Lecture 11: Ear and Neural circuits

Tympanic cavity is separated from external ear by __________ __________.

tympanic membrane.

Tympanic cavity is separated from inner ear by __________ and __________ __________.

oval;
round windows.

Tympanic cavity has 3 bones (auditory ossicles):

malleus;
incus;
stapes.

Auditory ossicles are responsible for transmitting sound vibrations from tympanic membrane to __________ __________.

oval window (and fluid of inner ear).

Auditory ossicles amplify sound waves so they can travel through __________ medium of inner ear.

fluid.

Two muscles (__________ __________ and __________) contract to diminish the strength of incoming waves and protect the inner ear from loud sounds.

tensor tympani;
stapedius.

Auditory tube is AKA __________ __________.

Eustachian tube.

Eustachian tube opens to the __________.

nasopharynx.

Eustachian tube equalizes pressure within the tympanic cavity with __________ __________.

atmospheric pressure.

The __________ is a snail-shaped, spiral chamber.

cochlea.

Cochlea houses the __________ organ, the organ of hearing.

spiral.

Bony labyrinth is partitioned into three chambers by __________ membranes.

two.

Three chambers of the bony labyrinth:

Scala vesitbuli
Scala media
Scala tympani

Scala __________ is the superior chamber.

vestibuli.

The floor of the scala vestibuli is the __________ __________.

vestibular membrane.

Proximal end of the Scala vesitbuli houses the __________ __________, which connects to the middle ear.

oval window.

Scala __________ is AKA cochlear duct.

media.

Scala __________ is the membranous labyrinth.

media.

Scala __________ is the middle chamber of the bony labyrinth.

middle.

Scala media houses the __________ __________.

spiral organ.

Roof of the Scala media is the __________ __________.

vestibular membrane.

Floor of the Scala media is the __________ __________.

basilar membrane.

Scala __________is the inferior chamber of bony labyrinth.

tympani.

Roof of the Scala tympani is the __________ __________.

basilar membrane.

Distal end of the Scala tympani houses __________ __________, which is sealed from the middle ear.

round window.

__________ is the point where the Scala vestibuli becomes the Scala tympani.

helicotrema.

Helicotrema is located at the __________ of the cochlea.

apex.

Organ of __________ is the organ of hearing.

Corti.

Organ of Corti is located within the Scala __________.

media (cochlear duct).

__________ membrane of the Organ of Corti is the stiff, gelatinous membrane.

tectorial.

Tectorial membrane overlies and contacts __________ __________ cells.

outer hair cells.

Hair cells in the Organ of Corti are arranged over the __________ __________.

basilar membrane.

There is __________ row(s) of inner hair cells.

one.

One row of inner hair cells is free floating in __________.

endolymph.

The one row of inner hair cells acts as the __________ __________.

sensory receptor.

There is __________ row(s) of outer hair cells.

three.

Three rows of outer hair cells project into __________ __________.

tectorial membrane.

Three rows of outer hair cells modulate activity within the __________ __________ __________.

Organ of Corti.

Spiral ganglion in the Organ of Corti possess __________ fibers from hair cells.

afferent.

Spiral ganglion in Organ of Corti join to form cochlear branch of __________ __________.

CN VIII (Vestibulocochlear nerve).

Hearing is the neural perception of __________ __________.

sound energy.

Sound waves are traveling vibrations of a __________.

molecule.

Sound waves alternate high & low pressure caused by the __________ and __________ of air molecules.

compression, rarefaction (de-compression).

Sound energy __________ as it travels from the source.

dissipates.

Sound is characterized by __________ and __________.

frequency; intensity.

Frequency describes the __________ of waves that pass a given point in a period of time.

number.

Frequency is measured in __________.

Hertz.

Frequency is interpreted as __________.

pitch.

Intensity of sound is represented by the __________ of the wave.

amplitude.

Intensity is measured in __________.

decibels (dB).

Sound waves are collected by the __________ and directed to the tympanic membrane.

auricle.

Tympanic membrane vibrates in response to the __________ __________ and transfers energy to the auditory ossicles.

pressure wave.

Tympanic membrane vibrates in response to the pressure wave and transfers energy to the __________ __________.

auditory ossicles.

The tympanic membrane vibrates at the same __________ as the incoming sound waves.

frequency.

Auditory ossicles amplify the vibrations and transfer the energy to the __________ __________.

oval window.

Oval window vibrates at the same __________ as the incoming soundwave.

frequency.

Oval window transfers the energy to the __________ of the Scala vestibuli, creating a pressure wave.

perilymph.

When stapes moves outward, then __________ pressure.

negative.

When stapes moves inward, then __________ pressure.

positive.

Pressure wave in Scale vestibuli displaces the __________ __________ at a specific location for that particular frequency.

vestibular membrane.

Displacement of the vestibular membrane causes a pressure wave within the perilymph in the cochlear duct, which displaces the __________ __________.

basilar membrane.

Upward movement of the basilar membrane displaces __________ away from the hinge of the tectorial memmbrane.

endolymph.

__________ hair cells move with the tectorial membrane.

outer.

__________ hair cells move with the endolymph.

inner.

Outer hair cells contract in response to __________.

depolarization

Outer hair cells contract in response to __________ protein in membrane.

Prestin.

Prestin protein movement accentuates (emphasizes) __________ __________ displacement.

basilar membrane.

Hearing signal is sent along __________ fibers.

auditory.

Downward movement of the __________ __________ displaces endolymph towards the hinge of the tectorial membrane.

basilar membrane.

Outer hair cells move with the tectorial membrane and __________.

hyperpolarize.

Hyperpolarization of outer hair cells __________ movement.

accentuates (emphasizes).

Closing of channels __________ nerve signals sent to the CNS.

nerve signals.

Pressure wave caused by displacement of the basilar membrane progresses to __________ __________.

round window.

Round window bulges and absorbs remaining __________.

energy.

__________ __________ is the ability to distinguish between various frequencies of incoming sound waves.

frequency discrimination.

Frequency discrimination is the result of __________ __________.

place coding.

Place coding describes when sound waves travel to the region within the __________ __________ that responds maximally to that frequency.

spiral organ (Organ of Corti).

Basilar membrane is structured so that high frequency sounds stimulate the __________ __________, while low frequency ends stimulate the __________ __________.

basal end;
apical end.

__________ __________ is dependent on the amplitude of the vibrations.

amplitude discrimination.

Amplitude discrimination is the result of __________ __________.

rate coding.

When exposed to higher amplitude, the __________ __________ vibrates more vigorously.

basilar membrane.

__________ are synaptically interconnected network of neurons.

circuits.

Each neuron within a circuit has __________ properties.

specialized.

Local circuits are the neurons (and their synapses) located in a local region of the __________.

brain.

Local circuits contain sets of __________, __________ and interconnected neurons essential for the function of that region.

inputs;
outputs.

Microcircuits are __________ arrangements of neurons.

finer.

The input of a local circuit in the spinal cord are from __________ __________ neurons, __________ axons, and __________ __________ input.

afferent sensory neurons;
descending axons;
spinal cord input.

Spinal cord input are __________ and nearby segments.

contralateral.

Processing of a local circuit in the spinal cord occurs in __________ (excitatory and inhibitory), and receive input directly or through other __________.

interneurons (excitatory or inhibitory).

Output of local circuit in the spinal cord is __________ neurons.

motor.

Input of a local circuit in the cerebral cortex is __________ axons, __________ neurons, and neurons from __________ local circuits.

ascending axons;
relay neurons;
neurons from adjacent local circuits.

Processing of a local circuit in the cerebral cortex is in __________ (excitatory and inhibitory), and receive input directly or through other __________.

interneurons.

Output of a local circuit in the cerebral cortex is from __________ fibers.

projection.

__________ __________ is responsible for the integration of many basic reflexes.

spinal cord.

__________ is a rapid, pre-programmed, involuntary reaction of muscles or glands to a stimulus.

reflex.

__________ is a sensory input that initiates relfex.

simulus.

Reflexes are a __________ response, so it requires few neurons involved.

rapid.

Reflexes are a __________-__________ response, meaning it has the same response every time.

pre-programmed.

Reflexes are __________, so the response requires no conscious intent, and can’t be suppressed.

involuntary.

Two kinds of reflexes:

basic, conditioned.