Re: Specialization and Optimization Of Neural Organization By Selective Stimulation And Deprivati

Anders Sandberg ()
20 Nov 1997 00:28:59 +0100

Mike Coward <> writes:

> <Hej Anders, :-)


> >> >1:1- How do I induce plasticity?
> >
> >Training seems to be the usual way.
> That's too general a term for me.
> 1- How do I train for an intensification of neural plasticity?
> 1 1- What thoughts,
> 1 2- how hard,
> 1 3- how long?
> 1 4- How does blood pressure effect it?
> 1 5- How does diet effect it?
> How about calcium?

Good questions. You may have noted that it took me a while to answer
(I have piles of work), but it was worth it since I actually have some
real facts now. As a neuroscientist it is easy for me to give vague
answers about plasticity, but when I began to think about it things
became much harder.

Anyway, I listened to Michael Merzenich yesterday when he received an
award from the Stockholm Physiology Society. He talked about his
famous experiments on monkey sensory cortex, where he managed to
change the somatotopic map (the map between the skin of the hand and
the cerebral cortex) through training, and even blur the areas through
overtraining. By training something very hard, you can really expand a
sub-area at the expense of neighboring areas. Based on this research
he then began to study how to train children with language problems
and dyslexia, with some impressive results (his group was able to
bring even quite autistic children into the normal statistical
range). Furthermore, he appeared to be able to change some of the time
constants of their hearing, which in itself is an amazing fact.

What really makes the cortex plastic seems to be highly stereotyped
movements combined with attention - acetylcholine is likely
involved. Tension, high blood pressure and emotion can increase the
acetylcholine release. The problem here is that overtraining is in
general not something you want, it makes the brain *less* flexible and
more stereotyped, even if you become brilliant at certain
things. Still, it can be useful to "reformat" some cortex.

Some learning factors which are likely useful:

* Strong attention, high motivation
* Repetition
* Progressive training (it constantly becomes more challenging,
without becoming too challenging).
* Adaptive and customized training (it adapts to your performance)
* For each training session at each difficulty level, continue to
train until the results are satisfactory.

I don't know about calcium, but I guess it is not a good idea to have
too much or too little during training.

> >> >1:2- If there was hyperplasticity what would it be like,
> >> >short term memory?
> >
> >Do you mean a state of very high neural plasticity? In that case you
> >would likely learn fast but also forget fast, new memories would erase
> >old memories and stray thoughts would be remembered far too well.
> ...sounds like short-term memory.
> 1- What would mid-term memory be if anything?

What I'm researching :-) You are right, short-term memory is likely so
quick and plastic that it cannot hold much, while mid-term memory is
the parts of the brain that can keep an impression for a longer time
(say a few hours) until it can be encoded in permanent long term
memory. It seems that the medial temporal lobe (the hippocampus and
surrounding cortex) have this function.

> How can the mind become more sensitive to other frequencies
> (ie. radio, EM biofields)?

I don't think it can get more sensitive unless you start adding
antennas (not likely a good idea) or instruments (like a radio).

> 1- What do neurons that get used often for a long time have?
> Seems likely to me that short term memories lack that.

Another very good question. We don't know yet, but it seems to involve
restructuring of the cell, the branching of new synapses and
production of new proteins.

> 2- Do cells detach and reattach to others?

It is likely in the brain, and definitely occurs in some other tissues
(fibroblasts are the most notable).

> 3- Is there an intermediate phase between approach and connection
> in which signals may be passed?

Maybe. There are neurotrophic factors that drift around, the diffuse
volume conduction of some chemicals which may or may not be useful,
and the retogerade messengers like nitrogen oxide which I don't really
understand. I think there is a complex chemical dialogue going on
around every neuron.

> 4- On average, what direction do axons point?

Depends on where you are. In the brain, most seem to project either up
or down to the thalamus, and locally perpendicular to the cerebral
folds and ridges, or connect remote cortical areas with long, c-shaped
bundles. But this is different in different parts of the brain. Some
form diffuse networks, others move straight to their destinations.

> What happens during adaptation?

A lot, I simply cannot give you a short answer. Try looking at Kandel
et al, the memory chapter has IMHO an excellent overview.

> 1- What is "neural noise"?
> Is that why my ears squeal?

Sometimes. Usually it is the death cry of a single auditory
neuron. Some neurons just fire spikes at random or due to random
excitations in their environment.

> >> >I need a funtional brain map
> >> >to see what tasks are next to eachother;
> >> >I've spent several hours looking but failed.
> >
> >We don't know where and how "Tasks" are stored, although we have
> >reasonably good maps of some functions (like the visual cortex,
> >primary motor system, speech etc).
> Please,
> some good technical terms for brain map,
> that's all I need.

I have started to look for it, I'll keep you posted.

Anders Sandberg                                      Towards Ascension!                  
GCS/M/S/O d++ -p+ c++++ !l u+ e++ m++ s+/+ n--- h+/* f+ g+ w++ t+ r+ !y