Thank you for your comments, which I understand to pertain to the broad
spectrum of activity in the brain. I should perhaps have made it
clearer that I was referring to just a narrow part of that spectrum,
namely the 'gamma' range of frequencies of oscillation defined by the
authors in my references 5,6 and 7.
These and other researchers are tentatively identifying the rhythmic
and synchronised firing of certain groups of neurons in this gamma
range as the neural correlate of awareness of particular objects.
I propose only that mitochondria in certain circumstances might trigger
this rhythmic and synchronised firing in the gamma range.
The complex interaction of many nerve impulses arriving at the synapses
of one neuron from other parts of the brain is something I know nothing
about.
Regards,
Andrew Gyles
In article <908l3u$k5p$1 at mercury.hgmp.mrc.ac.uk>,
Rich Cooper <richcooper1 at mindspring.com> wrote:
> Andrew Gyles wrote:
>> [snip]
> > The question here is whether the ATPsynthase enzymes in a
mitochondrion
> > inside a neuron would allow minor floods of excess protons to leave
the
> > mitochondrion and cross a (small) gap to the inside of the membrane
of
> > the neuron. ATPsynthase might pass protons so quickly from outside
the
> > inner membrane of the mitochondrion to inside that no excess protons
> > could pass from the mitochondrion to the membrane of the neuron.
And it
> > is possible that the positive charge of the protons outside the
inner
> > membrane of the mitochondrion is balanced, partly or wholly, by the
> > negative charge of anions inside the inner membrane, so that the
> > protons on the outside are 'tied' by the attractive force between
them
> > and the anions. (That is to say, the inner membrane of the
> > mitochondrion might be partly or completely polarised when
> > ATPsynthase/ATPase is working as the synthase. I have no
information on
> > this.)
>> An interesting, and related, question is the neurological timing of
signals
> arriving at a single mitochondial site from different sources. Phase
> relationships in electrical signals result from time-of-flight of two
pulses
> impinging on one destination. For example, if Mary drives from LA
> to SF using route 101 (the ocean route), she takes about the same
> travel time each trip. If John drives from LA to SF using I-5, he
takes
> about the same time each trip also. So if they both leave LA in a
> synchronous temporal relationship repeatedly, they have a synchronous
> relationship of arrival in SF.
>> Suppose two impulses (one activating and one inhibiting) reach a
> neural mitochondrion. One can turn the 120 degrees clockwise,
> while the other turns 120 degrees couterclockwise. The result is
> just a temporary charge surplus, quickly wiped out by the second
> impulse to arrive.
>> > Because of the doubts outlined above I think it likely that, if
> > mitochondria are indeed the motors of consciousness, they trigger
the
> > rhythmic firings of certain neurons at the gamma frequencies only
when
> > the rotary enzymes are working as ATPases, fuelled by ATP and
pumping
> > protons from inside the inner membrane of the mitochondrion to
outside
> > it. I propose that when working thus they can produce
minor 'floods' of
> > excess protons that can quickly cross a small gap from the
> > mitochondrion to the inside of the membrane of a neuron.
The 'floods'
> > of protons arrive at a gamma frequency and trigger firings of the
> > neuron at the same gamma frequency. When the mitochondrion exhausts
(or
> > nearly exhausts) the supply of ATP inside it the ATPase has to stop
> > using ATP as a fuel; it then rotates in the reverse direction and is
> > driven as ATPsynthase by the flow of protons from outside the inner
> > membrane to inside.
>> Floods occur when a lot of Johns reach SF with no Marys to balance
> them.
>> > Thus the neuron will be triggered at a gamma frequency until the
> > mitochondrion runs out of ATP. Then the triggering will stop for a
> > while, while the mitochondrion 'recharges' its supply of ATP. This
> > explains the rhythmic pattern observed in the gamma oscillations.
>> The "rythms" are only vaguely synchronous. Look at an EEG for
> a while, and you see very little patterning. This is probably (IMHO)
> due to the switching of conscious contexts along the well known
> seven plus or minus two objects that we can hold in consciousness
> at one time.
>> > If mitochondria are the motors of consciousness because they can
drive
> > certain neurons each at a single gamma frequency characteristic of
that
> > neuron at any one time (or of a group of neurons of which it is a
> > member) it is possible that there has been natural selection for a
> > lower mitochondrial mutation rate in humans than in other animals.
This
> > is so because higher consciousness (especially the ability to use
> > language) gives humans many advantages in the struggle to survive
and
> > reproduce.
>> I don't see the connection. Our brains are simply larger, by a very
> big factor per unit body weight, than most other creatures. There is
> no reason to suspect a molecular difference when there is clearly a
> conceptual difference. Dolphi brains are big too, and dolphins
clearly
> have a conscious ability to learn, to communicate, and to adapt to
> their own evolved environment. There is no need to postulate that
> mitochondria are different in humans versus dolphins, or even versus
> ants. But the exploration of how ATP processing in mitochondria
> are universally related to neural functions might be a useful research
> path.
>> > Mutations (either maternally inherited or somatic) in mitochondrial
DNA
> > could produce populations of mitochondria that oscillated at
different
> > frequencies in certain single neurons important in the creation of
an
> > aspect of the conscious state. The driving of a single neuron at
two or
> > more different gamma frequencies would presumably destroy the
aspect of
> > consciousness that its firing would normally help to create.
>> Again, I don't see why multiple frequencies can't be a normal kind
> of operation. Each frequency can be superimposed on the whole
> signal, can be synchronous with a different island of neural partners,
> and still contribute to the conscious thought entertained. Multiple
> frequencies shouldn't confuse, or we wouldn't be able to get any
> radio or tv channel we tune to.
>> [snip]
>> Rich
>>
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