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
Vision
This topic has expert replies
- Mission2012
- Master | Next Rank: 500 Posts
- Posts: 184
- Joined: Sun Aug 19, 2012 10:04 pm
- Thanked: 10 times
- Followed by:2 members
- KapTeacherEli
- GMAT Instructor
- Posts: 578
- Joined: Tue Aug 25, 2009 6:00 pm
- Thanked: 136 times
- Followed by:62 members
Why does it imply this? It could imply a defect in the visual cortex, after all!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.
- Mission2012
- Master | Next Rank: 500 Posts
- Posts: 184
- Joined: Sun Aug 19, 2012 10:04 pm
- Thanked: 10 times
- Followed by:2 members
People with normal vision would not have defect in visual cortex, isn't it?KapTeacherEli wrote:Why does it imply this? It could imply a defect in the visual cortex, after all!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.
If you find my post useful -> please click on "Thanks"
- KapTeacherEli
- GMAT Instructor
- Posts: 578
- Joined: Tue Aug 25, 2009 6:00 pm
- Thanked: 136 times
- Followed by:62 members
A defect related to melatonin production might have no effect on vision.Mission2012 wrote:People with normal vision would not have defect in visual cortex, isn't it?KapTeacherEli wrote:Why does it imply this? It could imply a defect in the visual cortex, after all!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.
-
- Junior | Next Rank: 30 Posts
- Posts: 29
- Joined: Mon Jan 16, 2012 9:22 pm
- Location: India
- Thanked: 1 times
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.
Else visual cortex dont have any relation whatsoever with gland's functioning.
-
- Senior | Next Rank: 100 Posts
- Posts: 30
- Joined: Sat Aug 24, 2013 10:46 am