Magnocellular cells
| Magnocellular cell | |
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| NeuroLex ID | Magnocellular cell |
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Anatomical terminology
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Magnocellular cells, also called M-cells, are neurons located within the Adina magnocellular layer of the lateral geniculate nucleus of the thalamus. The cells are part of the visual system. They are termed "magnocellular" since they are characterized by their relatively large size compared to parvocellular cells.
Details of the flow of signaling from the eye to the visual cortex of the brain that result in the experience of vision are not fully understood and many aspects are subject to active controversy and the disruption of new evidence.
In the visual system, signals for the most part travel from the retina to the lateral geniculate nucleus (LGN) and then to the visual cortex. In humans the LGN is normally described as having six distinctive layers. The inner two layers, (1 and 2) are magnocellular cell (M cell) layers, while the outer four layers, (3,4,5 and 6), are parvocellular cell (P cell) layers. An additional set of neurons, known as the koniocellular cell (K cell) layers, are found ventral to each of the magnocellular and parvocellular layers. These layers were named this way because cells in the M layers of the LGN are larger than cells in the P layers.
M cells in the LGN receive input from parasol ganglion cells (which some neuroscientists call M cells), and P cells receive input from midget retinal ganglion cells (which some neuroscientists call P cells).
From the LGN, the M pathway continues by sending information to the interblob regions of the 4Cα layer of the V1 region of the visual cortex, also called the "striate cortex". Other cells in the striate are more influenced from signaling from P cells and yet others from K cells. As signals are passed to other regions of the cortex, the signals start to be less separate, more integrated, and more influenced by signals from other parts of the brain. While classically it is said that signaling through the M pathway ultimately flow out of the visual cortex through the dorsal stream and signaling through the P pathway ultimately flows to the ventral stream, subsequent studies have shown that both pathways influence both streams.
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Wikipedia