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The hippocampus is =not= a 'spatial' map

John H. johnh at faraway.hgmp.mrc.ac.uk
Thu Jan 22 23:33:08 EST 2004

The below is a paper I browsed last night and found quite interesting. The
author argues that the hippocampus acts as a type of monitor of various body
states and supports his argument by references to a great many receptors and
ligands found in the hippocampus. He makes the interesting observation that
the famous HM not only had no long term memory, but rarely reported feeling
hungry, tired etc and was pain tolerant. Thus, to use Ken's terminology, the
hippo acts as a super configuration system.

John H.

Journal of Endocrinology (2001) 169, 205-231
0022-0795/01/0169-205  2001 Society for Endocrinology Printed in Great
Hormones and the hippocampus
R Lathe
Centre for Genome Research and Centre for Neuroscience, University of
Edinburgh, West Mains Road, Edinburgh EH9 3JQ, UK
(Requests for offprints should be addressed to R Lathe, Centre for Genome
Research, King's Buildings, West Mains Road, Edinburgh EH9 3JQ, UK;
Email: rlathe at ed.ac.uk)
Hippocampal lesions produce memory deficits, but the
exact function of the hippocampus remains obscure.
Evidence is presented that its role in memory may be
ancillary to physiological regulation. Molecular studies
demonstrate that the hippocampus is a primary target for
ligands that reflect body physiology, including ion balance
and blood pressure, immunity, pain, reproductive status,
satiety and stress. Hippocampal receptors are functional,
probably accessible to their ligands, and mediate physiological
and cognitive changes. This argues that an early
role of the hippocampus may have been in sensing soluble
molecules (termed here 'enteroception') in blood and
cerebrospinal fluid, perhaps reflecting a common evolutionary
origin with the olfactory system ('exteroception').
Functionally, hippocampal enteroception may reflect feedback
control; evidence is reviewed that the hippocampus
modulates body physiology, including the activity of the
hypothalamus-pituitary-adrenal axis, blood pressure,
immunity, and reproductive function. It is suggested that
the hippocampus operates, in parallel with the amygdala,
to modulate body physiology in response to cognitive
stimuli. Hippocampal outputs are predominantly inhibitory
on downstream neuroendocrine activity; increased
synaptic efficacy in the hippocampus (e.g. long-term
potentiation) could facilitate throughput inhibition. This
may have implications for the role of the hippocampus and
long-term potentiation in memory.
Journal of Endocrinology (2001) 169, 205-231
"Matthew Kirkcaldie" <Matthew.Kirkcaldie at removethis.newcastle.edu.au> wrote
in message
news:Matthew.Kirkcaldie-1A9237.13551422012004 at seagoon.newcastle.edu.au...
> You know, Ken, I waded through the jargon of your post and from what I
> could make of it, it sounds like a reasonable account of what the
> hippocampus may be doing.  However you are going to limit your
> interaction with other interested people if you stick to such obscure
> and undefined terminology - it becomes such an effort to read that there
> is little motivation to do so.  It's a pity, since there seem to be some
> sound ideas buried within.  I would guess that this is the reason you
> have had little success with publication.
> As a rule, I always avoid defining new terms, preferring to limit my
> explanations to those achievable using English and widely-understood
> anatomical / physiological terms.  Often it can be a good discipline.
>       MK.

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