NSCI 225 Learning Check 2

retinotopic mapping

Spatial organization in LGN and Cortex

- Flipped from what shows up in visual field

- Center magnified, Fovea does more processing, takes up more space

Column Organization

The organization PVC cells that respond to similar stimuli

- 6 layers stacked on top of each other, each layer processes the same info = location of individual field, orientation of lines, which eye is dominant

- Every single column respond to same location within retina, if orientation changes, neighboring receptive fields activated

- 6 cells down column give same recording

Hyper-Column

Location column, has every orientation of line, L and R dominance

- location columns emphasize location in visual field, hyper column highlights that the big columns have different types of cells

First place we have binocular cells

PVC/Cortex

- Information from either eye, still have preference from one eye

Where is your receptive field

ALWAYS on retina

Grating adaptation

- Simple cell firing, neurons adapt after extended exposure, neurons fire less when stimulus repeated

- Grating adaptation ONLY occurs if adapting grating has same orientation as test grating

→ adapting cells are orientation specific

- Happens first in the CORTEX

- Interocular transfer: adapting with 1 eye but effect still present in other (binocular cells)

Extrastriate areas

V1, V2, V3, V4, V5

- code for increasingly complex components of vision, objects get more complex, shape forms, then object uniqueness, size of receptive field gets larger

- as we move further down the pathway, we have more specific types of receptive fields (IT Cortex neurons)

"Where" pathway

parietal cortex, dorsal stream

- Patient RV had damage (could not do action, bad at grasping rocks, can copy images/recognize)

--> Bilateral parietal damage, damage/ optic ataxia, SUBconscious, How pathway also

"What" Pathway

temporal cortex, ventral stream

- Agnosia

- Patient DF had damage to WHAT pathway, could put card in slot, but couldn't match orientation, couldn't ID family until they spoke, unable to describe orientation, conscious

- Earlier damage to V1 compared to Mr. P

FFA/PPA and Greebles

FFA: faces

PPA: places

Greebles: FFA goes beyond faces, shows visual expertise, picks up detail and more complex images

Dr. P

Visual Agnosia, knows where but not WHAT

Early, Middle, High level vision

Early: grouping, combining features, Gestalt (Modal completion)

Middle: constructing surfaces/objects from contours, Segmentation (figure/ground), 3D, Amodal completion, binocularity

High: Unique features, classes of objects identified by shape, complex shapes as combinations of simple shapes, light from above

law of good continuation

elements that appear to follow the same pathway tend to be grouped together

- continue pattern established an implied direction

law of simplicity (pragnanz)

the most general, which states that the simplest organization, requiring the least cognitive effort, past experience

Law of similarity

grouping objects based on similar properties, color, shape, texture

Law of Proximity

objects positioned close often seen as not separate parts but one whole

Law of common fate

MOVEMENT, tend to group similar objects together that share a common motion or destination,

Law of familarity

things are more likely to form groups if the groups appear familiar or meaningful

principle of common region

Objects sharing a common background will be perceived as a group even if they would be separated by eh principles of nearness and/or similarity, within same region of space grouped together

principle of synchrony

visual events that occur at the same time are perceived as belonging together, TIMING

figure vs. ground

- Position in visual field, tend to perceive lower as figure

- Convexity: things more convex/sticking out as figure

- Symmetry, Size and orientation (vertical or horizontal more likely figure), familiarity,

amodal completion

- MID level, Surfaces completing behind an occluding surface, Surface is not seen but is "registered", unconscious, depth cue = occlusion

semantic regularities

characteristics associated with the functions carried out in different types of scenes

- Using schemas

monocular depth cues

One eye

- Occlusion, Relative Height, Relative size, Familiar size (knowing size of one obj in real life allows you to make comparison), Shadow/shading (where light is coming from), Atmosphere perspective (due to atmosphere, obj look less sharp and clear further away), Linear perspective (convergence creates depth), Texture Gradient (less texture is further back)

- Movement produced cues: motion parallax (obj closer pass by faster than those further), deletion and accretion (gradual occlusion)

Ocular depth cues

Ponzo illusion

An illusion of size in which two objects of equal size that are positioned between two converging lines appear to be different in size. Also called the railroad track illusion.

- Further away but casting same retinal image = must be bigger, perspective convergence

moon illusion

An illusion in which the moon appears to be larger when it is on or near the horizon than when it is high in the sky.

- as moon is up in the sky it looks closer, closer to horizon looks further

- Same size retinal image, further away = Larger

- More depth cues at horizontal when compared to blackness, relative height with horizon = further away

Extraocular cues

Convergence: binocular, muscles direct eyes to look in different directions

Accommodation and Blur: monocular: intraocular muscles adjusting the shape of lens

corresponding points

a point on the left retina and a point on the right retina that would coincide if the two retinas were superimposed - for example, the foveas of the two eyes, NOT MIRROR IMAGE,

Horoptor

Anything on horopter will correspond with same points, temporal left side will be on right nasal size

- More disparity = obj FARTHER from horopter

- Closer= crossed disparity

- Further: uncrossed disparity

Stereopsis

Charles Wheatsone, the process by which the visual cortex combines the differing neural signals caused by binocular disparity, resulting in the perception of depth

- binocular disparity is important for depth perception = STEREOPSIS, for this perception of depth, and invented the stereoscope.

Perceptual outcome of disparity = geometrical

- Neurons in fovea have close to 0 disparity (cortical magnification)

Where is disparity first seem

Where/how pathway

- Cells in PVC that follow this pathway, without disparity selective neurons we would not develop binocular neurons,

Reflectance curves

a plot showing the percentage of light reflected from an object versus wavelength

- NEVER perfect curve/peak

- White= all pigments reflected pretty equally

Primary colors

Primary colors for paint mixing: Magenta, Cyan, Yellow (subtractive, make black)

Primary colors for light mixing: RED, GREEN, BLUE (additive)

trichromatic theory of color vision

The theory that there are three kinds of cones in the retina, each of which responds primarily to a specific range of wavelengths

- Metameters: test color and color fields

rod vs come monochromat

Rod monochromat: bad acuity, shades of gray, 0 functioning

Cone monochromat: good acuity, can be seen in fovea, no color (scales of gray), Only 1 functioning cone

Dichromats

People who can distinguish only two of the three basic colors.

- Ishihara plates used to diagnose

Tetrachromats

women who have 4 types of cones, which likely allows them to see

about 100 million colors

- can distinguish more fine shades in ranges of color than normal person

opponent-process theory

the theory that opposing retinal processes (red-green, yellow-blue, white-black) enable color vision. For example, some cells are stimulated by green and inhibited by red; others are stimulated by red and inhibited by green

- Excitatory of one color, inhibitory of opposite color (Excitatory from blue, inhibition from red and green)

- BOTH opponent process theory (hue cancellation = LGN) and trichromatic theory (color matching = RETINA) are right,

What effects color constancy

Seeing colors as same over varying illuminations/light sources

- chromatic adaptation

- surrounding effect

- memory and color

- Brightness consistency, illuminance edge vs reflectance

- Dress: effect of surrounding

illuminance edge

created by SHADOW

reflectance edge

created by ACTUAL brightness/color difference

Which cell would have the biggest receptive field?

A. V4 cell

B. Retinal cell

C. V1 cell

D. Simple cell

A

Which approximate wavelengths correspond with the proper color that would be perceived?

A. Blue = short wavelengths

B. Green = medium wavelengths

C. Red = Long wavelengths

D. All of the above are correct.

D

How is a visual receptive field defined?

A. The region on the ganglion receptors that, when stimulated, increase a cells firing rate

B. The area of the visual cortex that becomes active when a stimulus is detected

C. The region on the cornea that certain receptors are stimulated by

D. The area on the retina that, when stimulated, causes some change to the cells firing rate

D

Which of the following statements is TRUE regarding columns in V1?

A. Every cell in the same hypercolumn has approximately the same receptive field location.

B. Every cell in the same orientation column has approximately the same receptive field location.

C. Neighboring hypercolumns have neighboring receptive field locations on the retina

D. all of the above

D

Suppose you were to review dozens of photographs of various natural and manmade scenes on social media. You would expect that _____

A. horizontal and vertical orientations would be most common

B. oblique orientations would be most common

C. the major environmental regularities would be incompatible with Gestalt principals

A

Due to the cortical magnification effect, which of the following objects would you expect to occupy the greatest processing area on the cortex?

A. A skyscraper falling on the optic nerve

B. A mouse within the focus of vision

C. An cat in your peripheral vision

B

What takes up largest part of V1 compared to its size

Fovea

Dorsal pathway leads to

parietal lobe

Where does grating adaptation occur?

Cortex

Patient RV would likely be diagnosed with

Optic Atxia

Which pathway is associated with Agnosia

WHAT pathway

Stage of object perception that is about feature detecting and combining them

Early vision

Making 3D with 2D retinal image

Inverse Projection Problem

Type of completion that allows you to complete a partially hidden object to make sense of a scene

Amodal Completion

Depth cue involved in Ponzo Illusion

Linear Perspective, Perspective convergence

Name of invisible semi-circle, anything landing on it will be projected to corresponding points on retina

Horopter

Crossed disparity

a type of binocular disparity produced by an object that is closer than the horopter - you would have to "cross" your eyes to look at it

- closer to you than what you are foveating on

Perceptual experience produced by binocular disparity

stereopsis

2 types of cones that are missing/not functioning

monochromat

Penumbra

The part of a shadow surrounding the darkest part, fuzzy edge of shadow

You are a researcher recording from a cortical neuron. You shined a horizontal bar of light on the screen but see no significant change from baseline activity. Which of the following would be the LEAST likely to change the activity of the cell?

A. Move the bar of light back and forth in some direction

B. move the bar of light to a different location on the screen.

C. Change the orientation of the bar of light.

D. Increase the intensity of the stimulus

D

Corey looks at a flock of seagulls flying in one direction, when suddenly, five of the seagulls start flying in another direction. He now perceives two groups of birds, because of the Gestalt principle of _____.

Common fate

Which of the following is true about D.F.?

A. She had damage to the dorsal pathway

B. She had optic ataxia

C. She could not pick up objects correctly

D. She could draw images from memory

E. More than one above

D

Which of the following is true about selective adaptation?

A. it is a short term effect

B. the firing rate of neurons decreases

C. neurons adapt to a repeated stimulus

D. all of the above

D

Where do we first see the disparity-selective neurons?

V1, Where pathway

Perception of light is

related to PERCENTAGE of light reflected, not amount, ratio principle: two areas that reflect different amounts of light look same if ratio of intensities are same

Which of the below images depicts corresponding points on the two retinas?

A. both same orientation and side

B. opposite orientation and opposite side (mirror)

C. different orientations and random locations

D. Both A & B

A

Compared to that of a neuron earlier in the visual pathway, the ideal stimulus for a neuron further in visual pathway will be

A. more complex and confined to a smaller area of the visual field

B. more simple and confined to a smaller area of the visual field

C. more simple and occurring anywhere within a large portion of the visual field

D. more complex and occurring anywhere within a large portion of the visual field

D

If something is located beyond what you are focusing on at the time, it will have _________ on the retinas.

A. no disparity

B. crossed disparity

C. uncrossed disparity

C

What is the name for someone who is missing one type of cone?

A. Monochromat

B. Ishihara

C. Trichromat

D. Dichromat

D

A pair of 3D glasses provide the illusion of depth in a 2-D images by _____.

A. rapidly alternating between two images

B. presenting an image to each eye that have slightly different sized items in them

C. presenting an image to each eye at different distances from the retina

D. presenting an image to each eye that are from slightly different perspectives

D

What is one likely reason people see "the dress" differently?

A. Our minds are automatically removing different wavelengths of ambient lighting from the image.

B. We have different numbers of each type of opponent neuron.

C. We have different color preferences that bias us toward one color or another.

D. Our 3 cone types are firing in different ratios.

A

Which is the best explanation of the moon illusion? Hint: Think about the Ponzo Illusion!

A. As the moon becomes closer to the horizon, it looks like it is closer, so it appears to be bigger.

B. As the moon becomes closer to the horizon, it looks like it is further away, so it appears to be smaller.

C. As the moon becomes closer to the horizon, it looks like it is closer, so it appears to be smaller.

D. As the moon becomes closer to the horizon, it looks like it is further away, so it appears to be bigger.

D

If you close your left eye and adapt your right eye to a grating of vertical lines, which of the below statements would be TRUE, and why?

A. You would NOT show the adaptation effect for horizontal lines; because the effect is happening in the cortical cells.

B. Your left eye would NOT show the adaptation effect; because the effect is happening in the cortical cells.

C. Your left eye WOULD still show the adaptation effect; because adaption is happening in LGN cells.

D. You WOULD also show the adaptation effect for horizontal lines; because adaptation is happening in the LGN cells.

A