The Retinostriate Pathway

Question 1

How many layers does the striate cortex have?

Answer 1

Contains 6 layers (1, ⅔, 4A, 4B, 4C, 5, 6)

Question 2

Cortical Magnification

Answer 2

The amount of cortical area that is dedicated to a particular area of the visual field.

Question 3

Eccentricity

Answer 3

Term referring to the angular distance from the centre of the visual field or from the fovea of the retina

Question 4

What is one important consequence of cortical magnification?

Answer 4

Visual acuity declines in an orderly fashion with eccentricity

Question 5

Visual Crowding

Answer 5

Inability to recognize a target object in clutter

Question 6

What are the receptive fields of striate cortex neurons like? And what do you respond to?

Answer 6

They are not circular like the retina or LGN but rather they are elongated and respond vigorously to bars, lines, edges and gratings than to round spots of light

Question 7

Orientation Tuning:

Answer 7

Tendency of neurons in the striate cortex to respond optimally to certain orientations and less to others

Question 8

Individual neuron in the striate cortex responds best when?

Answer 8

The line or edge is at the right orientation

Question 9

What types of orientation do most cells respond to?

Answer 9

More cells are responsive to horizontal and vertical orientations than to obliques

Question 10

Cortical cells are much more narrowly ______and respond to smaller range of _______ than retinal ganglion cells

Answer 10

tuned ; spatial frequencies

Question 11

Cortical cells respond especially well to moving ______, ______, ______ and ______

Answer 11

lines, bars, edges and gratings

Question 12

Cortical cells respond strongly when a line moves in _____ but not when the same line moves _______

Answer 12

one direction (left to right), right to left

Question 13

Ocular dominance

Answer 13

Property of receptive fields of striate cortex neurons in which they tend to prefer visual input from one eye over the other

Question 14

Are cells in striate cortex influenced by input from one or both eyes?

Answer 14

Cells in the striate cortex can be influenced by input from both the right and left eye

Question 15

Difference in response of complex and simple cells?

Answer 15

A complex cell will respond regardless of where the stripe is presented as long as it is somewhat within the cell’s receptive field whereas the simple cell will respond only if a stripe is presented to the center of its receptive field

Question 16

End-Stopping:

Answer 16

The process by which a cell in the cortex increases its firing rate as the length of a bar increases until the bar fills up its receptive field,and then it decreases its firing rate as the bar is lengthed further

Question 17

How does the size of a particular cell’s receptive field appears to vary with target contrast?

Answer 17

Cell might respond to a smaller portion of the visual field when the grating stimulus has a high contrast than it will when the difference between light and dark bars is more subtle

Question 18

Adaptation

Answer 18

A reduction in response caused by prior or continuing stimulation

Question 19

What does adaptation result in?

Answer 19

Both a decrease in firing rate and a change in the tuning curve

Question 20

Gratings at which orientation elicit the strongest response from the 0 degree selective cells?

Answer 20

Gratings orientated at 0 degrees (vertical) will elicits the strongest response from the 0 degree selective cells

Question 21

Spatial frequency adaptation is ______selective, thus there is little or no effect on sensitivity to ______following adaptation to a ______

Answer 21

orientation ; vertical gratings ; horizontal grating

Question 22

Selective adaptation causes which type of neurons to become fatigued?

Answer 22

Selective adaptation causes the neurons most sensitive to the adapting stimulus to become fatigue

Question 23

What type of neurons are not fatigued by the adaptation procedure?

Answer 23

Neurons responsive to much higher or lower spatial frequencies are not fatigued by the adaptation procedure so contrast sensitivity for these spatial frequencies is not affected.

Question 24

Why would the visual system use spatial frequency filters to analyse images?

Answer 24

Different spatial frequencies emphasize different types of information
- Low frequencies= empahisize broad outlines
- High frequencies- fine details

Question 25

High frequencies of an image are:
Low frequencies are:

Answer 25

quick abrupt changes from light to dark
large slow changes from light to dark over a large region

Question 26

Tilt Aftereffect

Answer 26

Perceptual illusion of tilt, produced by adapting to a pattern of a given orientation.

Question 27

Optic Disck

Answer 27

Represents the beginning of the optic nerve and is the point where the axons of retinal ganglion cells come together

Question 28

Optic Nerve

Answer 28

Sends visual information from your retina to your brain

Question 29

Fill in the structures of the visual pathway, from where ganglion cell axons exit the retina at the optic disk to the visual projection areas in the brain.

Answer 29

1) Optic Nerve
2) Optic Chaism
3) LGN (lateral geniculate nucleus
4) Optic Radiation
5) Visual (straied) Cortex

Question 30

Optic Radiation

Answer 30

Contains axons from the neurons in the lateral geniculate nucleus to the primary visual cortex.

Question 31

Visual Cortex

Answer 31

This is where images received from your retina begin to get processed and then sent out to other brain regions

Question 32

Layers that receive signals receive signals from the nasal half of the left retina are

Answer 32

layers 1, 4, and 6 in the right LGN

Question 33

Layers that receive signals from the retinal ganglion cells of the left eye that respond to colour.

Answer 33

left LGN, layers 3 and 5; and right LGN, layers 4 and 6

Question 34

Layers that receive signals that pass through the right optic nerve

Answer 34

left LGN: 1, 4, and 6;
Right LGN, layers 2, 3, and 5