. that of the environment
  26. _____ _____:
    – Junction of parietal and insular lobe
    – Target for afferents along with the cerebellum
    Vestibular Cortex
  27. _______:
    • Monitors vestibular performance
    • Readjusts central vestibular processingof static & dynamic postural activity
    • Modulates VOR
    • Provides inhibitory drive of VOR (allowsfor VORcancellation)
  28. _____ _____:
    • Provide motor output from the vestibularsystem to:
    – Extraocular muscles (part of VOR)
    – Spinal cord & skeletal muscles (generateantigravity postural activity to cervical,trunk & lower extremity muscles)
    Descending Pathways
  29. ______ ______: Generates compensatory body movementto maintain head and postural stability,thereby preventing falls
    Vestibulospinal Reflex
  30. _____ ______: Maintains head stability during active headon body movement
    Vestibulo-collic Reflex
  31. Progressive changes of vestibular system begin at age __.
  32. ______: primary diagnostic indicator in identifying vestibular lesions. Rapid alternating movements of eyes.
  33. _____ _____ ____: postural sway is measured during 6 different sensory conditions. Performance patterns may guide expectations for certain diagnoses.
    Sensory Organization Test
  34. Vestibular disorders are secondary only to ___ ___ pain.
    The NIH estimates ____% of the population over ___ years of age will experience a dizziness disorder during their life time.
    • low back pain
    • 40%
    • 40 years of age
  35. Progressive changes of vestibular system begin at age ___. Decreased number of hair cells. Decreased vestibular nerve fibers. Lead to dizziness and vertigo.
  36. _____ nystagmus: vestibular rotary, visual, etreme lateral gaze.
    _____ nystagmus: spontaneous, positional, gaze evoked.
    • Physiologic nystagmus
    • Pathologic Nystagmus
  37. ____ ____: direction of gaze will shift with the head movement. Cause degradation of the visual image. In severe cases, visual world will move with each movement.
    VOR dysfunction
  38. ____: asymmetrical firing of the two vestibular systems. Gives an illusion of spinning movement.
  39. ______: visual illusion of oscillating movement of stationary objects. Can arie with lesions of peripheral or central vestibular systems.
Card Set
Lecture 18
Lecture 18