[UCSB] PSY 106: Introduction to Biopsychology
A red center/green surround cell is completely saturated by red. How does it respond?
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Describe the structure of the retina (6.3)
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If an on-center ganglion cell has light hitting it in the surroundings, what response do you expect?
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True or False: the rods that are part of the center of a ganglions receptive field synapse on a horizontal cell first
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What type of objects only reflect light?
!ASK is mirror correct?
What is cataracts?
An opacity or discoloration of the lens = refraction goes insane = unclear image
Where is the retina located?
Beneath the choroid. It is the surface upon which light is focused; back of the eye
What is the sclera?
The tough supporting wall of the eye; also the white part of the eye
Where is the optic disc located?
Toward the nasal side of the retina
How much of the visual spectrum can we see?
VERY LIGHT
Where is the optic nerve?
Very back of the eye, stemming off
refractive problems
Visual disorders that occur when the refractive structures of the eye fail to properly focus light rays on the retina hyperopia(farsighted), myopia(nearsighted),
What is blindsight?
a condition in which a person can respond to a visual stimulus without consciously experiencing it
What is contrast enhancement?
a mechanism of our nervous system which highlights the difference between edges for us, like mach bands
What is scotoma?
a partial loss of vision or a blind spot in an otherwise normal visual field.
When a rod cell releases neurotransmitter.. does the bipolar cell release a neurotransmitter?
a rod cell releases GLUTAMATE when rhodopsin is not activated, cGMP is high, and cation channels are OPEN = INHIBITS bipolar cell so bipolar cell does not release a neurotransmitter same thing vice versa! ^
What is the Default Mode Network?
a set of brain regions that is more hemodynamically active during rest than during tasks communicates with language and speech areas = could be the internal monologue
(6.3) What cell types specialize in lateral communication?
amacrine cells and horiztonal cells
What is a receptive field?
area monitored by a single receptor cell
Where is the lens located?
behind the pupil and iris
Where is the iris located?
between cornea and lens
Where is the vitreous chamber located?
between lens and retina
Where is the choroid located?
between retina and sclera
Where is the ciliary body located?
between the choroid posteriorly and the iris anteriorly
What is the choroid?
black pigmented network of blood vessels used to nourish the eye
peripheral drift illusion
slight differences in the time it takes to process luminance/intensities of lights
How does the ciliary body attach to the lens?
suspensory ligaments
what is the brain's dark energy?
the 15% of remaining energy the brain uses that is NOT spent on processing external stimuli but is still being used
(6.1) Define sensitivity
the ability to detect the presence of dimly lit objects
(6.4) Define scotopic vision
the ability to perceive visual stimuli in near darkness due to the activity of rods = less detail, no color
(6.4) Define photopic vision
the ability to perceive visual stimuli under bright light conditions due to the activity of cones = fine detail
(6.1) Define acuity
the ability to see the details of objects
(6.3) what is the fovea?
the central focal point in the retina, around which the eye's cones cluster ( high acuity)
Explain the importance of binocular disparity (6.2)
the difference in the retinal images of the two eyes that provides information about depth; allows us to understand depth
what is accommodation?
the process by which the eye's lens changes shape to focus near or far objects on the retina
(6.3) Define surface interpolation
the process by which we perceive surfaces; the visual system extracts information about edges and from it infers the appearance of large surfaces
(6.1) Define accommodation
the process of adjusting the configuration of the lenses to bring images into focus on the retina
Explain how the pupil can affect the image that falls on the retina (6.1)
the pupil is a hole in iris that constricts to allow a certain amount of light in to balance sensitivity and acuity with the light in the environment very light = constrict, high acuity very dim = dilate, low acuity
What is the center of a ganglion cell's receptive field?
the rod that connects directly to a ganglion cell
Describe the duplexity theory of vision (6.4)
the theory that cones and rods mediate different kinds of vision cones = day rods = night
tunnel effect
trace outer lines with ur eyes and u end up not going towards the center because they are closed circles
What is rhodopsin?
visual pigment in rods
When is lateral inhibition highest?
when looking at objects that are HIGHLY ILLUMINATED
An object absorbs Red, Orange, Yellow, and purple waves and reflects the remaining. What color do we perceive this object to be?
Greenish Blue !ASK is this right?
(6.1) In very lit environments, what do the pupils do?
In a HIGH LIGHT environment, the pupil constricts (sensitivity is not important; acuity is used) = sharp image with large depth of field = HIGH APERTURE #
Explain how the lens can affect the image that falls on the retina (6.1)
It focuses incoming light onto the retina by adjusting the ciliary muscles distant object = flat lens close object = thick contracted lens
What is visual agnosia?
Lack of ability to recognize common objects and demonstrate their use in an activity.
How does the brain use only ~10 kbps?
- dark energy - default mode network
How does light travel through the eye?
- light travels through the cornea and through a lens, which focuses light on the focal point (fovea) - pupils dilate (dark) or constrict (light) - lens constricts (close) or flattens (far)
What is the resting membrane potential of rod cells?
-40 mV
What are three key differences between simple and complex cells?
1. Larger receptive fields 2. Respond to orientation of stimulus 3. Many are binocular instead of monocular *PIC: not from lectures!
How does visual transduction occur in the light?
1. Rhodopsin bleaches when exposed to light 2. drop in cGMP 3. cation channels (Ca 2+ and Na +) close 4. Dark current STOPS flowing 5. Ganglion cell voltage-gated Ca 2+ channel closes too 6. (NO GLUTAMATE RELEASE) bipolar cell releases neurotransmitter 7. neurotransmitter binds to ganglion receptor 8. ganglion cells sends info to the brain
Describe the overall layout of the retina
1. ganglion cells then 2. amacrine cells 3. bipolar cells 4. horizontal cells 5. Rods and cones 6. pigment epithelium LIGHT GOES THRU 1-5 onto 6 MANY rods combine into a few bipolar cells which converge into a ganglion cell which sends info to the optic nerve; All the axons gather into one place (optic nerve) = blind spot the rods are dispersed on the edge of the retina; cones are more centralized on the retina
What is glaucoma?
A condition characterized by increased intraocular pressure and progressive vision loss by damaging the optic nerve.
hyperopia
A condition in which visual images come to a focus behind the retina of the eye and vision is better for distant than for near objects -- called also farsightedness. underpowered eyes
(6.5) Define spectral sensitivity curve
A graph of the relative brightness of lights of the same intensity presented at different wavelengths
Bayesian Approach
A way of formalizing the idea that our perception is a combination of the current stimulus and our knowledge about the conditions of the world—what is and is not likely to occur. = making an image/model in our head from a few pieces of information
What is prosopagnosia?
Face blindness. Inability to identify an individual by their face. (including oneself)
How does visual transduction occur in the dark?
NORMALLY photoreceptor constantly sends information to ganglion cell BUT IN THE DARK.. (RODS) 1. current caused by sodium and calcium 2. photoreceptor cell depolarizes 3. graded potential transmits inside cell 4. voltage gated Ca channels open 5. GLUTAMATE released by photoreceptor 6. binds and HYPERPOLAIRZES 7. inhibits bipolar cell 8. no release to ganglion cell = no nerve signal
What are simple ganglion cells?
ON/OFF cells - have center and surrounded rods ON CELLS: 1. central spot = AP frequency increases 2. peripheral spot = AP frequency decreases 3. central illumination = AP frequency decreases 4. surround illumination = NO AP, but once the light turns off AP frequency increases = post-synaptic illumination effect 5. diffuse illumination = no change OFF = opposite! (except #5) https://gauchocast.hosted.panopto.com/Panopto/Pages/Viewer.aspx?id=a9e7c879-fc80-4ec0-8e94-abf000542584 16:40
What are mach bands?
Perception of a thin dark band on the dark side of a light-dark border and a thin light band on the light side of the border. These bands are an illusion because they occur even though corresponding intensity changes do not exist. *PIC: MACH BAND Is the SPIKE IN THE PERCIEVED INTENSITY
Explain how the difference between the photopic and scotopic spectral sensitivity curves amounts for the Perkinje effect (6.5)
Perkinje effect = at sunset yellow and red flowers brightest, but once sun set blue flowers were brightest sunset had more light = more cones being used = 560nm is brightest wavelength sun had set = less light = more rods = 500nm is brightest
What is the important aspect of a visual display?
THE EDGES
what is lateral inhibition?
The pattern of interaction among neurons in the visual system in which activity in one neuron inhibits adjacent neurons' responses.
What is the optic disc?
The site where the optic nerve attaches to the eye - no vision (photoreceptor cells) here. = blind spot
Explain the difference between the photopic and scotopic spectral sensitivity curves (6.5)
both = judging brightness of wavelengths of light photopic = shown on the FOVEA (cones), 560 nm scotopic = light shown on the periphery of the retina (rods), 500 nm
pupillary reflex
both pupils constrict when light is directed at one eye
Where is the pupil located?
center of iris
Where is the fovea?
center of retina
What is color deficiency?
color "blindness"; absence/reduction of a certain color cones (no red cones or a small # of red cones = problems seeing red) can be genetic or by disease
(6.3) Define lateral communication
communication across the major channels of sensory input
(6.1) when looking at something close up, what is the shape of your lens?
contracted, thick
What does the ciliary body do?
controls the shape of the lens
astigmatism
defective curvature of the cornea or lens of the eye = multiple of the same image on the retina
(6.1) In very dim environments, what do the pupils do?
dilate (low illumination to activate receptors) sacrificing acuity = lighter image so you can see something but not very sharp and a shallow field of depth (LOW APERATURE #)
What is the vitreous chamber?
filled with vitreous humor, jelly like substance, gives pressure to eye and shape to the eye
(6.1) when looking at something far away, what is the shape of your lens?
flat
Where is the cornea located?
front of eye
Explain why some vertebrates have one eye on each side of their head while other vertebrates have their eyes mounted side by side on the front of their heads (6.2)
having eyes on the front = able to see 3D objects from 2D objects and to better judge distance eyes on the sides = able to see behind them/wider FOV
How do cells respond to color?
if a specific color hits the center of the ganglion cell = AP freq increases Surrounding = AP freq decreases
What is achromatopsia?
inability to recognize colors; true color blindness; gray scale; rare
What are amacrine cells in the eye for?
inhibition; interneuron regulator between bipolar and ganglion cells.
What are horizontal cells in the eye for?
laterally interconnecting neurons that integrate and and regulate the input from multiple photoreceptor cells.
background distance effect
lines are the same length (background decieds)
How do you see edges? / How is our vision different from a camera/"reality"?
mach bands, contrast enhancement, and lateral inhibition
What is akinotopsia?
motion blindness
distance brightness effect
move further away and closer closer white = brighter farther = less bright
myopia
nearsightedness; lack of foresight; overpowered; refracting too much, the image is infront of the retina
Where is the sclera located?
outside of eyeball (white part of the eye)
Explain the differences between the photopic and scotopic systems (6.4)
photopic = cones, daytime, high acuity, FEW CONES to one ganglion cell scotopic = rods, nightime, no color or sharpness, LOTS OF RODS to one ganglion cell = less light needed to activate
What color is high energy light?
purple/blue
Name the cell types that make up the retina (6.3)
receptors, horizontal cells, bipolar cells, amacrine cells, and retinal ganglion cells. +each have subtypes (>60 total types! 30 ganglion)
What color is low energy light?
red
What is the difference between refraction and reflection and absorption?
refraction: The bending of a wave as it passes at an angle from one medium to another reflection: The bouncing back of a wave when it hits a surface through which it cannot pass. (COLOR; WHITE) absorption: Matter can capture electromagnetic radiation and convert the energy of a photon to internal energy (BLACK)
What are complex cells?
respond to orientation edge within anywhere of their RF
Which do we have more of: rods or cones?
rods
What is the surroundings of a ganglion cell's receptive field?
rods that connect to horizontal cells then to ganglion cells