function of hippocampus

[Ken Miller]

With respect to recent postings about models of hippocampus and
memory, I'd like to toss in a cautionary note.  A recent report
(Elisabeth A. Murray and Mortimer Mishkin, "Object Recognition and
Location Memory in Monkeys with Excitotoxic Lesions of the Amygdala
and Hippocampus", J. Neuroscience, August 15, 1998, 18(16):6568-6582)
finds no deficit in tasks involving visual recognition memory or
spatial memory with lesions of hippocampus and amygdala.  Instead,
deficits in both cases are associated with, and only with, lesion of
the overlying rhinal cortex.  They mention in the discussion evidence
that "has suggested that the hippocampus may be more important for
path integration on the basis of self-motion cues than for location
memory, per se" (though Redish' recent posting mentions evidence
against this from recent experiments of Alyan and McNaughton; I
couldn't find a reference in medline).  This is the latest in a series
of reports along these lines from the Mishkin lab, who did much of the
original lesion work that seemed to implicate hippocampus in memory.

I'm not in any way an expert on this literature -- only a very distant
observer -- but I worry that, based on lesion studies that also
involved lesions of overlying cortex, both the neuroscience and
connectionists communities may have jumped to a wrong conclusion that
the hippocampus has a special role in episodic and/or spatial memory.
I'd be interested to know if there's still good reason to believe in
such a role ...

Ken
 
        Kenneth D. Miller               telephone: (415) 476-8217
        Dept. of Physiology		fax: (415) 476-4929
        UCSF                            internet: ken at phy.ucsf.edu
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