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Discussion Starter · #1 ·
A 45-year-old man has abnormal circadian variation in body temperature, disruption of the sleep-wake cycle, and an impaired nocturnal surge of secretion of melatonin. An MRI of the brain is most likely to show a lesion involving which of the following nuclei?

(A) Accessory optic
(B) Lateral preoptic
(C) Pretectal
(D) Suprachiasmatic
(E) Supraoptic
 

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Answer is D

The suprachiasmatic nucleus or nuclei is a tiny region on the brain's midline, situated directly above the optic chiasm. It is responsible for controlling circadian rhythms. The neuronal and hormonal activities it generates regulate many different body functions in a 24-hour cycle.

The pretectum, also known as the pretectal area, is a region of neurons found between the thalamus and midbrain. It receives binocular sensory input from the retinae, and is the region responsible for maintaining the pupillary light reflex.
http://en.wikipedia.org/wiki/Neuron
 

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Discussion Starter · #6 ·
It seems that you are so in hurry posting and so you don't really read the replies. I already explained the matter above. I was even thanked for it!
err... thanks for yr reply. but it turns out u were in such a hurry to reply. I meant if someone could answer dr. marco's reply. why so cranky?

PS: when I post a question I look for explanations that members give because I cant find them. So I READ the replies and save them in my PC. :)
 
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