Scientists 'locate' intelligence

Sergio Navega snavega at attglobal.net
Mon Aug 21 06:59:29 EST 2000


mejqb at my-deja.com wrote in message <8nmnvd$eag$1 at nnrp1.deja.com>...
>In article <39885cd9_4 at news3.prserv.net>,
>  "Sergio Navega" <snavega at attglobal.net> wrote:
>> MS wrote in message ...
>> >It sounds like a premature generalization to say that because several
>tasks
>> >activated one area that it validates a g-factor of intelligence.
>Given the
>> >role of working memory across complex tasks and the importance of
>> >dorsolateral PFC in working memory, couldn't a working memory
>impairment
>> >account for those findings?
>> >
>> >--
>> >Marcello
>> >
>>
>> I agree. Although I'm sympathetic to the concept of general
>intelligence,
>> I don't think we have a specific area of the brain responsible for
>> it. I think it is premature and somewhat "sensationalistic" to claim
>> to have found such an area.
>
>The notion of a specific area of activity and the notion of a general
>intelligence factor as propounded in The Bell Curve aren't even
>vaguely related.

I'm not sure why you bring The Bell curve to the discussion, as it
offers something that's far from what has been discussed here.

>After all, the fact that thinking takes place in a
>specific organ, the brain, does not support the claim of a "general
>intelligence factor", so no more specific location of activity does
>either.  The g-factor has to do with correlation of *abilities*, not
>*locations*.

Agreed, this is pretty much what I said earlier.

>
>What's fascinating is how few people who are interested in the subject
>of intelligence and are aware that there are variations intelligence
>ever imagine that they might be lacking in some aspect of
>intelligence, and in fact are insulted by the suggestion, despite it
>being an empirical matter.
>

What's fascinating for me is the endurance of dogmas which insist
in avoiding thinking about good points of other conflicting arguments.
One could say that the brain is not a blank slate, but that does
not imply it is a domain specific agglutination of "mental organs".

>> One of the things we should have in mind
>> when thinking about brains is that few things are really
>"concentrated".
>> Evolution is merciless with everything that is too specific, and
>> human brains evolved exactly to be adaptive and generic. Plasticity
>> is the rule.
>
>Well, you might have been able to say that a decade ago when the brain
>was still thought of as an amorphous blob, but since then a great deal
>has been learned about the detailed localized structure of the brain
>and localized function.  But as usual, the beliefs of individuals lags
>behind the state of accumulated human knowledge.
>

You might have said that 5 years ago, but not today. Although the
idea of brains as general purpose "computers" without any
specialization is long gone, so is the idea that it is a
pre-specified organ, with "compartments" genetically specialized
in the processing of specific stimuli. Take vision, for instance.
One could take the visual cortex to be an example of a specific area
of genetically specified origin, unable to process nothing more
but visual stimuli. This is not the case.

There's a huge amount of research indicating that the
visual cortex is reused in blind humans to help processing of
somatosensory and auditory cortexes. Cortical columns *change*
in structure because of that, approaching the organization
found in auditory cortex.

Deaf individuals were seen (by fMRI) activating the auditory
cortex in response to visual stimuli related to american sign
language. Only a plastic brain could manage to get that.

Some say about special areas of the brain responsible for the
identification of faces. Yes, there are these areas, the question
is where they come from? From specific genetic instructions or
from self-organization? Recent studies showed that this same area
is used not only for faces, but also for the recognition of
sophisticated visual stimuli by experts (experts in cars, for
instance, also use this area).

So what is being discovered is that brains are not general purpose
organs, but neither fully determined. They are complex systems,
built from general genetic guidances but strongly subject to
the self-organizing effect of impinging stimuli.

Regards,
Sergio Navega.











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