Vision

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Vision

by Mission2012 » Sat Aug 17, 2013 9:15 am
Normally, the pineal gland governs a person's sleep-wake cycle by secreting melatonin in response to the daily cycle of light and darkness as detected by the eye. Nonetheless, many people who are totally blind due to lesions in the visual cortex of the brain easily maintain a 24-hour sleep-wake cycle. So the neural pathway by which the pineal gland receives information from the eye probably does not pass through the visual cortex.

For purposes of evaluating the argument it would be most useful to establish which of the following?

(A) Whether melatonin supplements help people who have difficulty maintaining a 24-hour sleep cycle to establish such a pattern

(B) Whether the melatonin levels of most totally blind people who successfully maintain a 24-hour sleep-wake cycle change in response to changes in exposure to light and darkness

(C) Whether melatonin is the only substance secreted by the pineal gland

(D) Whether most people who do not have a 24-hour sleep-wake cycle nevertheless have a cycle of consistent duration

(E) Whether there are any people with normal vision whose melatonin levels respond abnormally to periods of light and darkness

I chose E because if in people with normal eyes there is abnormality in response of melatonin level to light and darkness it implies that not information to glands is not passed through visual cortex but by some other means.

I don't know where i went wrong.

As answer is B
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by KapTeacherEli » Sat Aug 17, 2013 3:24 pm
Mission2012 wrote:
I chose E because if in people with normal eyes there is abnormality in response of melatonin level to light and darkness it implies that not information to glands is not passed through visual cortex but by some other means.
Why does it imply this? It could imply a defect in the visual cortex, after all!
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by Mission2012 » Sat Aug 17, 2013 8:37 pm
KapTeacherEli wrote:
Mission2012 wrote:
I chose E because if in people with normal eyes there is abnormality in response of melatonin level to light and darkness it implies that not information to glands is not passed through visual cortex but by some other means.
Why does it imply this? It could imply a defect in the visual cortex, after all!
People with normal vision would not have defect in visual cortex, isn't it?
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by mvijays01 » Sat Aug 17, 2013 9:44 pm

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by mvijays01 » Sat Aug 17, 2013 9:45 pm
is correct answer

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by KapTeacherEli » Sat Aug 17, 2013 9:46 pm
Mission2012 wrote:
KapTeacherEli wrote:
Mission2012 wrote:
I chose E because if in people with normal eyes there is abnormality in response of melatonin level to light and darkness it implies that not information to glands is not passed through visual cortex but by some other means.
Why does it imply this? It could imply a defect in the visual cortex, after all!
People with normal vision would not have defect in visual cortex, isn't it?
A defect related to melatonin production might have no effect on vision.
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Cambridge, MA
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by saurabhdhakad » Sun Aug 18, 2013 5:02 am
I believe ans should be B, because it the one that relates the Melatonin to Blind person.
Else visual cortex dont have any relation whatsoever with gland's functioning.

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by Nitin.811g » Sun Aug 25, 2013 1:32 am
B it should be IMO.[/spoiler]