Chapter 4: Visual System: The Brain

Question 1

Optic chiasm

Answer 1

the location in the optic tract where the optic nerve from each eye splits in half, with nasal retinae crossing over and temporal retinae staying on the same side of the optic tract

Question 2

Optic tract

Answer 2

the optic nerve starting at the optic chiasm and continuing into the brain

Question 3

Contralateral representation of visual space:

Answer 3

the arrangement whereby the left visual world goes to the right side of the brain, and the right visual world goes to the left side of the brain

Question 4

Ipsilateral organization

Answer 4

same-side organization; in the visual system, the temporal retina projects to the same side of the brain

Question 5

Contralateral organization

Answer 5

opposite-side organization; in the visual system, the nasal retina projects to the opposite side of the brain

Question 6

Lateral geniculate nucleus (LGN)

Answer 6

a bilateral structure (one is present in each hemisphere) in the thalamus that relays information from the optic nerve to the visual cortex

Question 7

Magnocellular layers

Answer 7

layers of the lateral geniculate nucleus with large cells that receive input from M ganglion cells (parasol retinal ganglion cells)

Question 8

Parvocellular layers

Answer 8

layers of the lateral geniculate nucleus with small cells that receive input from P ganglion cells (midget retinal ganglion cells)

Question 9

Koniocellular layers

Answer 9

layers of the lateral geniculate nucleus with very small cells that receive input from K ganglion cells (bistratified retinal ganglion cells)

Question 10

Parasol retinal ganglion cells
(M cells)

Answer 10

retinal ganglion cells that project to the magnocellular layer of the lateral geniculate nucleus; they represent 10% of ganglion cells and possess high sensitivity to light

Question 11

Midget retinal ganglion cells
(P cells)

Answer 11

retinal ganglion cells that project to the parvocellular layer of the lateral geniculate nucleus; they represent 80% of ganglion cells, possess low sensitivity to light, and are sensitive to wavelength

Question 12

Bistratified retinal ganglion cells (K cells)

Answer 12

retinal ganglion cells that project to the koniocellular layer of the lateral geniculate nucleus; they represent 10% of ganglion cells, possess low sensitivity to light, and are sensitive to wavelength

Question 13

Parvocellular pathway
(P pathway)

Answer 13

a pathway characterized by the retinal ganglion cells known as midget retinal ganglion cells

Question 14

Koniocellular pathway (K pathway)

Answer 14

a pathway that starts with bistratified retinal ganglion cells and projects to the koniocellular layers of the lateral geniculate nucleus

Question 15

Magnocellular pathway
(M pathway)

Answer 15

a pathway that starts with the parasol retinal ganglion cells and projects to the magnocellular layers of the lateral geniculate nucleus

Question 16

Superior colliculus

Answer 16

a structure located at the top of the brain stem, just beneath the thalamus, whose main function in mammals (including humans) is the control of eye movements

Question 17

Smooth-pursuit eye movements

Answer 17

voluntary tracking eye movements

Question 18

Saccades

Answer 18

the most common and rapid of eye movements; sudden eye movements that are used to look from one object to another

Question 19

Primary visual cortex (V1)

Answer 19

the area of the cerebral cortex that receives input from the lateral geniculate nucleus, located in the occipital lobe and responsible for early visual processing

Question 20

Retinotopic map

Answer 20

a point-by-point relation between the retina and V1

Question 21

Cortical magnification

Answer 21

the allocation of more space in the cortex to some sensory receptors than to others; the fovea has a larger cortical area than the periphery

Question 22

Simple cells

Answer 22

V1 neurons that respond to stimuli with particular orientations to objects within their receptive field; the preferred orientation of a simple cell is the stimulus orientation that produces the strongest response

Question 23

Orienting tuning curve

Answer 23

a graph that demonstrates the typical response of a simple cell to stimuli or different orientations

Question 24

Complex cells

Answer 24

neurons in V1 that respond optimally to stimuli with particular orientations; unlike simple cells, they respond to a variety of stimuli across different locations, particularly to moving stimuli

Question 25

End-stopped neurons

Answer 25

neurons that respond to stimuli that end within the cell's receptive field

Question 26

Ocular dominance column

Answer 26

a column within V1 that is made up of neurons that receive input from only the left eye or only the right eye

Question 27

Orientation column

Answer 27

a column within V1 that is made up of neurons with similar responses to the orientation of a shape presented to those neurons

Question 28

Hypercolumn

Answer 28

a 1-mm block of V1 containing both the ocular dominance and orientation columns for a particular region in visual space

Question 29

Blobs

Answer 29

groups of neurons within Vl that are sensitive to color

Question 30

Interblobs

Answer 30

groups of neurons that are sensitive to orientation in vision

Question 31

Extrastriate cortex (secondary visual cortex)

Answer 31

the collective term for visual areas in the occipital lobe other than V1

Question 32

V2

Answer 32

the second area in the visual cortex that receives input; often considered the area that starts with visual associations rather than processing the input (sometimes called the prestriate cortex)

Question 33

Ventral pathway

Answer 33

starts with midget and bistratified retinal ganglion cells and continues through the visual cortex into the inferotemporal cortex in the temporal lobe; often called the "what" pathway, as it codes for object identification as well as color vision

Question 34

Dorsal pathway

Answer 34

starts with parasol retinal ganglion cells and continues through the visual cortex into the parietal lobe; often called the "where" pathway, as it codes for the locations of objects and their movement

Question 35

Object agnosia

Answer 35

an acquired deficit in identifying and recognizing objects even though vision remains intact

Question 36

Inferotemporal cortex

Answer 36

the region in the temporal lobe that receives input from the ventral visual pathway; one of its functions is object identification

Question 37

MT (V5)

Answer 37

an area of the occipital lobe in the dorsal pathway, specific to motion detection and perception

Question 38

Blindsight

Answer 38

the presence of visual abilities even though a person experiences blindness because of damage to V1

Question 39

Scotoma

Answer 39

an area of partially or completely destroyed cells, resulting in a blind spot in a particular region of the visual field

Question 40

Internuclear ophthalmoplegia

Answer 40

a conjugate palsy resulting from damage to the brain stem region known as the medial longitudinal fasciculus

Question 41

What is another name for the primary visual cortex?

Answer 41

area 17

Question 42

Which of the following is associated with the dorsal pathway?

Answer 42

locations

Question 43

Each layer of the lateral geniculate nucleus receives input from only one eye. T/F

Answer 43

True

Question 44

In ______, damage to the brainstem affects the ability of both eyes to train on the same object.

Answer 44

conjugate gaze palsy

Question 45

The ventral pathway is also known as the ______ pathway.

Answer 45

"what"

Question 46

The M pathway is also known as the ______ pathway.

Answer 46

dorsal

Question 47

Hubel and Wiesel discovered that neurons in the brain ______.

Answer 47

respond to only some patterns of stimuli

Question 48

End-stopped neurons are neurons that respond to stimuli that end outside the cell’s receptive field. T/F

Answer 48

false

Question 49

Nora sustains damage to part, but not all, of her primary visual cortex. Which disorder is most likely to result from this injury?

Answer 49

scotoma

Question 50

Why does the fovea take up so much space in the cortex?

Answer 50

The fovea specializes in sending information necessary for acuity-reliant functions, such as object identification.

Question 51

Why would hte visual system represent visual space -- what function does it serve?

Answer 51

The visual system represents visual space as it perceives the location of objects to ensure our safety in different surroundings. This also helps us to be able to coordinate our movements. In continuation it also helps us create a perceive images, and depth of objects to judge distances that we see.

Question 52

Describe the relation of the retinotopic organization to the representation in the external world.

Answer 52

Retinotopic organization mirrors the external world as retinal ganglion cells from adjacent areas of the retina connects to cells that are in adjacent areas within the LGN.

Question 53

What are the functions of V3, V4 and V5 (MT)? What might happen if these areas are damaged?

Answer 53

V3 is an area that perceives movement and depth perception, where damage to the area can result to an impairment to these functions. V4 recognizes shapes, as the neurons are sensitive to binocular disparity, and it also plays a role in color vision since if its damaged color vision will be affected. V5 neurons are sensitive to the direction and speed of motion. If this area were to be damaged the individual would not be able to perceive motion.

Question 54

Why would color information be important for the ventral pathway but not the dorsal pathway?

Answer 54

Color information is important for the ventral pathway since it goes through V2 & V4, which are areas that have thin stripes that respond to color, while the dorsal pathway focuses on movement and location of objects.