Exam 3: Sensation and Perception of Visual Signals

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The magnocellular and parvocellular neurons of the lateral geniculate nucleus (LGN) in the thalamus have several anatomical differences.

Magnocellular neurons are larger in size and have faster conduction velocities compared to parvocellular neurons. They also have larger receptive fields and are more sensitive to low contrast and fast-moving stimuli. In contrast, parvocellular neurons are smaller in size and have slower conduction velocities. They have smaller receptive fields and are more sensitive to high contrast and stationary stimuli.

Additionally, the two types of neurons receive input from different types of retinal ganglion cells. Magnocellular neurons receive input from the parasol retinal ganglion cells, which are sensitive to motion and have low spatial resolution. Parvocellular neurons, on the other hand, receive input from the midget retinal ganglion cells, which are sensitive to color and have high spatial resolution.

Overall, these anatomical differences contribute to the different functional roles of magnocellular and parvocellular neurons in processing visual information, with magnocellular neurons being more involved in motion detection and parvocellular neurons being more involved in color and form perception.