Richard Hall wrote in message ...
>So, basically, the brain minimizes neural circuits controlling
>behaviors as it becomes more efficient. I work on crustacean central
>pattern generators that are anatomically defined and have limited,
>but significant, capacity to adapt. No problem.
>>However, the process of learning or inventing controls requires
>involvement of many more circuits. In the non-learning brain, there
>may be a minimal level of neural activity necessary for specific
>activities. Indeed, cell death and synaptic pruning, are mechanisms
>that may account for those refinements. Free ranging animals need
>to constantly learn and adapt, especially if we are discussing
>primates which are characterized by extraordinary learning
>capacities. The reality seems to be that discovery and learning
>processes have an absolute need for far more neural activity. Thus
>while moment to moment we use only x percent of our brain, we need
>all of our brain with all of its redundancies and parallel circuits
>to function as learning and adaptive animals.
This reminds of Steven Rose's account in "The Making of Memory" of training
the chicks to peck the right coloured ball. Learning the activity generated
a lot of activity in one hemi for a number of hours then it transferred to
the homotopic opposite (IMHV region I believe Rose called it). What
surprised Rose was the sheer amount of neural activity to learn such a
simple task, a phenomenon that made him question whether or not the
experimental setting was playing an unknown part.
I've heard of similiar in humans, widespread cortical activity reduces to a
relevant region, and with motor skills at least, once learned, this function
appears to be largely facilitated through the cerebellum. Prior to this,
well you know, visual, motor, premotor. All that "redundant" stuff is for
learning; although I find it conceivable that with age and practice less of
that stuff is required.
John
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>>Thus, we use all of our brain.
>>rlh
>>>On 16 Jul 1999 13:57:37 GMT, didier at Glue.umd.edu (Didier A. Depireux)
>>wrote:
>>>> >Richard Hall (rhall at uvi.edu) wrote:
>> >: This is getting nowhere, slowly and painfully.
>> >: If one assumes that natural selection acts on phenotypes resulting in
>> >: improved fitness, it seems reasonable to assume that anything not
>> >: contributing to fitness would be eliminated.
>> >
>> >I think that part of the idea that we need only 10 % blahblahblah, is
that
>> >at some point you might need 100%, while you are developing and making
>> >connections, but once all the circuitry is established and you just
cruise
>> >through life, you only need 10% of what is there.
>> >
>>snipped
>> >
>> > Didier
>>>>Precisely. The is much research that show that when learning a new
>>task all areas of our brains become involved, even those not normally
>>associated with the actions required as the brain consciously sets
>>about learning the actions required. At these times the brain does
>>not behave like a collection of isolated pathways, each doing their
>>own thing as is normally the case, but rather as a coherent system.
>>>>Then as we begin to get a handle on the task the number of brain
>>regions involved diminishes until only the bare necessities required
>>'light up" when the task is performed. Effectively, the brain
>>establishes a "template" or "habit" that can produce the same
>>behaviour as if it were still going through all the hoops of being
>>consciously aware, but in reality no 'conscious" input is involved.
>>>>These might be of interest in this regard:
>>>>"The neural correlates of consciousness: an analysis of cognitive
>>skill learning"
>>. Raichie Marcus E, Philosophical Transactions of the
>>Royal Society London B, vol 353, p 1889 (1998)
>>>>"The basal ganglia and chunking of action
>>repertoires"
>>Graybiel Ann M., Neurobiology of
>>Learning and Memory, vol 70, p 119 (1998)
>>>>"The time course of changes during motor
>>sequence learning: a whole-brain fMRI study"
>>Toni Ivan et al, Neurolmage, vol 8, p 50(1998)
>>>>>>Ian
>
