Lecture 3

Flashcards about Neural Pathways of Vision and Hearing

Depolarized

In the absence of light, the photoreceptor is in this state.

Hyperpolarizes

When light strikes the photoreceptor cell, the cell does this.

Depolarize

In the ON pathway, decreased glutamate release from the photoreceptor cell causes the bipolar cell to do this.

Hyperpolarize

In the OFF pathway, decreased glutamate release from the photoreceptor cell causes the bipolar cell to do this.

Photoreceptor and bipolar cells

These cells undergo graded responses and lack voltage-gated sodium channels.

Ganglion cells

These cells have voltage-gated sodium channels and are the first in the pathway where action potentials can be initiated.

Depolarized

In the absence of light, the photoreceptors are in this state, causing the release of glutamate.

Decrease

Light striking the photoreceptors causes this change in glutamate release.

Depolarize

Bipolar cells of the ON pathway do this spontaneously in the absence of input.

Hyperpolarize

Bipolar cells of the OFF pathway do this in the absence of input.

Inhibitory

Glutamate receptors of ON pathway bipolar cells have this effect.

Excitatory

Glutamate receptors of OFF pathway bipolar cells have this effect.

Depolarized

In the absence of light, cGMP binds to cation channels causing the photoreceptor cell to be…

Reduced glutamate release

In the presence of light, cGMP is broken down, leading to…

Ionotropic

glutamate receptors of OFF pathway bipolar cells

Image resolutions improved by

The coexistence of the ON and OFF pathways

Occipital lobe

The location of the visual cortex.

Where does the nasal region hit?

In the left eye, information from the lateral half of the field of view hits the nasal region of the retina

Contralateral (opposite)

Information from the nasal retina crosses to this side of the cortex at the optic chiasm.

Contralateral

Visual information from each eye goes both to the same side of the brain and also this side of the brain.

Temporal lobe

The lobe which contains the auditory cortex

Zones of compression

are regions where air molecules are tightly packed together

Zones of rarefaction

are regions where there are relatively few air molecules

Amplitude (volume or loudness)

This is determined by how many air molecules are located within a zone of compression.

Frequency determines…

Pitch

Tympanic membrane (eardrum)

This structure vibrates in and out as air molecules push against it.

Malleus, incus, and stapes

The three bones located in the middle ear are…

Inner ear

This part of the ear is filled with fluid.

Tensor tympani and stapedius

These muscles contract to dampen movement of the bones in response to loud sounds.

Oval window of the cochlea

The stapes terminates on this part of the inner ear.

The three compartments of the cochlea are…

Scala vestibuli, scala tympani, and cochlear duct

Endolymph

The cochlear duct contains this fluid.

Cochlear duct

The sensory receptors for the auditory system are located here.

The sensory receptors for the auditory system

Hair cells

where are hair cells located

Organ of Corti

The Organ of Corti allows for…

Transduction of sound vibrations into neural signals

Stereocilia of the inner hair cells

extend into the endolymph and transduce pressure waves into receptor potentials.

Basilar membrane

Different regions of this vibrate maximally at different frequencies.

Vestibulocochlear nerve

This nerve takes auditory information from the ear towards the brain.

when sterocila move what channels open?

Mechanically-gated potassium channel

Potassium

When stereocilia bend towards the tallest member, this ion flows into the cell.

Glutamate

The neurotransmitter released onto afferent neurons in the ear.

Brainstem

Cochlear nerve fibers synapse with interneurons here.

Thalamus

Sound information is transmitted here after the brainstem.

Temporal lobe

Location of the auditory cortex.

Hearing aids

These hearing devices amplify existing sounds.

Cochlear implant

This hearing device bypasses the outer, middle, and inner ear to directly stimulate the vestibulocochlear nerve.