Hearing and balance

Base of basilar membrane is tuned for which frequencies

high

apex is tuned for which frequencies

low frequencies

Difference between kinocilium and stereocilia

Stereocilia make up the hair bundle, kinocilium is one longer protrusion

What happens during depolarization of hair cells

K+ flows into the hair cell, opens Ca2+ channels, triggers release of neurotransmitters

Endolymph, inner hair cell and perilymph membrane potential

Which principle is used for high frequencies

Place principle

Which principle is used at low frequencies

phase locking

How do we localize sound at low frequencies

by the time difference (phase difference)

How do we localize sound at high frequencies

Via intensity

Major auditory pathway

Auditory nerve travels to

The signal is then relayed to

Finally it reaches

Auditory nerve travels to cochlear nucleus

The signal is then relayed to inferior colliculus

Finally it reaches primary auditory complex

What happens at the superior olivary complex

A neuron crosses the midline at the olivary complex and reaches the inferior colliculi

What does the superior olivary pathway help with

discriminating the direction of the speaker

Which structures are involved in this process [2]

Medial nucleus of the trapezoid nucleus (MNTB)

lateral superior olive (LSO)

Primary auditory cortex is also called

Broadmann’s area

Vestibular system is responsible for

balance

Angular acceleration occurs in

semicircular canals

Linear acceleration occurs in

vestibular sacs

Vestibular sacs are composed of

utricle and saccule

How do vestibular cells move

With gating-springs

Depolarization in stereocilia causes

K+ influx and Ca2+ entry into the cell

Sensory organs of semicircular canals

Ampullae which contains Cupula inside

What happens in response to rotation?

Endolymph flows in due to inertial forces

Results in depolarization, transmitter release, synaptic activation

Rotation to the right and left - effect on firing frequency

Left - decreased firing rate

Right - increased firing rate

What mediates the linear acceleration in utricle and saccule

Otoliths

The efferent nerve relays signals via (vestibulo-occular reflex)

medial vestibular nuclei

Where does it further connect to [5]

Efferent nerve projects via (thalamocortical pathway)

lateral and superior vestibular nuclei