[sci.bio] Men and women

palosaari@oxy.edu (Jedidiah Jon Palosaari) (10/21/89)

I heard somewhere that scientists have found in recent studies that there
is a difference in the brain structure of men and women, in that women
have a major connection between the right and left halves of the brain,
whereas men do not.  I was also told that this means that women can use both
sides of their brain at the same time, whereas men have difficulty doing
that and can only concentrate on logic *or* emotions separately.  Men
who do have this connection in the brain have dyslexia.
     Does anyone know of the validity of this connection, and its probable
effects on thought patterns?

dmark@acsu.Buffalo.EDU (David Mark) (10/22/89)

In article <55243@tiger.oxy.edu> palosaari@oxy.edu (Jedidiah Jon Palosaari) writes:
>I heard somewhere that scientists have found in recent studies that there
>is a difference in the brain structure of men and women, in that women
>have a major connection between the right and left halves of the brain,
>whereas men do not.  I was also told that this means that women can use both
>sides of their brain at the same time, whereas men have difficulty doing
>that and can only concentrate on logic *or* emotions separately.  Men
>who do have this connection in the brain have dyslexia.
>     Does anyone know of the validity of this connection, and its probable
>effects on thought patterns?

A fairly-recent book by Diane Halpern has some interesting information related
to this topic:

Halpern, Diane F., 1986.  Sex Differences in Cognitive Abilities.  Hillsdale,
  NJ:  Lawrence Erlbaum Associates, Inc.

This book seems to do a very nice job of summarizing a wide variety of
results on differences in mental performance of various sorts of tasks and
activities that exist between male and female humans.  One very 
consistent difference is that males tend to perform better on "spatial"
tasks, and females to perform better on "verbal" tasks.  Halpern then
observes that there is also a persistent interaction effect with
handedness:  left-handed individuals "tend" to have spatial and verbal
abilities that are somewhat more like those of the other sex.  That is,
left-handed males tend to perform better on verbal and less well on spatial
tasks than do right-handed males, etc.  Halpern takes this to be strong
circumstantial evidence that there is a biological (brain function
differentiation) basis for the cognitive differences.  She also notes a lot
of sex differences in cognitive abilities that are almost certainly
attributable to "environmental" or "nurture" factors, differences in the
ways male and female children are treated, etc.

I recall hearing about 10 years ago about males having higher hemispheric
differentiation of brain functions, and of males tending to be better than
females on "single-minded" tasks, females better at performing integrative
tasks.  That's why so many of our top managers and politicians are
female.   :-)

I also recall hearing recently that the brain-function hemisperic different-
iation can now be studies using real-time monitoring of temperature in the 
brain.  You can give someone a mental task and see what parts of the brain
are activiated to solve the task.  And I recall (with less confidence) that
this was confirming the sex differences in brain function localization.

David Mark
Center for Cognitive Science
SUNY at Buffalo

dmark@cs.buffalo.edu

werner@aecom.yu.edu (Craig Werner) (10/23/89)

In article <55243@tiger.oxy.edu>, palosaari@oxy.edu (Jedidiah Jon Palosaari) writes:
> I heard somewhere that scientists have found in recent studies that there
> is a difference in the brain structure of men and women, in that women
> have a major connection between the right and left halves of the brain,
> whereas men do not.  I was also told that this means that women can use both
> sides of their brain at the same time, whereas men have difficulty doing
> that 

	It ain't that simple.  The connection is the Corpus callosum.
Both men and women have it.  However, as a percentage of brain mass it is
bigger in women than in men.  Actually, in absolute terms it is almost
the same size, but you 	have to take into account that on the average men's
brains are larger than women's, mostly because on the average men's
bodies are larger than women's and there is a roughly proportional
relationship.  It is not clear whether this represents any functional
difference.
	There is also a nucleus in the hypothalamus which is much larger
in males than in females in a variety of mammalian species. Since the
name of this nuclei betrays only this fact, and nothing about function,
I'm not sure you can make any judgments on the SDN (Sexually Dimorphic
Nucleus) of the hypothalamus, unless somebody knows something about it
that's more recent than about three years old. (Three years ago, the fact
that it really existed was big news, and that's the last I heard of it.)

-- 
	        Craig Werner   (future MD/PhD, 4.5 years down, 2.5 to go)
	     werner@aecom.YU.EDU -- Albert Einstein College of Medicine
              (1935-14E Eastchester Rd., Bronx NY 10461, 212-931-2517)
                         "I wouldn't have invited me either."