Spatial Vision: From Spots to Stripes. LGN Flashcards Preview

Sensation and Perception > Spatial Vision: From Spots to Stripes. LGN > Flashcards

Flashcards in Spatial Vision: From Spots to Stripes. LGN Deck (32):
1

Contrast

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

2

Acuity

Smallest spatial detail that can be resolved.

3

Cycle

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

4

Visual Angle

The angle subtended by an object at the retina.

5

Sine Wave Grating

A grating with a sinusoidal luminance profile.

6

Aliasing

Misperception of a grating due to undersampling.

7

Spatial Frequency

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

8

Cycles per degree

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

9

Contrast Sensitivity Function (CSF)

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.

10

Contrat Threshold

The smallest amount of contrast required to detect a pattern.

11

Phase

The relative position of a grating.

12

Lateral geniculate nucleus (LGN)

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.

13

Magnocellular Layer

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.

14

Parvocellular layer

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

15

Konicellular Cell

A neuron located between m and p celllar layers of LGN

16

Contralateral

Opposite side of body or brain

17

Ipsilateral

Same side

18

Tomographical mapping

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

19

V1

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

20

Cortical magnification

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

21

Visual Crowding

The deleterious effect of clutter on peripheral object recognition.

22

Orientation Tuning

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

23

Ocular dominance

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.

24

Simple cell

a cortical neuron with clearly defined excitatory and inhibitory regions

25

complex cell

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

26

End stopping

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.

27

Column

Vertical arrangement of neurons.

28

cytochrome oxidase (CO)

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

29

Adaptation

A reduction in response caused by prior or continuing stimulation.

30

Ambylopia (Lazy eye)

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

31

Strabismus

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.

32

Anisometropia

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