Auditory and Vestibular Systems

These flashcards cover key vocabulary and concepts related to the auditory and vestibular systems, as discussed in the lecture.

Cochlea

(auditory system) • snail

Endolymph

• Fluid in scala media, like intracellular fluid • K+ : high, 150mM • Na+ : low, 1 mM

Basilar membrane

A membrane in the cochlea that vibrates in response to sound, enabling sound frequency discrimination through tonotopy.

Organ of Corti

The sensory organ located on the basilar membrane that contains hair cells, which are essential for hearing.

Stereocilia

a bend inward/outward as basilar membrane moves downward/upward

Phase locking

APs fire at particular part of sound wave → timing of neurons firing

Interaural time delay

The difference in the time it takes for sound to reach each ear, used by the brain to locate the source of a sound.

Tinnitus

A condition characterized by hearing sounds that are not present, often described as ringing in the ears.

Tonotopy

which area of basilar membrane maximally deformed → which neurons fire → how quickly those neurons fire

Vestibular system

A sensory system located in the inner ear that contributes to the sense of balance and spatial orientation.

Perilymph

• Fluid in scala vestibuli and scala tympani, like CSF • K+ : low, 7mM • Na+ : high, 140 mM

Hair cells

• Have stereocilia that bend • Outer: amplify basilar membrane movement • Inner: transduction of movement to synaptic current (95% of synapses)

Conduction deafness

• Issue moving sound from outer ear to cochlea • Burst ear drum, impacted ear wax, ossicle disorders

Transduction

1. Stereocilia stretch 2. Mechanically-gated K+ channels open 3. K+ flows into cell —> Depolarization 4. Voltage-gated Ca2+ channels open —> More Depolarization 5. Glutamate released into synapse 6. Spiral ganglion fires AP

Nerve deafness

• Loss of hair cells or auditory nerves • Tumors, drugs, traumatically loud noises

Base

Narrow and stiff

High frequency

Apex

Wide and floppy

Low frequency

Labyrinth

(vestibular system) • maze

Low frequency

phase locking only

Intermediate frequency

both phase locking and tonotopy

High frequency

tonotopy only