"Working memory" is a very nebulous concept, and for it to have any
useful meaning, it needs to be rigorously defined. I imagine that 20/20
didn't try to define working memory. As for HM, as I remember, his
short-term memory was intact as defined by digit span. But if he
wasn't allowed to rehearse information, he forgot it very quickly, much
more quickly than neurologically-healthy people would. So I think it's
accurate to say that HM had a "working memory" deficit, related to
his hippocampal damage.
I know of some evidence for a hippocampal role in working memory
in the human event-related brain potential (ERP) literature. Intra-
cranial recordings from several labs (McCarthy, Halgren, and others)
has shown that an ERP similar to the scalp-recorded P300 component
is generated in the hippocampus. The P300 is thought to be related
to a "context-updating" function involved in working memory. A
hippocampal analog of a similar component, the "novelty P3", has
also been found. And in addition, Knight has found that people with
damage to the posterior hippocampus don't have scalp-recorded
novelty P3s.
Kevin
-----------------------------------------------------------
Kevin Spencer
Cognitive Psychophysiology Laboratory
Dept. of Psychology and Beckman Institute
University of Illinois at Urbana-Champaign
kspencer at s.psych.uiuc.edu
-----------------------------------------------------------
Jeremy Leipzig <jeremyl at mindspring.com> wrote in article
<34CB97D8.41E8143A at mindspring.com>...
> A few weeks ago there was a spot on 20/20 which discussed the
> effects of aging on working memory. The experts they interviewed were
> claiming that a progressive degeneration of the hippocampus was
> responsible for declines in working memory.
> I've always understood that the hippocampus was only involved in
> consolidation - or transfer into long term memory. My undergrad
> neuroscience textbook also states that the ubiquitous ex-hippocampal
> patient H.M.'s short-term memory was "intact." H.M. suffered from
> anterograde amnesia, specifically in declarative memory.
> What are your thoughts on this matter?
> --
> Jeremy Leipzig http://www.mindspring.com/~jeremyl> (919)469-0936
> 1204 Kilmory Dr. Cary, NC 27511
>jeremyl at mindspring.com>>>