Brain energy expenses

dag.stenberg at helsinki.nospam.fi dag.stenberg at helsinki.nospam.fi
Fri Aug 18 03:04:14 EST 2000


Alexandre Blais <Alexandre.Blais at crchul.ulaval.ca> wrote:
> I was wondering if it is possible to measure the amount of energy
> expense (in joules) of the human brain when it is "at work"  

> -the main method of evaluating the metabolic activity of the brain is
> via MRI and PET using analogs of glucose

Or MR spectroscopy (to look at metabolites). All these methods are 
reasonably noninvasive, and improve all the time. 

> -it is possible to evaluate the contribution of different celle types in
> the brain, and to analyze the metabolic activity of different parts of
> the brain

The spatial resolution is yet not very impressive. The chunk of brain that
metabolism can be measured from contains numerous different types of
neurons, communicating with each other and other locations, and the
measures of metabolism do not really tell much about what is going on in
there. 

> However, I found no papers describing and measuring the total energy
> expense of the brain during "intellectual work" per unit time. 

As mentioned by Richard Norman, the total energy expenditure of the
brain does not change much with intellectual work, it is mainly a
redistribution of activity. This has been known since early measurements
in the 70's.

Dag Stenberg






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