Magnocellulaire

Magnocellulaire refers to a specific type of neuronal cell found in the retina and the lateral geniculate nucleus (LGN) of the thalamus. These cells, also known as M-cells or magnocellular neurons, are characterized by their large cell bodies and dendritic trees. In the retina, magnocellular ganglion cells are one of the two main types of output neurons, the other being parvocellular ganglion cells. Magnocellular cells receive input primarily from rods and some cones in the retina, contributing to a system that is highly sensitive to low light levels and rapid changes in visual information.

The magnocellular pathway is primarily involved in processing information related to motion, flicker, and depth perception. They have large receptive fields, meaning they respond to stimuli over a wider area of the visual field. This characteristic allows them to efficiently detect movement across a broad range. Magnocellular neurons have a fast conduction velocity, enabling rapid transmission of visual signals to the brain. Their response to visual stimuli is transient, meaning they fire strongly when a stimulus appears or changes but quickly adapt and stop firing if the stimulus remains constant.

In the LGN, magnocellular neurons are located in the ventral layers, receiving input from retinal magnocellular ganglion cells. From the LGN, these signals are projected to the primary visual cortex (V1) and then to other visual processing areas in the brain. The magnocellular pathway is crucial for our ability to perceive dynamic aspects of the visual world, playing a vital role in detecting and reacting to moving objects.