brain antedation (Libet) implications

John H. johnh at faraway.xxx
Wed Mar 19 04:44:29 EST 2003


A throw in:

Libet's expt demonstrated that awareness and consciousness are not
synonymous. When we become conscious of something, we have already been
aware of that something. "We" is not quite right, our brains are aware of
that something. When that something is brought into consciousness, it's time
reference is also brought into awareness. So the brain has no need to ante
date an event, it already knows when the event occurred, it's just telling
'you' when that happened. No mystery.

This, I believe, is what Peter F is basically driving at.


John.

"harkyl" <kharvey06 at hotmail.com> wrote in message
news:a678be79.0303161121.303e5090 at posting.google.com...
> I have posted this thread at a forum I more frequently visit.  It
> brought no reply.  I regret if Libet's brain antedation has been
> pounded into oblivion here, but would be obliged for any additional
> interpretation or conclusion.  What follows is a brief review of
> Libet's findings followed by a conclusion/questions.
>
> There is a separation (in time) of conscious awareness from
> electrochemical events in the brain as shown by by Libet et al.
>
> It has been shown that conscious sensation does not occur immediately
> as neuronal electrochemical signals reach the cerebral cortex.  When
> the signal reaches the cortex, there is an incubation period during
> which there is propagation and attenuation of the neuronal
> transmission until it reaches the appropriate level before awareness.
>
> This period may be as long as .5s, but the self -conscious mind is
> shown to be able to antedate the perception so that it is perceived to
> happen up to .5s before the triggering neuronal event.  This process
> is called antedation.  The apparent paradox:  "My hand on the oven
> coil coincides with the pain I am aware of even though the time it
> takes to be aware of my hand burning takes .5s from the time the
> signal had reached the cortex".  Keeping in mind that actual neuronal
> transmission (long tract nerve fibers) is around .015s from skin to
> cerebral cortex as shown by evoked potential (EP):  added to the .5s
> of cortical activity before it can be experienced, it should take
> .515s before being aware of the pain.  However the event is antedated
> by being referred in time to the initial evoked response of the
> cortex.  Thus only seeming to take the .015s from long tract fibers to
> cortex.
>
> It is agreed that a conscious experience does not 'light up' as soon
> as impulses in some sensory pathway reaches the primary somatosensory
> areas in the cerebral hemisphere.  But our conscious awareness some
> how tricks us into thinking our hand burned coincidently in time with
> our awareness of it.  This anomaly seems to strengthen the dual nature
> of mind brain.  Perhaps this anomaly is the result of a conceptual
> error.  Does it also question Kantian time as a priori valid?
>
> Kyle





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