Spatial Vision: From Spots to Stripes. LGN

Question 1

Contrast

Answer 1

The difference in luminance between an object and the background or between lighter and darker parts of same object.

Question 2

Acuity

Answer 2

Smallest spatial detail that can be resolved.

Question 3

Cycle

Answer 3

For a grating, a pair consisting of one dark bar and one bright bar.

Question 4

Visual Angle

Answer 4

The angle subtended by an object at the retina.

Question 5

Sine Wave Grating

Answer 5

A grating with a sinusoidal luminance profile.

Question 6

Aliasing

Answer 6

Misperception of a grating due to undersampling.

Question 7

Spatial Frequency

Answer 7

The number of grating cycles in a given unit of space.

Question 8

Cycles per degree

Answer 8

The number of pairs of dark and bright bars per degree of visual angle.

Question 9

Contrast Sensitivity Function (CSF)

Answer 9

A function describing how the sensitivity to contrast (defined as the reciprocal of the contrast threshold) depends on the spatial frequency (size) of the stimulus.

Question 10

Contrat Threshold

Answer 10

The smallest amount of contrast required to detect a pattern.

Question 11

Phase

Answer 11

The relative position of a grating.

Question 12

Lateral geniculate nucleus (LGN)

Answer 12

A structure in thalamus, part of mid brain, that receives input from the retinal ganglion cells and has input and output connections to the visual cortex.

Question 13

Magnocellular Layer

Answer 13

Either of the bottom two neuron-containing layers of the lateral geniculate nucleus, the cells of which are physically larger than those in top 4 layers.

Question 14

Parvocellular layer

Answer 14

ANy of the top 4 neuron-containing layers of the LGN, the cells of which are smaller than those in bottom two layers.

Question 15

Konicellular Cell

Answer 15

A neuron located between m and p celllar layers of LGN

Question 16

Contralateral

Answer 16

Opposite side of body or brain

Question 17

Ipsilateral

Answer 17

Same side

Question 18

Tomographical mapping

Answer 18

Orderly mapping of the world in the LGN and V cortex.

Question 19

V1

Answer 19

Area of cortex that receives direct inputs from the LGN as well as feedback from other brain areas, responsible for processing visual information.

Question 20

Cortical magnification

Answer 20

AMT of cortical area devoted to specific region in visual field.

Question 21

Visual Crowding

Answer 21

The deleterious effect of clutter on peripheral object recognition.

Question 22

Orientation Tuning

Answer 22

Tendency of neurons in V1 to respond optimally to certain orientations and less to others.

Question 23

Ocular dominance

Answer 23

Property of receptive fields of V1 neurons by which they demonstrate a preference, responding somewhat more rapidly when a stimulus is presented in one eye than when it is presented in the other.

Question 24

Simple cell

Answer 24

a cortical neuron with clearly defined excitatory and inhibitory regions

Question 25

complex cell

Answer 25

a neuron whose receptive field characteristics cannot be easily predicted by mapping with spots of light.

Question 26

End stopping

Answer 26

The process by which a cell in the cortex first increases its firing rate as the bar length increases to fill up its receptive field, and then decreases its firing rate as the bar is lengthened further.

Question 27

Column

Answer 27

Vertical arrangement of neurons.

Question 28

cytochrome oxidase (CO)

Answer 28

An enzyme used to reveal the regular array of CO blocks.

Question 29

Adaptation

Answer 29

A reduction in response caused by prior or continuing stimulation.

Question 30

Ambylopia (Lazy eye)

Answer 30

A developmental disorder characterized by reduces spatial vision in an otherwise healthy eye, even with proper correction for refractive error.

Question 31

Strabismus

Answer 31

A misalignment of two eyes such that a single object in space is imaged on the fovea of one eye, and on the nonfoveal area of the other.

Question 32

Anisometropia

Answer 32

A condition in which the two eyes have different refractive errors.