X-Message-Number: 12451
Date: Wed, 22 Sep 1999 19:47:43 -0400
From: Jan Coetzee <>
Subject: Pulling the plug on the hippocampus

Pulling the plug on the hippocampus


              The hippocampus is intimately involved in the formation of
memories. But
                details of its involvement are difficult to ascertain.
The complexity of memory
                is one reason. Memories require mechanisms for encoding,
storage,
                consolidation, and retrieval. It would be very useful to
have some way of
                turning the hippocampus on and off at will during a
memory test. That is now
                possible with the development of a novel technique that
uses a drug to block
                glutamate receptors in the hippocampus. Early
application of the approach
                indicates that the hippocampus plays a key role in the
encoding and retrieval of
                spatial memory.






           Nature Neuroscience
              October 1999 Volume 2 Number 10 pp 898 - 905



              Reversible neural
              inactivation reveals
              hippocampal participation
              in several memory
              processes


                  G. Riedel1, 2, 6, J. Micheau3, 6,
                  A.G.M. Lam4, E.v.L. Roloff1, 2, S.J.
                  Martin1, H. Bridge1, 5, L. de Hoz1,
                  B. Poeschel1, J. McCulloch4 &
                  R.G.M. Morris1

                  1. Department and Centre for Neuroscience,
                  University of Edinburgh Medical School,
                  Crichton Street, Edinburgh EH8 9LE, UK
                  2. Department of Biomedical Sciences,
                  University of Aberdeen, Aberdeen AB25 2ZD,
                  UK
                  3. Laboratoire de Neurosciences
                  Comportementales et Cognitives, CNRS UMR
                  5807, Universit  de Bordeaux I, Avenue des
                  Facult s, 33405 Talence Cedex, France
                  4. Department of Neuroscience, Wellcome
                  Surgical Institute, University of Glasgow,
                  Garscube Estate, Glasgow G61 1QH, UK
                  5. Present address: Department of
                  Experimental Psychology, University of
                  Oxford, Oxford OX1 3UD, UK
                  6. The first two authors contributed equally
                  to this work.
                  Correspondence should be addressed to
                  R G M Morris. e-mail: 


              Studies of patients and animals with
              brain lesions have implicated the
              hippocampal formation in spatial,
              declarative/relational and episodic
              types of memory. These and other
              types of memory consist of a series of
              interdependent but potentially
              dissociable memory
              processes encoding, storage,
              consolidation and retrieval. To identify
              whether hippocampal activity
              contributes to these processes
              independently, we used a novel method
              of inactivating synaptic transmission
              using a water-soluble antagonist of
              AMPA/kainate glutamate receptors.
              Once calibrated using
              electrophysiological and
              two-deoxyglucose techniques in vivo,
              drug or vehicle was infused chronically
              or acutely into the dorsal hippocampus
              of rats at appropriate times during or
              after training in a water maze. Our
              findings indicate that hippocampal
              neural activity is necessary for both
              encoding and retrieval of spatial
              memory and for either trace
              consolidation or long-term storage.

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