1. LGN & CORTEX
© Wesner, M. F.

2. Retinogeniculostriate (retina - thalamus - cortex)
Retinofugal projections - Pathway of optic nerve to brain called retinofugal (fugal meaning “to flee”).
A perceptual pathway:
Retinogeniculostriate (retina - thalamus - cortex)
V1 or striate cortex
Nonperceptual pathways:
Retinotectal (retina to superior colliculus)
Retinohypothalamic (retina - hypothalamus - pineal)

3. Part of the tectum:

4. Retinogeniculate and retinotectal projections

5. “Retinogeniculocortical” or “retinogeniculostriate” pathway – part of the retinofugal projection that mediates conscious visual perception.

7. On-Center; Off-Surround Cell in LGN
Historic movie footage of early single-cell recording in the cat visual system by David Hubel and Torsten Wiesel.

12. posterior
anterior
contralateral
ipsilateral

13. The projections of the small ganglion (PC cells) and large ganglion (MC cells) cells to the parvocellular and magnocellular layers of the LGN:
Acknowledgement:   Image from Webvision by Kolb, Fernandez and Nelson, courtesy of Matthew Schmolesky at Erasmus University, Rotterdam.

15. This means that all information in the right (left) visual field projects to the left (right) cortex.
This means ViSUAL INFORMATION is contralaterally represented.

17. = contralateral

18. Ocular Dominance 6 4 1

20. This begins to establish a retinotopic organization to the cortex.
NOTE: Point of activity within each layer align with the same retinal position in each eye (i.e., retinal correspondence).

22. A recently recognized, anatomically & functionally distinct third subdivision of the visual pathway, called the koniocellular (KC) pathway.

23. The properties of koniocellular cells have been studied in anthropoid primates, and their importance for human vision is only now becoming understood, particularly with respect to S-cone operations.

24. KC cells form thin layers that lie between the M and P layers
KC cells form thin layers that lie between the M and P layers..formally referred to as “intercalated layers”.

26. Generally, the spatial and temporal properties of the KC cells in primates fall between the parvocellular and magnocellular spatiotemporal properties..

27. Spatially, the KC cells are species specific
Spatially, the KC cells are species specific. Generally, however, they are tuned to spatial frequencies that are lower than the PC system but higher than the MC system.
Similarly, the temporal modulation (i.e., “timing”) sensitivity of KC cells are higher than PC but lower than MC cells.

28. The projections of the koniocellular cells to the primary visual cortex (V1) appear to be towards the cytochrome oxidase (CO) cortical blobs (i.e., cortical areas responsive to chromatic changes). KC cells are particularly responsive to “blue-yellow” differences (S-cone ON mediation). V1

29. Primary visual cortex (V1)
Brodmann 17
Striate cortex

30. The retinotopic organization of V1 (striate cortex) using 2-dg autoradiography

31. This begins to establish a retinotopic organization to the cortex.

34. Note: A retinotopic map can also be found in the superior colliculus of the tectum (in the midbrain), but the map is more distorted than at the cortex.

36. CORTEX: Simple Cells

42. CORTEX: Complex Cells

46. CORTEX (beyond V1): Hypercomplex or End-Stop Cells ?

48. Complex Cell End-Stop Cell Slit Length (deg visual angle)

49. Possible circuit for an end-stop cell
3 converging complex cells. - +

50. V1 (primary visual cortex):
Orientation columns

51. Look at a gyrus of the primary visual cortex (Area #17) or V1 or striate cortex.

54. 2-dg treated
Orientation Columns

55. V1 (primary visual cortex):
ocular dominance columns

56. Top View of OCULAR DOMINANCE COLUMNS
PRO* treated
Radioactive proline injected into the eye.
Top View of OCULAR DOMINANCE COLUMNS

58. Margaret Wong-Riley (1979) coined the term blobs.
Introduced labeled cytochrome oxidase (an enzyme used in cellular metabolism) and measured its migration to V1. Prominent blobs found in layer III of V1 cortex.

61. Granular
Agranular

63. Six Layers of the Striate Cortex (V1): Layer devoid of nuclei
Orientation, ocular dominance columns & (inter)blobs (input from 4A & 4Cb - PARVO)
Afferent Input-big sensory layer with ocular dominance columns
Input from PARVO & 4Cb
Input from 4Ca
Afferent Input
..from MAGNO (Mx & My cells)
..from PARVO (P cells: foveal chromatic & luminance signals)
Feedback to superior colliculus (visual motor)
Feedback to LGN (visual motor)
To V2 (thin stripes & pale stripes) & V4

64. ventral
dorsal
(Layers 3, 4,5, 6)

65. Six Layers of the Striate Cortex (V1): Layer devoid of nuclei
Orientation, ocular dominance columns & blobs (input from 4A & 4Cb - PARVO)
Afferent Input - big sensory layer
Input from PARVO & 4Cb
Input from 4Ca
Afferent Input
..from MAGNO (Mx & My cells)
..from PARVO (P cells: foveal chromatic & luminance signals)
Feedback to superior colliculus (visual motor)
Feedback to LGN (visual motor)
To V2 (thick stripes), V3 & MT (V5)

66. ventral
dorsal
(Layers 1,2)

67. Chromatic or luminance responsive
IVA
luminance responsive
Chromatic or luminance responsive

68. V2 (thin stipes)
interblobs
V2 (pale stipes)

69. Magno (MC) & Parvo (PC) projections
V4 (form, color, constancies)
Inferotemporal (high form)
Magno (MC) & Parvo (PC) projections
RIGHT
LEFT
RIGHT
LGN
V3 (movement, orientation, depth)
V5 (MT) (movement, dynamic form)
ipsilateral
right eye (OD)
contralateral
left eye (OS)

71. Parvocellular (PC) stream
A quick down & dirty:
Parvocellular (PC) stream
LGN Layers: 3, 4, 5, 6
V1: IVCb, IVA
V1 (layers II & III): blobs (chromatic) & interblobs (luminance) & orientation & some ocular dominance columns.
V2: thin stripes (chromatic) & pale stripes (luminance)
V4: (color, color constancy & form)
Inferotemporal: (form & color)
extrastriate

72. Koniocellular (KC) stream
A quick down & dirty (cont.):
Koniocellular (KC) stream
LGN Layers: intermediate (intercalated between all layers: 1, 2, 3, 4, 5, 6)
V1: Straight into layers II & III blobs (chromatic).
V2: thin stripes (chromatic)
V4: (color, color constancy & form) and..
V5 (MT): (motion, dynamic form)
Inferotemporal: (form & color) and..
Dorsal (movement)
extrastriate

73. Magnocellular (MC) stream
A quick down & dirty (cont.):
Magnocellular (MC) stream
LGN Layers: 1, 2
V1: IVCa, IVB
V2: thick stripes (luminance only)
V3: (motion, orientation, depth)
V5 (MT): (motion, dynamic form)
Dorsal (MST) (movement)
extrastriate

74. (Layers 3,4,5,6)

76. Extrastriate or

77. 2 major visual streams:
“WHERE” V1
#17
“WHAT”

78. Cortical damage (occipitotemporal): Apperceptive Agnosia
Cortical damage here:
Akinetopsia
Cortical damage here:
Achromatopsia
Cortical damage here:
Blindness
Cortical damage (occipitotemporal):
Apperceptive Agnosia
Cortical damage (fusiform gyrus):
Apperceptive Prosopagnosia

80. Do sensory pathways always involve such anatomical divisions of labor?
Multisensory operations generally occur at high-level associative cortical sites in the processing heirarchy.
Do sensory pathways always involve such anatomical divisions of labor? NO