Brain energy expenses

thanks sorry at
Thu Sep 21 16:23:43 EST 2000

TV set as the brain is an interesting analogy. I would use it in a slightly
different way. Alertness vs. unoriented states (such as sleep) may be more
like it is tuned to the channels with programs vs. channels with white
noises. Energy consumption would be about the same as long as the TV set is
power-on. From the oxygen comsumption studies (which reflect energy
consumption assuming aerobic metabolism) there is only about 10% difference
total (brain as a whole entity) among different states with various levels
of consciousness.
In wakefulness the brainstem sends out tonic activating signals to thalamus
and cortex, as well as phasic firings specifically from aminergic cell
groups associated with novel stimulation from the environment, both to
increase the signal-to-noise ratio of sensory information processing.
During REM dreaming, the tonic activation from reticular formation is there
but the aminergic cell groups (except dopaminergic) are all silent,
corresponding to the amnesic & psychotic-like off-line processing of the

Jo Hsieh
johsieh @ ucdavis dot edu

Bill Browning wrote:

> Richard Norman <rsnorman at> wrote in message
> news:rvVm5.17922$%P2.1619744 at
> [snip]
> > Perhaps an analogy might be to consider the overall energy use by
> > television sets during the political conventions vs. during a "normal"
> > evening.  Specific subpopulations might change their television usage
> > during this time, and other subpopulations might change which specific
> > channel is being watched, but the overall energy consumption in a large
> > city probably doesn't change by a detectable amount.
> > [snip]
>      In the early days of television, I lived in a small town where there
> was only one TV station accessible and no cable or satellite.  When there
> was a commercial break in a popular program, the water pressure would
> decrease, because everybody flushed their toilets at the same time.
>      Perhaps the small-town analogy would be like an abnormal person who
> focused all his attention on one thing.  ??

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