[neilep (OP)]

Dearest Thinkologists,


See Quentin NanaConsumption The 3rd here ?

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He's a thoughtful fellow isn't he ?

See him there contemplating ?...you'd think he's considering the majestic wonder that is the Cosmos......... or perhaps some deep philosophical doctrine......instead he's debating should he rub his arse on a tree or just scratch it with his free hand !

I ponder this myself every day.

..........and so, whilst in deep thought, I wondered if the act of thinking actually burns a calorie or two ?...does the more complex the thought burn even more ?....or does it not burn any calories at all !


Ok..decision made....I'm gonna rub my arse against my neighbours tree....he probably won't notice as he has his chums in his garden having a BBQ !



Thanks


Neil
Arse Tree Scratcher

[RD]

With Positron Emission Tomography (PET) it is possible to map brain activity using radioactive glucose.
Demonstrating that when brain areas are active they consume more glucose.
So yes, thinking does burn a few more calories.   

http://en.wikipedia.org/wiki/Neuroimaging

[neilep (OP)]

With Positron Emission Tomography (PET) it is possible to map brain activity using radioactive glucose.
Demonstrating that when brain areas are active they consume more glucose.
So yes, thinking does burn a few more calories.   

http://en.wikipedia.org/wiki/Neuroimaging

Fantastic !!

THANK EWE RD

This encourages me to think some more and do lots of it too !

I suppose the next question I need to know the answer is...is how many calories does ' thinking ' burn ?....lets say a good 5 minutes deep thought !!

[RD]

I suppose the next question I need to know the answer is...is how many calories does ' thinking ' burn ?....lets say a good 5 minutes deep thought !!

I estimate going from vegetating to cerebrating for 5 minutes will increase energy consumption by about 1 Calorie.

Average power consumption of human brain is 20 Watts
http://hypertextbook.com/facts/2001/JacquelineLing.shtml

I guess that intense thinking increases power consumption to 30 Watts (probably overestimate).

10 Watts increase for 5min is 3000 joules.

1 Calorie (1 Kilocalorie) is 4184 joules.

An apple contains about 50 Calories.

If you thunk hard for 18 hours a day, rather than vegetating, it would burn an additional amount of energy equivalent to three apples.

[chris]

I'm not so sure. The brain is pretty much constantly active throughout the day; what alters with activity is the region of the brain being used. So when you switch from one task to another the region involved in orchestrating that task becomes slightly more active, but other, now less-employed brain areas have a corresponding reduction in activity.

Hence, I don't think that thinking burns that many more calories over baseline. Techniques like PET and fMRI / BOLD are looking at the difference in blood flow, rather than absolute levels of perfusion.

chris

[RD]

The reversing checkerboard stimulus induced large increases in regional blood flow to visual cortex...
activation resulted in a normalized visual cortex CBF increase of 35.6%

http://www.pnas.org/cgi/reprint/98/12/6859.pdf

35.6% increase, so that's two apples not three.

It's certainly not possible to think yourself thin.

[chris]

"Techniques like PET and fMRI / BOLD are looking at the relative difference in blood flow, rather than absolute levels of perfusion."

The point is not that some areas increase their perfusion when they become active - that's absolutely true - but instead that there is a dynamic shift in perfusion away from less active areas to favour slightly more active areas. Thus the overall cerebral flow rate is roughly constant, irrespective of the task since very few tasks recruit all brain modalities at once.

In the example you cite, the researchers gave subjects a strong visual stimulus to look at. Relative to when there were attending elsewhere their visual system increased its activity 35%.

But what is not reported is how other areas of the brain showed a reduced perfusion because they became correspondingly less active. These results are all relative.

Chris

[neilep (OP)]

Thank You Chris for your fascinating information....it's 'thought' provoking stuff indeed !