Week 4: Dorsal and Ventral Streams

Question 1

Low level of vision processing entails

Answer 1

local contrast, colour, orientation, movement

Question 2

Low level of vision processing is performed by

Answer 2

the retina

Question 3

Intermediate level of vision processing entails

Answer 3

analysis of the layout of the scenes - Distinguishing foreground from background

Question 4

Intermediate level of vision processing occurs in the

Answer 4

V1

Question 5

High level of vision processing entails

Answer 5

Object recognition and matching with memories

Question 6

Photoreceptors synapse with BPs in which layer

Answer 6

Outer plexiform layer

Question 7

BPs synapse with GCs in which layer

Answer 7

Inner plexiform layer

Question 8

Visual signal can be modulated in the outer later by which cells?

Answer 8

horizontal cells

Question 9

Visual signal can be modulated in the inner layer by which cells?

Answer 9

amacrine cells

Question 10

Optic radiations are formed by projections of neurons from

Answer 10

LGN

Question 11

Which layers of the LGN are dedicated to motion?

Answer 11

Layers 1 and 2 containing magnocellular neurons are dedicated to receiving input from M-type ganglion cells from the retina

Question 12

Magnocellular neurones from the LGN enter which layer of the V1 cortical area?

Answer 12

Layer 4C-alpha and subsequently Layer 4B

Question 13

Thick stripes of caused by cytochrome C staining reveal reveal areas of

Answer 13

neuronal input regarding motion from layer 4B of V1

Question 14

A lesion in the posterior inferior temporal lobe would result in which type of agnosia?

Answer 14

apperceptive

Question 15

A lesion in the anterior inferior temporal lobe would result in which type of agnosia?

Answer 15

associative

Question 16

Apperceptive agnosia

Answer 16

Ability to draw copy of object is impaired but verbal identification of object is not affected

Question 17

Associative agnosia

Answer 17

Can match or copy objects but cannot identify object

Question 18

The fusiform face area is located in the

Answer 18

inferior temporal lobe

Question 19

“Through” pathway of the retina

Answer 19

photoreceptors (rods/cones) synapse into bipolar cells which then synapse onto ganglion cells

Question 20

Transmission of visual Information to the train: the visual pathway

Answer 20

Axons of the ganglion cells in the retina form the optic nerve.
Most of the output of GC is located in the LGN in the thalamus.
Neurons of the LGN then send out their axons which form optic radiations to the visual cortex (V1)

Question 21

Role and mechanism of function of starburst amacrine cells

Answer 21

Inhibitory SBACs only release GABA when something moves along the dendritic tree in a particular direction
If the spot of light is moving along the dendritic tree towards the soma, no Ca2+ response and no GABA release
Thus, GABA is released when stimulus moves from soma to dendrite, but not when the spot moves towards the cell body (soma)
SBAC dendrites show calcium responses that differ along a dendrite.
Calcium signal is directional selective.
If BC are always firing and releasing NT and object is moving in preferred direction
Because the stimulus is moving from the periphery towards the cell body of the amacrine cell, GABA is not released, therefore excitation of GC
If the stimulus moves in the opposite direction (from the cell body), GABA is released and BP cells receive an inhibitory stimulus

Question 22

M (magnocellular ganglion cells) provide information regarding

Answer 22

motion

Question 23

P (parvocellular ganglion cells) provide information regarding

Answer 23

visual acuity, colour

Question 24

The most occipital/posterior part of the V1 allows us to see centrally or peripherally?

Answer 24

Centrally

Question 25

The more peripheral parts of the visual field are located more anteriorly or posteriorly along the calcarine fissure?

Answer 25

anteriorly

Question 26

Cortical magnification in the V1 refers to

Answer 26

The brain uses more physical space for signals from the fovea than periphery i.e. more of the visual cortex is dedicated to the central retina (macula) than to any of the peripheral parts

Question 27

Segregation of input in the V1

Answer 27

Layer 4Cα receives input from M layers of the LGN
Layer 4Cβ receives input from the P layers of the LGN
From the V1, information regarding motion travels from 4Cα to 4B and to the extrastriate areas

Question 28

Which layer of the V1 receives input from M layers of the LGN?

Answer 28

Layer 4Cα

Question 29

Which layer of the V1 receives input from P layers of the LGN?

Answer 29

4Cβ

Question 30

The output for layer 4B neurons that encode motion is

Answer 30

thick stripes of V2

Question 31

V1 blobs and V2 thin stripes are important in encoding information regarding

Answer 31

Colour

Question 32

The output for neurons from “thick stripe” area of V2 is

Answer 32

Area MT - middle temporal lobe

Question 33

Lesions in which area lead to deficits in pursuit eye movements

Answer 33

MST - middle superior temporal lobe

Question 34

Apperceptive agnosia occurs due to a lesion in which area?

Answer 34

Posterior inferior temporal lobe

Question 35

A lesion in the posterior inferior temporal lobe leads to which impairment?

Answer 35

Apperceptive agnosia - ability to match an object

Question 36

Association between area of the inferior temporal lobe and which other area is important for emotional association with objects/faces

Answer 36

Amygdala