On Tue, 27 Feb 2001, Jeffrey Nagelbush went:
> The following quote is from the Feb. 23 issue of Science: "Anatomical and
> physiological studies have shown that three structures of the limbic
> system-the prefrontal cortex, the amygdala, and the nucleus acumbens-are
> connected and speak to one another."
>
> My question is, when did the prefrontal cortex become part of the limbic
> system? Is this common usage today?
"Prefrontal cortex" and "limbic system" are cans of semantic worms.
Here's a few notes on each of them from Terence R. Anthoney's
_Neuroanatomy and the Neurologic Exam: A Thesaurus of Synonyms,
Non-Synonyms, and Terms of Variable Meaning_.
On "prefrontal cortex":
"As used in the word `prefrontal,' the prefix `pre-' means `anterior
part of,' *not* `anterior to'...
"The prefrontal cortex is primarily an area of nonspecific frontal
association cortex which remains after excluding `functional areas'
of the frontal lobe, such as the primary motor area and the premotor
area. The amount of cortex assigned to the prefrontal area by
authors of the 25 recent textbooks of neuroscience varies
greatly....
"Even though much of the orbital [bottom] surface of the frontal
lobe lies far anterior [...], some authors *exclude* the orbitofrontal
cortex from their prefrontal area....[T]his exclusion results from
data strongly linking the orbitofrontal cortex anatomically with the
so-called limbic system."
On "limbic system":
"Other *non*pathway structures included quite frequently in the
limbic system are parts of the neocortex, of the brain stem, and of
the olfactory system. The areas of neocortex involved seem to be
divided into two overlapping regions--the cortex in the orbital area
of the frontal lobe, in the temporal polar area, and/or in the
insula (8 texts) and the prefrontal cortex (2 texts). [Note: the
insula is anatomically continuous with orbitofrontal cortex. --David]
So the answer--as is so often the case in neuroanatomy--is that it
depends which book you read. However, if "prefrontal cortex" is
defined to exclude orbitofrontal cortex, then calling it "limbic"
would probably put one in the minority.
--David Epstein
[EMAIL PROTECTED]
