From owner-biophys@hgmp.mrc.ac.uk Tue Sep 5 11:22:12 2000 Return-Path: Received: by mercury.hgmp.mrc.ac.uk (Postfix, from userid 110) id 2DF2017AD4; Tue, 5 Sep 2000 11:22:12 +0100 (BST) Received: by mercury.hgmp.mrc.ac.uk (Postfix, from userid 6024) id 906C217AD3; Tue, 5 Sep 2000 11:22:10 +0100 (BST) Received: from niobium.hgmp.mrc.ac.uk (niobium [193.62.192.41]) by mercury.hgmp.mrc.ac.uk (Postfix) with ESMTP id E6AA9415CF for ; Tue, 5 Sep 2000 11:22:09 +0100 (BST) Received: (from news@localhost) by niobium.hgmp.mrc.ac.uk (8.9.3+Sun/8.8.8) id LAA01601 for biophys-list@hgmp.mrc.ac.uk; Tue, 5 Sep 2000 11:22:09 +0100 (BST) X-Authentication-Warning: niobium.hgmp.mrc.ac.uk: news set sender to using -f From: A.van.Ooyen@nih.knaw.nl (Arjen van Ooyen) X-Newsgroups: bionet.biophysics Subject: Axonal Competition Date: 5 Sep 2000 11:22:07 +0100 Organization: Netherlands Institute for Brain Research Lines: 61 Message-ID: <39B4C948.DCBBBCE6@nih.knaw.nl> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit X-Trace: niobium.hgmp.mrc.ac.uk 968149328 1599 193.62.192.80 (5 Sep 2000 10:22:08 GMT) X-Complaints-To: news@net.bio.net X-Received: by mercury.hgmp.mrc.ac.uk (Postfix, from userid 6024) id 8915A17AD3; Tue, 5 Sep 2000 11:22:06 +0100 (BST) X-Received: from ns1.ioi.knaw.nl (ns1.ioi.knaw.nl [194.171.152.2]) by mercury.hgmp.mrc.ac.uk (Postfix) with ESMTP id 7E7CF415D5 for ; Tue, 5 Sep 2000 11:22:04 +0100 (BST) X-Received: from nibr.nih.knaw.nl (nibr.nih.knaw.nl [192.87.10.129]) by ns1.ioi.knaw.nl (8.9.3/8.9.3) with ESMTP id MAA18936 for ; Tue, 5 Sep 2000 12:22:02 +0200 (MET DST) X-Received: from nih.knaw.nl (nibr.nih.knaw.nl [192.87.10.129]) by nibr.nih.knaw.nl with ESMTP (8.8.6 (PHNE_14041)/8.7.1) id MAA17517 for ; Tue, 5 Sep 2000 12:22:01 +0200 (METDST) X-Mailer: Mozilla 4.7 [en] (X11; I; HP-UX B.10.20 9000/816) X-Accept-Language: en X-To: biophys@net.bio.net To: biophys@hgmp.mrc.ac.uk Sender: owner-biophys@hgmp.mrc.ac.uk Precedence: bulk New Paper: Development of Nerve Connections under the Control of Neurotrophic Factors: Parallels with Consumer-Resource Systems in Population Biology. Arjen van Ooyen & David J. Willshaw, J. Theor. Biol. (2000) 206: 195-210. Download in gzipped PostScript format or PDF format from: http://www.anc.ed.ac.uk/~arjen/competition.html or request reprint: A.van.Ooyen@nih.knaw.nl Abstract -------- We show that a recently formulated model of axonal competition can be rewritten as a general consumer-resource system. This allows neurobiological phenomena to be interpreted in population biological terms and, conversely, results from population biology (where competition is better understood) to be applied to neurobiology. Using findings from population biology, we study two extensions of our axonal competition model. In the first extension, the spatial dimension of the target is explicitly taken into account. We show that distance between axons on their target mitigates competition and permits the coexistence of axons. The model can account for the fact that, in many types of neurons, a positive correlation exists between the size of the dendritic tree and the number of innervating axons surviving into adulthood. In the second extension, axons are allowed to respond to more than one neurotrophic factor. We show that this permits competitive exclusion within one type of axons, while at the same time there is coexistence with a different type of axons innervating the same target. The model offers an explanation for the innervation pattern found on cerebellar Purkinje cells, where climbing fibres compete with each other until only a single one remains, which coexists with parallel fibre input to the same Purkinje cell. -- Arjen van Ooyen, Netherlands Institute for Brain Research, Meibergdreef 33, 1105 AZ Amsterdam, The Netherlands. email: A.van.Ooyen@nih.knaw.nl website: http://www.anc.ed.ac.uk/~arjen phone: +31.20.5665483 fax: +31.20.6961006 --- .