jander at OSPREY.UNF.EDU ("John E. Anderson") writes:
>> One MEDLINE abstract I found says that the brain's energy consumption is
> twice that of the heart, for example. Does anyone have a list of what
> brain processes use all this energy? Does maintaining the ionic gradient
> across membranes consume most of it? What proportion is used by
> processes that reorganize or change the weights of synaptic connections?
The answers are not known in detail. It's an important question,
because the methods used for imaging brain activity actually look at
energy consumption, not activity per se. Consequently, the literature
on PET and functional MRI contains the most up-to-date information on
this topic. The consensus, as I understand it, is that most of the
energy consumption is related to synaptic transmission, but as to
which subcomponents are crucial, I'm not sure anybody knows. In any
case, reorganization of weights is not likely to consume a significant
amount of energy, compared to other processes.
-- Bill