IUBio

Is it possible to read someone's mind?

yan king yin (at dot) y.k.y.lycos.com at hgmp.mrc.ac.uk
Sat May 19 08:07:29 EST 2001


"maxwell" <mmmaxwell at hotmail.com>:

>> [Babies] display the full spectrum of behavior.  Then the feedback of
>> emotions / drives etc causes "bad" circuits to be eliminated.
>
> Your evidence?

This is just a vague idea where alot of work is needed to make it more
substantial...

I gave one example where a person needs sleep after great expectations
followed by disappointment:  During the "generative phase" (eg Bob
thinks that he has won the lottery) the brain is "wired-up" by an
additive process.  In the "eliminative phase" (Bob finds out he's made
a mistake) the previous circuits have to be eliminated (which i suggest
is done during (?slow-wave?) sleep).

The generation of new circuits may be achieved by synaptogenesis or by
birth of new neurons (though the latter is rare in post-natal CNS).

>> (Postnatal brain development is characterized by a "rise and fall"
>> pattern, eg total number of synaptic connections plotted against age.
>
> _Prenatal_-- by postnatal the declining function is prevalent, though
> not in all CNS regions-- some are still on the upslope.

Yes... but the overall trend could be a result of both additive and
eliminative processes.

>> ie a feedback loop in multiple dimensions of love/hate/fear/etc/etc.
>
> Evidence?

On the one hand this statement is almost self-evident -- eg how kids
learn to walk (by trial and error), or in language acquisition (by
rewarding imitation), etc.  The question is whether we can find the
physical correlate of such a feedback mechanism:

ie  brain circuits generated randomly and subsequently eliminated/
stabilized by molecular signals that are correlates of "emotions".

>From the evolutionary perspective it is quite plausible that cognitive
function is achieved through feedback mechanisms, since it has the
advantage of being 1) completely flexible, and 2) economical in terms
of number of genes required to "code" it.

>> ...when one experiences great expectations followed by great
>> disappointment, one usually does not adjust to it immediately, but
>> has to "sleep it off".
>
> Presumably, in the self-same armchair from which you hypothesize?

go back to YOUR seat and calm down! =)

>> So maybe the brain is trying to rewire itself during sleep.
>
> Some support for this, but note that though hippocampal theta waves
> are most noticeably present in sleep, they are not absent in wakeful
> states, especially subsequent to perceptions of novel stimuli/circumstances.
> Frankly, the 'restorative/reorganizational' notion of sleep functionality
> has _some_ merit-- but surely fails to explain the ubiquity of sleep, or
> the wide cross-species and intraspecific variation in sleep stages, and
> absolute durations of sleep.

1. What do theta waves represent?  I dont know much about them except
that they characterize various levels of wakefulness.

2. If sleep is a process of reorganization, then surely all organisms that
has a complex CNS need sleep (in order for adaptive behavior to occur).

>> If the Hebbian view is correct, ...
>
>Which Hebbian view?

Hebb proposed in 1949 that "excitatory synapses are stabilized when they
successfully trigger action potentials in the postsynaptic cell".  That
formed the basis of the Hopfield (1982) learning rule, for artificial
neural networks.  Recently the discovery of NO and canabinoid (sp?) as
retrograde signaling molecules might prove that the brain does make use
of this type of learning rules.

Im suggesting that there might be generative/stabilizing/eliminative
processes acting on the synaptic level, and they are mediated by molecular
signals that correlate to our emotions.  i think this hypothesis can give
useful insight to cognitive behavior, modelling, and also be verified by
experiments.

Some claims:

1. massive synaptic connections were generated randomly at some point
(periodically (?during REM sleep?) or at birth).

2. this "primordial soup" generates totally random behavior (eg the baby
is not hungry, but it cries or kicks its legs everywhere etc).

3. molecular signals (whether intrinsic or extrinsic to the brain) are
the correlates of emotions and drives.  Such as availability of ATP or
glucose, hormones, growth factors, etc.

4. synapses are stabilized/eliminated according to these signals. The
effect of the signal *defines* the corresponding emotion as good/bad.
The 2 things are equivalent.  (From the evolutionary point of view,
each neuron/synapse carries the burden to prove that it is good for
the survival of the individual).

5. higher cognitive functions are possible when "reward" signals can
also be issued inside the brain, by complex networks of neurons that
function like an endocrine organ.

6. when a certain behavior gets an adverse response (pain, fear, etc),
all the recently generated circuits get "punished".  That they dont
get eliminated at once, allows for higher-order circuits to be
established.

7. this process goes on without the subject being conscious of it.
"Consciousness" emerges when enough molding has occured.

8. memory might be a by-product of this process when elimination is
spared for early established networks (just speculation!).

well.. i admit this is all very imprecise. I'm digging up more info to
elaborate on it.  please give your comments as well!

>> there should be some "basic" emotions that form the "basis set" of more
>> complex feelings.  For example, the feeling of fear is somewhat similar
>> to hunger and also to that of looking down from a tall building
>> (a thing known as synesthesia).
>
> You totally misuse the word.

I was trying to say that sometimes "abstract" feelings could get mixed up
with "gut" feelings.  It does not qualify the use of "synesthesia" defined
as the psychological disorder,  but i think that word can be used in a
broader sense.

>> To answer the original question -- there is as yet no way at all, to
>> stimulate the brain in any localized and noninvasive manner.  When new
>> techniques are available to do that, things might be alot different.
>
> This does not answer the original question, and your answer also reveals
> your ignorance of trans-cranial magnetic stimulation. Also, why in the
> world do you think that being able to locally stimulate the brain might
> help you "read someone's mind?"

i think TMS has low spatial resolution and it is also somewhat invasive
in that the subject feels an unpleasant pinch on the scalp.  I think the
diffusion of magnetic waves through the medium (brain) makes it very
difficult to get high resolution.  Maybe MRI techniques will provide a
solution because there is much progress there.

Well, I'm more interested in understanding the mechanisms of cognitive
function than to create the "mind-reading" machine.  That is just too
speculative from our standpoint at present. But, nothing is impossible =)






More information about the Neur-sci mailing list

Send comments to us at biosci-help [At] net.bio.net