Lecture 14

Question 1

Where is the LGN located?

Answer 1

The dorsal thalamus

Question 2

How many layers of cells does the LGN have when viewed in cross section?

Answer 2

6

Question 3

The LGN is the gateway to…… and therefore to……

Answer 3

visual cortex; conscious visual perception

Question 4

Different types of retinal information are ____ _____ by the LGN

Answer 4

kept separate

Question 5

The LGN is the major target of…..

Answer 5

the two optic tracts

Question 6

Axons arising from M-type, P-type, and nonM-nonP cells in the two retinas synapse on……

Answer 6

Cells in different LGN layers

Question 7

In right LGN, right eye (__) axons synapse on LGN cells in layers….
Left LGN layers…

Answer 7

ipsilateral
2, 3, 5
1, 4, 6

Question 8

In right LGN, left eye (__) axons synapse on LGN cells in layers….
Left LGN layers…

Answer 8

contralateral
1, 4, 6
2, 3, 5

Question 9

LGN: inputs segregated by ____ and _____ type

Answer 9

eye; ganglion cell

Question 10

LGN:
Layers 1 and 2

Answer 10

Magnocellular LGN layers
Contain larger neurons, innervate by M-cells

Question 11

LGN:
Layers 3, 4, 5, and 6

Answer 11

Parvocellular LGN layers
Contain smaller cells, innervate by P-cells

Question 12

LGN:
ventral to each principal layer (K1-K6)

Answer 12

Koniocellular LGN layers
input from nonM-nonP retinal ganglion cells

Question 13

Synaptic input to LGN comes from ______, ______, and ______, the _____ is NOT the main source of synaptic input

Answer 13

Brain stem
Thalamus
Primary Visual Cortex

NOT mainly from retina

Question 14

Primary visual cortex provides ______ of the synaptic input to the LGN– role…….

Answer 14

80%
role not clearly identified

Question 15

“top-down” modulation may gate “______” input from LGN to….

Answer 15

“bottom-up”
primary visual cortex

Question 16

Brain stem neurons provide modulatory influence on…..

Answer 16

neuronal activity related to alertness and attentiveness

Question 17

LGN is more than……

Answer 17

A simple relay from the retina to the cortex

Question 18

Striate refers to the fact that area ___ has an unusually…..

Answer 18

V1
dense stripe of myelinated axons

Question 19

Other names for the primary visual cortex: (2)

Answer 19

V1; striate cortex

Question 20

Where is area V1 located?

Answer 20

the occipital lobe of the primate brain

Question 21

Brodmann’s area 17

Answer 21

area V1

Question 22

Just under pia mater
Largely devoid of neurons
Consists almost entirely of axons and dendrites of cells in other layers

Answer 22

Layer 1

Question 23

How are the layers of the Striate Cortex named?

Answer 23

Starting at white matter, named by roman numerals VI, V, IV, III, II, and I

Question 24

Three sublayers of layer IV; which sublayer is divided into two tiers, name tiers

Answer 24

IVA, IVB, IVC
Layer IVC divided into IVC(alpha) and IVC(beta)

Question 25

Inputs to the striate cortex (rough)

Answer 25

2 overlapping retinotopic projection maps Magnocellular LGN neurons Parvocellular LGN neurons Koniocellular LGN neurons

Question 26

Inputs to Striate cortex: Projection to layer IVC(alpha)

Answer 26

Magnocellular LGN neurons

Question 27

Inputs to Striate cortex: Projection to layer IVC(beta)

Answer 27

Parvocellular LGN neurons

Question 28

Inputs to Striate cortex: Make synapses primarily in layers I and III

Answer 28

Koniocellular LGN axons

Question 29

Intracortical connections: Layer IVC(alpha) projects mainly to cells in which layer?

Answer 29

Layer IVB

Question 30

Intracortical connections: Layer IVC(beta) projects mainly to cells in which layer?

Answer 30

Layer III

Question 31

Most intracortical connections extend ________ to the cortical surface along radial lines. This maintains the retinotopic organization established in layer ___.

Answer 31

Perpendicular; IV

Question 32

Intracortical connections: The axons of some layer_____ pyramidal cells extend collateral branches that make horizontal connections within layer _____

Answer 32

III; IIII

Question 33

Intracortical connections: _____ and _____ connections play different roles in the analysis of the visual world.

Answer 33

Radial and horizontal

Question 34

Layer IVC stellate cells project axons radially up mainly to layers _____ and _____

Answer 34

IVB and III

Question 35

All layer _____ receive input from only one eye, most neurons in layers __, __, __, and __ receive some amount of input from each eye.

Answer 35

IVC; II, III, V, and VI

Question 36

Neurons outside layer IV are organized into _____ _____ dominated by the left and right eye.

Answer 36

alternating bands

Question 37

The bands of cells extending through the thickness of the striate cortex are called _____ _____ ______.

Answer 37

Ocular dominance columns

Question 38

Studied with transneuronal autoradiograph from retina to LGN to striate cortex.

Answer 38

David Hubel and Torsten Wiesel (Nobel prize 1981)

Question 39

The left and right eye inputs are laid out as a series of alternating bands, like the stripes of a zebra.

Answer 39

Layer IV

Question 40

Outputs of Striate cortex: ________ cells send axons out of the striate cortex

Answer 40

Pyramidal

Question 41

Outputs of Striate cortex: Layer _____, _____, and ____ cells project to the superior colliculus and pons

Answer 41

II, III, and IVB

Question 42

Outputs of Striate cortex: Layer __ cells project to the superior colliculus and pons

Answer 42

V

Question 43

Layer ___ cells project back to the LGN

Answer 43

VI

Question 44

Cytochrome oxidase

Answer 44

Mitochondrial enzyme used for cell metabilism

Question 45

Blobs

Answer 45

Cytochrome oxidase-stained pillars in striate cortex running the full thickness of layers II, II, V, and VI (NOT IV)

Question 46

Cytochrome oxidase blobs: Sliced tangentially through layer ___, these spots appear like the spots of a leopard.

Answer 46

III

Question 47

Each blob is centered on an ocular dominance column in layer ____

Answer 47

IV

Question 48

Cytochrome oxidase blobs receive koniocellular inputs from ____ and parvocellular and magnocellular input form layer ____.

Answer 48

LGN; layer IVC

Question 49

The magnocellular pathway

Answer 49

analysis of object motion and the guidance of motor actions

Question 50

The parvo-interblob pathway

Answer 50

Analysis of fine object shape

Question 51

The blob pathway

Answer 51

Analysis of object color