Block 2 Exam: Auditory And Vestibular Systems Flashcards
The vestibular systems has ___ otolith organs. What are they and what do they detect?
Utricle and Saccule.
They detect changes in head angle/linear acceleration.
Each otolith organ in the vestibular system contains a _______. How is this orientated in each organ?
Macula
Vertically oriented in Saccule
Horizontally oriented in Utricle
What does the vestibular system used to detect head rotation?
3 semicircular canals at 90 degrees to each other.
Vestibular system:
______ & _____ are 30 degrees parallel to earth and perpendicular to gravity.
Semicircular canal/utricle
The macula of odolith organs contain ___ whose cilia project into gelantinous cap.
Hair Cells
The calcium carbonate crystals on top of the cap in vestibular system which weigh on cap and move due to gravity are called…
Otoliths
Hair cells are tonically active, which means
When head angle changes, amount of depolarization/hyperpolarization changes.
Vestibular: When cilia towards kinocilium
depolarize, excite afferents, Ca2+ and K+ flow
Vestibular: When cilia away from kinocilium
hyperpolarize, inhibit afferents, no Ca2+/K+ flow
Vestibular Semicircular canals:
The Ampulla has a sensory receptor called ____.
Crista
Vestibular system:
_______ of hair cells synapses on vestibular nerve.
Basal Membrane
What Nerve is the vestibular nerve?
Cranial Nerve 8
Vestibular nerve (#8) —> Lateral Vestibular Nucleus Pathway
Nerve 8 –> Lateral Vestibular Nucleus –> Cerebellum & Limb motor neurons
Vestibular nerve (#8) –> Medial Vestibular Nucleus Pathway
Nerve 8 –> Medial Vestibular Nucleus –> MEDIAL LONGITUDINAL FASISCULUS –> Extraocular motor areas (3,4,6) and neck motor neurons.
Where does most vestibular info go through in thalamus?
What lobe of the cortex gets most vestibular info?
Ventral posterior lateral nucleus of thalamus (VPL)
Parietal Lobe
What cortical areas receive direct vestibular projections straight from VPL?
Areas 3a, T3, and PIVC (parietoinsular vestibular cortex –> insular area)
What are these 3 other areas that get vestibular info and what do they do?
- VIP
- MST
- Frontal eye fields/superior colliculus
VIP: ventral intraparietal area–> Grasping things, where an item is in space
MST–> Medial superior temporal area–> some vestibular/vision info
Frontal eye fields/superior colliculus–> Eye localization
What are the functions of the vestibulocerebellum?
Position of head/body in space, equilibrium, eye orientation
COWS: Warm Water
*COWS is talking about horizontal nystagmus
Endolymph in ipsilateral horizontal canal rises, resulting in increased firing.
Eye toward contralateral (opposite ear from where water put in), with horizontal nystagmus (quick horizontal eye movement) to ipsilateral ear.
COWS: Cold Water
Endolymph falls, decrease rate of firing.
Eyes toward ipsilateral (same side) ear, horizontal nystagmus to contralateral ear.
What is pitch encoded as?
Frequency
low frequency = low sound
What is intensity (amplitude) of sound encoded as?
Loudness
Sound waves Pathway:
Pinna —> auditory canal –> move ________ —> ________, which move the membrane at oval window —> moves fluid in _____ –> Response in sensory neurons.
Pinna –> auditory canal –> move tympanic membrane (ear drum) –> ossicles, which allow larger pressure on cochlea –> membrane at oval window –> moves fluid in cochlea –> response in sensory neurons.
Sound waves move…
Ossicles move…
Oval Window moves…
Tympanic membrane
Membrane at oval window
fluid in cochlea
Ossicles amplify changes in pressure by altering ____ to help transduce waves into electrical energy.
force/surface area.
_____ moves in/out like a piston transmitting sound vibrations to inner ear at oval window.
Footplate of stapes
Pressure=
Force/Area
Ossciles increase fore and decrease surface area at oval window.
When you have a cold, ______ tube is clogged. Children’s is horizontal, so it gets infected because it is hard to drain.
Eustachian tube
What contains auditory receptor cells? (Hint: surrounded by tectorial membrane)
Organ of Corti
The fact that endolymph has an electrical potential 80 mV higher than perilymph is known as…
Endocochlear potential
What participates in active transport to maintain concentration gradients?
Stria Vascularis
Higher Frequency sounds processed by hair cells that are close to ____. Describe this.
Stapes
Base vibrates a lot, dissipates most energy and does not travel far.
Lower frequencies sounds travel down _______
Basilar membrane, travels down membrane.
The fact that the basilar membrane’s response establishes a place code in which different locations on the membrane are maximally deformed by different frequencies is known as….
Neural Coding of Pitch
Basalar membrane:
Base end vs. Apex end
Apex: Wide/floppy, low frequency, 500Hz, 1kHz
Base: Narrow/stiff, high frequency, 16kHz
What are the sensory receptor cells of auditory system?
Outer hair cells lie towards ____
Inner hair cells more towards _____
Hair cells.
Outer towards Apex
Inner towards modiulus
What do the rods of corti do in the organ of corti?
support hair cells.
A critical step in transduction of sound to neural signal involves _________ that bend hair cells.
Up/down oscillations
Hair cell apical surfaces has _____ stiffened cilia called stereocilia arranged in ascending height
50-100
___% of spiral ganglion neurons communicate with a small number of hair cells.
__% receive input for outer hair cells.
Inner hair cells innervate about ___ spiral ganglion cells.
95%
5%
10
Motor innervation causes stereocilia to move up/down in order to
amplify sounds and enhance tectorial membrane movements.
What part of the auditory pathway is responsible for processing interaural time differences and localizing sounds in space.
The superior olive
(and further as it projects to inferior colliculus).
The Lateral Lemiscus travels from…
Superior Olive –> Inferior Colliculus –> MGN
Integration of visual and auditory information is accomplished by…
Reciprocal projections from inferior colliculus back to the superior colliculus.
An involuntary muscle contraction that occurs in the middle ear in response to high-intensity sound stimuli or when the person starts to vocalize is processed by feedback (brain stem neurons send axons to outer hair cells). What is this called?
Attenuation reflex
Each cochlear nucleus receives input from one ear on the ___ side. All other auditory information is from both ears.
What is the only way that brain stem damage can produce damage in one ear?
Ipsilateral
If the cochlear nucleus or auditory nerve on one side is damaged.
Tonotophic Mapping: What is it?
Higher frequencies more ____.
Lower frequencies more _____.
Different frequencies at different points. This is continuous in auditory system (visible in brain).
Higher frequencies more rostral.
Lower frequencies more Caudal.
What frequencies use phase locking on every cycle or some fraction of cycles combined with tonotopic detection?
What frequencies rely on tonotopy alone?
Low frequencies (<3kHz)
High frequencies
Name the 3 properties of sound.
- Frequency (tonoophy and phase locking)
- Intensity (encoded by # axons/AP fired)
- Source- can be horizontal or vertical
Horizontal Source: Name the two types of processing and where they occur
Interaural time delay: medial superior olive
Interaural intensity difference- processed by lateral superior olive and medial nucleus of trapezoid body (MNTB).
Vertical Source
Reflections off pinna
Processing by cochlear nucleus and superior olivary nucleus.
