Brain Bee - Chapter 2 - Senses & Perception

Name the process of turning stimuli into electrical signals

transduction

Name the most complicated sense.

vision

What percent of the cerebral cortex involves vision?

30%

What animal was studied to understand how vision works?

Drosophila

Name two animals that were studied to understand higher level visual processing.

monkeys and cats

What structure in the eye does light first pass through?

cornea

Name the structure that light passes through after the cornea.

pupil

Name the structure that regulates the amount of light entering the eye.

iris

What can the iris change?

size of pupil

Name the structure that bends the light.

lens

What structure does the light focus on inside your eye?

retina

What structure in the eye does the initial focusing?

cornea

What structure can thicken or flatten to bring near or far objects into better focus?

lens

How is visual input mapped onto the retina?

two dimensional and reversed

Where do objects on a persons right project to inside the eye?

left side of retina

Where do objects that are above project to inside the eye?

lower part of retina

How many layers is the retina?

3 layer

How do signals travel from the eye to parts of your brain?

optic nerve

What will you brain do with the information it receives from your eyes?

integration and interpretation

Name the three type of neurons found in the retina.

photoreceptors, interneurons and ganglion

Name two types of photoreceptors.

rods and cones

Where would you find rods and cones?

most peripheral layer of the retina

What structures does light travel through before getting to the photoreceptors?

cornea, lense, ganglion and interneurons

Ganglion and interneuron cells respond directly to light.

False

(T/F) Ganglion interneuron cells do not respond directly to light.

True

What is the function of ganglion and interneuron cells in the retina?

process and relay information from the photoreceptors

What structures make up the optic nerve?

axons of ganglion cells

How many photoreceptors are in each human eye?

125 million

What is the function of photoreceptors?

turn light into electrical signals

What percent of photoreceptors are rods?

95%

What is the function of rods?

allow you to see in dim light

What is the function of cones?

pick up fine detail and color

How many type of cone cells in the eye are there?

three

Name the three type of cone cells.

red, green and blue

How are your eyes like a computer?

mix red, green and blue levels to generate millions of colors

Where in the retina would you find more cones?

center

Name the very center of the retina.

fovea

What cone cells are found in the fovea?

red and green

What can the fovea do that other parts of the retina cannot?

resolve fine detail

Name the area that surrounds the fovea.

macula

The macula is critical for what every day activities?

reading and driving

Name the leading cause of blindness in people older than 55.

macular degeneration

What is macular degeneration?

degeneration or death of photoreceptors

What region of the eye has the highest visual acuity?

macular region

How many photoreceptor cells interact with one ganglion cell found in the macular region of the eye?

one or very few cones

How many photoreceptor cells interact with one ganglion cell found in the margins of the retina?

several photoreceptor cells

What is the portion of visual space providing input to a single ganglion cell called?

receptive field

What cells provide nutrition for the retina?

astrocytes

What does visual processing begin with?

comparing the amounts of light hitting small adjacent areas of the retina

How does the ganglion cell respond when light hits the entire receptive field (the donut and its hole)?

weakly

How does the ganglion cell respond when light hits the center of the receptive field?

activated

How does the ganglion cell respond when light hits the donut shaped area surrounding the receptive field?

inhibited

Where do the optic nerves travel towards?

back of the brain

What is located at the exit point of the optic nerve from the eye?

blind spot

What is missing where the optic nerve exits the eye?

photoreceptors

Name the junction where the two optic nerves cross.

optic chiasm

Where does the information from the left side of the retinas of both eyes go?

left side of the brain

Where does the information from the right side of the retinas of both eyes go?

right side of the brain

Where does visual information go after the optic chiasm?

lateral geniculate nucleus

What structure contains the lateral geniculate nucleus?

thalamus

Where is the visual information relayed to after the thalamus?

primary visual cortex

Where is the primary visual cortex located?

rear of the brain

How big is the primary visual cortex?

no larger than a half dollar

Which lobe contains the primary visual cortex?

occipital lobe

Which layer of the primary visual cortex receives messages from the thalamus?

middle layer

What does the primary visual cortex and retina have in common?

receptive fields

What can cells above and below the middle layer of the primary visual cortex perceive?

stimuli shaped like bars or edges and orientations

What animal was studied in order to understand how visual signals are processed?

monkeys

What did the studies in monkeys suggest about processing visual information?

several parallel processing streams

Name the lobe where the two visual dorsal streams go?

parietal lobe

What lobe does the ventral vision stream go to?

temporal lobe

What was originally believed about the visual streams?

processing of unconscious vision

Which stream(s) is associated with the "what"?

ventral stream

Which stream(s) is associated the "where"?

dorsal stream

What does the ventral stream allow your brain to do?

shape and color with memories and experiences

What does the dorsal stream allow your brain to do?

combine various spatial relationships, motion and timing to create an action plan

T/F The dorsal stream allows you to respond without the need for conscious thought.

True

T/F The dorsal stream does not allows you to respond without the need for conscious thought.

False

What does new research suggest about the division of labor of the visual streams?

there is crosstalk between streams

T/F Crosstalk may actually create a conscious experience.

True

T/F Crosstalk does create a conscious experience.

True

What do you call seeing with two eyes?

binocular vision

What does having binocular vision allow you to do?

perceive depth or three dimensions

For you to see in three dimensions what must your eyes do?

visual fields must overlap

Crossed eyes is called what?

strabismus

People with strabismus have difficulty with what?

depth perception

What animals were studied that led us to find better therapies for strabismus?

cats and monkeys

What do children with strabismus have difficulty with?

fuse the images coming from both eyes

What can happen if children with strabismus start to favor one eye?

lose vision in the other

T/F Vision cannot be restored after loss of vision in children with strabismus.

False

T/F Vision can be restored after loss of vision in children with strabismus.

True

At what age will the loss of vision due to strabismus be permanent?

8

Up until a few decades ago, what age did opthalmologists wait to surgically align the eyes of children with strabismus?

4

What age is strabismus corrected these days?

before the age of 4

What causes various disorders of blindness?

loss of function or death of photorecptors

What type of treatments are researchers currently working on for genetic blindness?

gene or stem cell therapies

What form of blindness has gene therapies been successful in treating?

macular degeneration

Instead of restoring lost photoreceptors, what are researchers currently trying?

sending electrical signals via ganglion cells directly to the brain

Sending electrical signals via ganglion cells directly to the brain to treat blindness is similar to what other treatment?

cochlear implants to treat deafness

Name 4 qualities hearing can distinguish?

pitch, loudness, duration and location