NEUROANATOMY: Backwardness of human neuroanatomy

[Alan J. Robinson]

On Mon, 6 Nov 1995 20:57:10 -0500, 
Jim Kohl  <jkohl at vegas.infi.net > wrote:

>The mammalian gonadotropin-releasing hormone (GnRH) neuronal system also 
>seems to be fairly well mapped. It's linkage to olfaction is of interest 
>to me because of the olfactory-neuroendocrine-behavioral model (social 
>environmental chemical stimuli (pheromones) appear to activate genes in 
>GnRH neurosecretory neurons, which influences GnRH pulsatility, 
>luteinizing hormone/follicle stimulating hormone ratios, steroidogenesis, 
>and thus behavior. 
>
>Anyway, is there someone who can help me locate a good source that 
>details the location of GnRH neurons in primates as well as which of the 
>structures in which they are found can be considered part of the limbic 
>system? The location of GnRH receptors would also be a plus in my 
>literature review geared towards integrating facets of human chemical 
>communication with a psychoneuroendocrine model of behavioral 
>development.
>

Jim:

I'm not familiar in detail with the GnRH system, but I have a couple of
general comments re brain functional neuroanatomy.  I've read on several
occasions about the Human Brain Project, which appears to be a pet 
project of Floyd Bloom, who is now Editor-In-Chief of Science.  The 
idea is to collect all this type of information and make it available 
in computer graphic form for viewing by neuroscientists.  I believe 
that NIMH is the home for the Project, but I have no information as 
to its current status.

A complicating factor in brain functional anatomy is that functions do 
not appear to be rigidly tied to locations - a function can be 
distributed over many structures, and even the locations themselves 
can change as a result of central or peripheral neural damage.  There 
may not even be exact correspondence between different animals of the 
same species.

A couple of classic examples - even though the hypothalamus is one of 
the most critical organs of the body, an animal can largely survive 
its slow destruction over a period of several weeks; and the rage 
response in the cat can be triggered at three different sites - the 
amygdala, the hypothalamus, and the periaqueductal grey.  Because the 
hypothalamic site was the first discovered, it lead to the erroneous 
conclusion that the hypothalamus was the seat of emotions in the body, 
an error which is still sometimes repeated in the literature 
today.                       

This whole area of the brain and its functioning is obviously of the 
utmost importance for its integration of all the different 
physiological homoestatic, brain state, and emotional aspects of 
animal behavior.  Some aspects appear to be better understood than 
others - there still appear to be major gaps in the brain-immune 
system connection.  The hypothalamic neural location for the 
sympathetic "fight or flight" reaction was announced this week in 
Science, even though it has been known about since the early part of 
this century.  And the molecular action of how glucocorticoids 
suppress the immune system was only announced the previous week in 
Science.

PS: the author of the Gonadotropins article in the Encyclopedia of 
Neuroscience is Charles H. Sawyer of UCLA.  You should be able to 
locate a comprehensive review article in the literature using Medline.

AJR