Intrinsic connections in tree shrew V1
imply a global to local mapping

Vision Research, Volume 44, Issue 9, Pages 857-876, April 2004
Doi: 10.1016/j.visres.2003.11.009
David M. Alexandera,f, Paul D. Bourkeb, Phil Sheridanc,
Otto Konstandatosd, James J. Wrighte,f.

a Brain Dynamics Centre, Acacia House, Westmead Hospital, Hawkesbury Road, Westmead 2145, Sydney, Australia
b Centre for Astrophysics and Supercomputing, Swinburne University of Technology, 523 Burwood Road, Hawthorn 3122, Melbourne, Australia
c School of Computing and Information Technology, Griffith University, University Drive, Meadowbrook 4131, Brisbane, Australia
d School of Mathematics and Statistics, University of Sydney, City Road, Glebe 2006, Sydney, Australia
e The Liggins Institute, University of Auckland, 2-6 Park Avenue, Grafton 1001, Auckland, New Zealand
f Brain Dynamics Laboratory, Mental Health Research Institute ofVictoria, 155 Oak Street, Parkville 3052, Melbourne, Australia


The local-global map hypothesis states that locally organized response properties --- such as orientation preference --- result from visuotopically organized local maps of non-retinotopic response properties. In the tree shrew, the lateral extent of horizontal patchy connections is as much as 80-100% of V1 and is consistent with the length summation property. We argue that neural signals can be transmitted across the entire extent of V1 and this allows the formation of maps at the local scale that are visuotopically organized. We describe mechanisms relevant to the formation of local maps and report modelling results showing the same patterns of horizontal connectivity, and relationships to orientation preference, seen in vivo. The structure of the connectivity that emerges in the simulations reveals a "hub and spoke" organization. Singularities form the centers of local maps, and linear zones and saddle-points arise as smooth border transitions between maps. These findings are used to present the case for the local-global map hypothesis for tree shrew V1.