Special senses: magnocellular visual pathway: practice question

A Physiology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Physiology · Special senses: magnocellular visual pathway

Sample item

A lesion selectively damages the magnocellular layers of the lateral geniculate nucleus on both sides. Which visual function is most affected?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Detection of motion and low-contrast stimuli

The magnocellular pathway carries information on movement, flicker and low-contrast stimuli, and has high temporal resolution. The parvocellular pathway carries colour and fine spatial detail.

Option by option

  • A. Pupillary constriction to light

    The light reflex runs through the pretectal nuclei, which bypass the lateral geniculate body.

  • B. Fine detail and red-green colour discrimination

    Fine detail and colour discrimination rely on the parvocellular layers.

  • C. Dark adaptation

    Dark adaptation depends on retinal photochemistry rather than the lateral geniculate nucleus.

  • D. Detection of motion and low-contrast stimuli (correct)

    Correct. The magnocellular stream mediates motion and low-contrast detection.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is D, Detection of motion and low-contrast stimuli. The magnocellular pathway carries information on movement, flicker and low-contrast stimuli, and has high temporal resolution.

Why is "Pupillary constriction to light" not the answer?

The light reflex runs through the pretectal nuclei, which bypass the lateral geniculate body.

Why is "Fine detail and red-green colour discrimination" not the answer?

Fine detail and colour discrimination rely on the parvocellular layers.

Why is "Dark adaptation" not the answer?

Dark adaptation depends on retinal photochemistry rather than the lateral geniculate nucleus.

What concept does this question test?

It tests Special senses: magnocellular visual pathway in Physiology. The parvocellular pathway carries colour and fine spatial detail.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Special senses: magnocellular visual pathway?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.