What is the Difference Between Magno and Parvo Cells

The main difference between Magno and Parvo cells is that Magno cells are large, have thick axons, and collect input from many retinal cells, whereas Parvo cells are small, have thin axons, and contain less myeline.

Magno cells and parvo cells are two types of ganglion cells. They compress and transfer information generated by the corn cells in the retina.

Key Areas Covered

1. What are Magno Cells
– Definition, Structure, Function
2. What are Parvo Cells
– Definition, Structure, Function
3. Similarities Between Magno and Parvo Cells
– Outline of Common Features
4. Difference Between Magno and Parvo Cells
– Comparison of Key Differences

Key Terms

Magno Cells, M-Cells, P-Cells, Parvo Cells

What are Magno Cells

Magno cells or M-cells are the neurons located in the magnocellular pathway. They occur in the lateral geniculate nucleus (LGN) of the thalamus. Also, they are a component of the visual system, and they are also known as magnocellular due to the relatively large size of the cells. Additionally, the inner two layers of the lateral geniculate nucleus of the thalamus contain magnocellular cells. M-cells of the lateral geniculate nucleus receive input from the parasol ganglion cells. Also, they send information to the striate cortex. This is called the signaling through the M pathway.

Figure 1: Magno vs. Parvo Cells

Furthermore, Magno cells are responsible for color vision. They provide static, depth, and motion information. M pathway is essential for light/dark contrast detection. It is more sensitive when the spatial frequency is low. Also, M cells are essential for the detection of changes in luminance.

What are Parvo Cells

Parvo cells or P-cells are the neurons located within the parvocellular pathway. Here, the parvocellular pathway receives nerve signals from midget retinal ganglion cells. Also, it supplies to the striate cortex. Parvocellular refers to small cells. Additionally, the outer four layers of the lateral LGN of the thalamus are parvocellular cells. Synapses of the parvocellular pathway occur in the above four layers of the LGN. Visual information transmits to the visual cortex separately. The primary visual cortex receives optical information from parvocellular cells through relay cells.

Figure 2: Lateral Geniculate Nucleus (LGN) of the Thalamus

Similarities Between Magno and Parvo Cells

• Magno cells and parvo cells are two ganglion cells that compress and transfer information generated by the corn cells of the retina.
• They produce two separate pathways from the retina to the striate cortex.

Difference Between Magno and Parvo Cells

Definition

Magno cells refer to neurons located within the magnocellular layer of the lateral geniculate nucleus of the thalamus, while parvo cells refer to neurons situated in the parvocellular layers of the lateral geniculate nucleus (LGN) of the thalamus.

Significance

Magno cells are large, have thick axons, and collect input from many retinal cells, while parvo cells are small, have thin axons, and contain less myeline.

Response

Magno cells generate a transitory response, while parvo cells generate a sustained response.

Receptive Field

The receptive field is large in magno cells, while the receptive field is small in parvo cells.  

Motion Perception

Motion perception is maximum in magno cells, while motion perception is minimum in parvo cells.

High Spatial Frequency

High spatial frequency is minimum in magno cells, while high spatial frequency is maximum in parvo cells.

Low Spatial Frequency

Low spatial frequency is maximum in magno cells, while low spatial frequency is minimum in parvo cells.

Color

Magno cells see color, while parvo cells are monochromatic.

Response Latency

Response latency is short in magno cells, while response latency is long in parvo cells.

Temporal Resolution

Temporal resolution is fast in magno cells, while temporal resolution is slow in parvo cells.

Conclusion

In brief, Magno and parvo cells are two types of ganglion cells that occur between the retina and the striate cortex of the brain. Magno cells are large and contain thick axons. They generate a transitory response. Their receptive field is large, and motion perception is maximum. Its high spatial frequency is minimum, and its low spatial frequency is maximum. Also, Magno cells can see color. Magno cell’s response latency is short and temporal resolution is fast. In comparison, Parvo cells are small and contain thin axons. They generate a sustained response. Also, the receptive field is small in parvo cells. Motion perception is minimum in parvo cells. The high spatial frequency of parvo cells is minimum. But low spatial frequency is minimum in parvo cells. On the other hand, parvo cells are monochromatic. Additionally, response latency is long in parvo cells, and temporal resolution is slow in parvo cells. Therefore, the main difference between Magno cells and parvo cells is their structure and function.

References:

1. 3031, S. of P., & Olman, E. by Dr. C. (2022, January 1). Magnocellular and parvocellular pathways. Introduction to Sensation and Perception.

Image Courtesy:

1. “Magno Parvocellular Pathways” By Thomas.haslwanter – Own work (CC-BY SA 3.0) via Commons Wikimedia
2. “Lateral geniculate nucleus” By Jimhutchins – Own Work (CC-BY SA 3.0) via Commons Wikimedia