Brain usage....male and female????

F. Frank LeFever flefever at ix.netcom.com
Sat Jul 17 10:54:51 EST 1999



Just one small aside, triggered by  reference to estimates of energy
consumption (far, far, below): recent study (in Proc Nat Acad Sci? 
possibly Nature??) suggests that RELATIVE changes in metabolic rate may
be misleading as indices of cognitive or sensory activitation;
increases are to a certain critical level, most obvious if basal state
is low (e.g. in anaesthesia), perhaps difficult to detect if activity
already near that level.

F. Frank LeFever, Ph.D.
New York Neuroopsychology Group


In <v04210107b3b4f1bf8933@[132.236.112.58]> rhall at uvi.edu (Richard
Hall) writes: 
>
>Cruise through life...are you a tenured full professor with a funded
chair? ;-)
>
>Programmed cell death is part of life and it is not surprising that 
>neurons and synaptic connections change throughout a life span.  Lets 
>play a numbers game.
>
>If at age 15 one typically uses a fixed percentage of neurones 
>(organized in circuits), it stands to reason that as cells die, some 
>of the redundant circuits are lost.  If there is a finite number of 
>circuits needed for a function, the percentage of neurones would 
>conceivably increase (15 of 92 versus 15 of 100.)  Hence, I use a 
>greater percentage of my ebbing brain capacity today than yesterday. 
>Coincidently, I have fewer nephrons, islet cells, patent capillary 
>beds, and muscle fibers.  When I am in my dottering 90's I will 
>likely be using everything and anything I can to waddle to the head, 
>to the table, and to my computer screen where I will suck lemon drops 
>to provoke my three remaining salivary glands to moisten my dried old 
>mouth.  100% efficiency may not be all it is cracked up to be, but 
>I'm not giving up until I get it perfect, even if it takes me another 
>100 years.
>
>We use all of our brain cells in a somewhat orderly fashion, from time
to time.
>
>  A PET scan can be used to monitor metabolic activity of neurones in 
>the brain.  Cells in use expend more energy than cells at rest.  The 
>distinctive patterns of activity associated with specific tasks 
>demonstrate the involvement of untold neurons, many of which are not 
>active most of the time.   An area that is consistently inactive 
>typically reflects a pathology.   But virtually every neuron in the 
>brain remains metabolically active and functional, unless it becomes 
>isolated, impoverished of nutrients and synaptic inputs.
>
>Our conscious levels and intellectual capacities vary from time to
time.
>
>Clearly our brain has a range of calculating "gears".  Most of us 
>experience heightened awareness and intellectual prowess following 
>modest stimulation by caffeine.  Abuse of amphetamines is associated 
>with accelerated powers of calculation that eventually overload and 
>precipitate a deep and profound depression. The immense emotional 
>"kick" that results from the ability to think underpressure  reflects 
>the adaptive capacity of our brains from moment to moment.
>
>In calculating basal metabolic rates, it is generally assumed that 
>ion pumps consume about 600 Kcal per day.  Every neuron in the body 
>needs pumps to maintain ionic asymmetries.  It would be a waste to 
>spend all that energy on cells that are not needed.  We use every 
>cell in our body, we use every neuron, but not all at the same time...
>
>Men vs Women ;-)
>
> From a developmental perspective, female is the default course of 
>human development (turtles too.)   Males lack the genetic information 
>needed to be female.   It astounds me that women keep harping about 
>our loutish ways...we are the victims of evolution.  Males are the 
>victim of thousands of generations of mate selection- women do choose 
>their mates- that we have arrived at this sorry state.  We have 0.5% 
>less genetic information at our disposal (Y versus X chromosomes.)
>
>Now 0.5% does not seem like much, but it happens to be a very 
>important 0.5%.   The gene for dropping the toilet seat is X linked. 
>We need to be bigger because we need the additional mass because 
>redundancy does not win arguments.   We are so inefficient, we need 
>larger salaries to get by.  Have you priced 15 inch high profile 
>radials lately?  Whew!  Men buy pickups because the smaller passenger 
>area means fewer folks to entertain or keep track of.  Women are 
>smarter and have raised male anxieties to the uptight point where we 
>whistle when we pass air.
>
>enjoy your weekend.
>
>rlh
>
>
>
>>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. Consider the
>>scientifically established fact that the majority of your connections
and
>>even neurons disappear between fetal stage and teenage years.
>>
>>						Didier
>>
>>--
>>Didier A Depireux                              didier at isr.umd.edu
>>Neural Systems Lab                 http://www.isr.umd.edu/~didier
>>Institute for Systems Research          Phone: 301-405-6557 (off)
>>University of Maryland                                -6596 (lab)
>>College Park MD 20742 USA                     Fax: 1-301-314-9920
>




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