The Midget and Parasol Channels - MIT OpenCourseWare...The perception of brightness in photopic...

The Midget and Parasol Channels

1

Retinal ganglion cells, cross section, Golgi label

Image removed due to copyright restrictions.

Please refer to lecture video or Figure 4 from Schiller, Peter H. "Parallel information processing channels created in the retina." Proceedings of the National Academy of Sciences 107, no. 40

(2010): 17087-17094.

by Polyak2

Images removed due to copyright restrictions.

3

Please refer to lecture video or Figure 2c and 3c of Watanabe, M., and R. W. Rodieck. "Parasol and midget ganglion cells of the primate retina."

J 189, no. 3 (1989): 434-454.

Projections of the retinal ganglion cells

10

Cortical projections from LGN

123456

1-2 = magno3-6 = parvo

P

M

K2V1

Lamina:

interlaminar

LGN

K1 ?

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11

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The central connections of the midget

and parasol channels

12

14

60-

40-

20-

80-

60-

40-

20-

80-

60-

40-

80-

60-

40-

20-

20-

80-

60-

40-

20-Sp

ikes

per

bin

Normal

Parvo Injection

Magno Injection

Paired Injection

Recovery

Vl complex cell response to moving light bar

Image by MIT OpenCourseWare.

15

Time (msec)Time (msec)

00 15891593

46 36

46 36

BeforeBlock

AfterBlock

Magno Block Parvo Block

Recording in V4


16

Time (msec)Time (msec)00

BeforeBlock

AfterBlock

Magno Block Parvo Block

59

59

179

179

963 963

Recording in MT


1.0

0.8

0.6

0.4

0.2

0.0

V4 MT

Parvocellular BlockMagnocellular Block

Aver

age

bloc

king

inde

x

18


Lesion studies

20

Behavioral procedures

21

The lesions

26

Example of LGN lesions with ibotenic acid


27

Please refer to lecture video or Figure 4 of Schiller, Peter H., Nikos K. Logothetis, and Eliot R. Charles. "Role of color-opponent and broad-band channels in vision."

V 5, no. 4 (1990): 312-346.

PERCEPTUAL FUNCTIONS TESTED

Contrast Sensitivity Color Pattern

Texture

Shape

Stereopsis Flicker

Motion

Brightness

Scotopic Vision

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Contrast sensitivity

29

33

Contrast Sensitivity

0.1

0.2

0.3

Con

trast 0.4 Normal

MLGN Lesion0.5 PLGN Lesion

0.6

0.7

0.8

0.9

1 1.5 2 2.5 3

Spatial Frequency (cy/deg)


Color vision

34

36

100

90

80

70

60

50

40

30

20

10

0Normal PLGN MLGN

Seneca

Color DiscriminationPe

rcen

t Cor

rect


Brightness perception

37

The perception of brightness in photopic vision


39

Please refer to lecture video or Figure 16b,d of Schiller, Peter H., Nikos K. Logothetis, and Eliot R. Charles. "Role of color-opponent and broad-band channels in vision."

V 5, no. 4 (1990): 312-346.

The perception of brightness in scotopic vision


40

Please refer to lecture video or Figure 13 of Schiller, Peter H., Nikos K. Logothetis, and Eliot R. Charles. "Role of color-opponent and broad-band channels in vision."

V 5, no. 4 (1990): 312-346.

Pattern and texture perception

41

44

Texture Pattern

N P MN P M

100

9080

70

60

5040

30

20

10

Perc

ent C

orre

ct

Texture and Pattern Discrimination


Stereoscopic depth perception

45


47

Please refer to lecture video or Figure 1 of Schiller, Peter H., Geoffrey L. Kendall, Michelle C. Kwak,and Warren M. Slocum. "Depth perception, Binocular Integration and Hand-Eye Coordination in Intact and Stereo Impaired Human Subjects." 3:210.

Stereoscopic depth perception


48

Please refer to lecture video or Figure 22a,b of Schiller, Peter H., Nikos K. Logothetis, and Eliot R. Charles. "Role of color-opponent and broad-band channels in vision."

V 5, no. 4 (1990): 312-346.

Motion perception

49

53

V4 Lesion

Normal

Normal

Latencies:Normal = 318msMT Lesion = 362ms

Latencies:Normal = 234msMT Lesion =278ms

Eager

100

90

80

70

60

50

40

30

20

10

100

90

80

70

60

50

40

30

20

10

6 8 1210

6 8 12 1410

Percent Luminance Contrast

MT Lesion

Perc

ent C

orre

ct

Zeno

esion


Motion detection

The perception of flicker

54

57

90

80

70

60

50

40

30

20

10

0

5 8 10 15 20Flicker rate (Hz)

Flicker DetectionPe

rcen

t Cor

rect

Green Flicker

Normal

V4 LesionMT Lesion

Peachy

Red/Green Flicker

5 8 11 14 17 20 23 26


Flicker perception

Functions of the midget and parasol systems:

The midget system : color texture fine form fine stereo

The parasol system: fast flicker fast, low contrast motion

Both Systems: brightness coarse form coarse stereo slow flicker slow, high contrast motion scotopic vision

59

60

H

H

H

H

L

L

L

L

Proc

essi

ng C

apac

ity

Spatial Frequency

Temporal Frequency

Parasol SystemMidget System


Summary: 1. Two major channels originating in the retina are the midget and the parasol.

2. In central retina the receptive field center of midget RGC and parvocellular LGN cells is compised of a single cone.

3. Parasol cells have much larger receptive fields; the cone input is mixed in both the center and the surround.

4. The midget and parasol cell ratio from center to periphery changes from 8 to 1 to 1 to 1.

5. The midget and parasol systems converge on some of the cells in V1.

6. V4 receives input from both the midget and parasol cells.

7. The major input to MT is from the parasol cells.

8. The midget system extends the range of vision in the wavelength and high spatial frequency domains

9. The parasol system extends the range of vision in the high temporal frequency domain.

61

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