Intro arrow 2. Rods & Cones arrow 2.3 Ganglion & Bipolar
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0. Left & Right Brain
1. Masking Alpha Channel
2. Rods & Cones
3. LGN: Magno & Parvo
4. SC: Superior Colliculus
5. Primary Visual Cortex
6. Dorsal - Ventral Stream
7. Eye Movements
8. Oculomotor System
9. Balance System
10. Ectopia & Microgyrus
11. Genetic Etiology
12. Reading
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14. Conclusion / Solution
15. Different Theories
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2.3 Ganglion and Bipolar Cells

Ganglion Cells receive visual information from Photoreceptors (Rods & Cones) via various intermediate cells such as Bipolar Cells, Amacrine Cells, and Horizontal Cells. Their axons form the Optic Nerve and connect approximately for 80% to the LGN (Lateral Geniculate Nucleus) and for 20% to the SC (Superior Colliculus).

There are 5 main types of Ganglion cells:


1. Midget Cells:

  • "Midget" based on the small sizes of their dendritic trees and cell bodies.
  • 80% of retinal ganglion cells.
  • Project to the Parvocellular layers of the LGN: P-cells
  • Mostly in the Fovea and receiving mainly Cones input.
  • Process Colour (Red & Green), Form and Fine details.


2. Parasol Cells:

  • "Parasol" based on the large sizes of their dendritic trees and cell bodies.
  • 10% of retinal ganglion cells.
  • Project to the Magnocellular layers of the LGN: M-cells
  • Mostly in the Periheral-retina and receiving mainly Rods input.
  • Process Motion and Orientation.

3. Bistratified Cells:

  • "Konio" means “as small as dust”, verry small sized.
  • 10% of retinal ganglion cells
  • Project to the Koniocellular layers of the LGN: K-cells
  • Very large receptive fields that only have centers (no surrounds) and receive input from intermediate numbers of Rods and Cones.
  • Process Colour (Blue & Yellow)

4. Photosensitive cells:

  • They contain their own photopigment, melanopsin, which makes them respond directly to light even in the absence of Rods and Cones.
  • Contribute to the regulation of pupil size and other behavioral responses to ambient lighting conditions.
  • Project to the Circadian Pacemaker of the brain: the Supra Chiasmatic Nucleus (SCN) (Circadian Rhythm = 24-hour cycle in the physiological processes of living beings)


5. Other Cells projecting to the LGN for eye movements (saccades)

  • Projecting to the LGN and cells making connections with the Edinger-Westphal Nucleus
  • This EWN supplies fibers to the eye, constricting the pupil and accommodating the lens.
Retinal Layers
Some Bipolar Cells are depolarised by light (on-bipolar cells) and others are hyperpolarised by light (off-bipolar cells). Bipolar cells synapse with Ganglion cells, in which action potentials can be generated, so that each Ganglion cell has a circular receptive field comprised of many Photoreceptors.

  • On-centre cell: A central excitatory area surrounded by an inhibitory area, forming an on-centre, off-surround receptive field.
  • Off-centre cell: A central inhibitory area surrounded by an excitatory area, forming an off-centre, on-surround receptive field.
  • Combined type of cell has a receptive field that is both stimulated and inhibited by light.


The diagram shows the relative firing rate of "on-" and "off-centre Ganglion cells" in the light and dark:


The purpose of this site is to present questions and new ideas about the above subjects.

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