Paper available: reverse suture and orientation map development

[Ken Miller]

The following paper is now available from 
ftp://ftp.keck.ucsf.edu/pub/ken/miller-erwin01.ps (postscript, 4 MB)
or
ftp://ftp.keck.ucsf.edu/pub/ken/miller-erwin01.ps.gz (gzipped ps, 1.2 MB)
or from 
http://www.keck.ucsf.edu/~ken (click on 'publications', then on
                               'models of neural development')

"Effects of Monocular Deprivation and Reverse Suture On Orientation
Maps Can Be Explained By Activity-Instructed Development of
Geniculocortical Connections"
		 by K.D. Miller and E. Erwin
This is a final draft of a paper that has now appeared as
Visual Neuroscience 18:821-834 (2001).

Abstract:

Mature visual cortex shows a single, binocularly matched orientation
map.  This matching develops without visual experience.  It persists
despite early monocular deprivation that largely eliminates one eye's
map, followed by reverse suture (deprivation of the previously open
eye and opening of the previously deprived eye), even though the two
eyes lack common visual experience in this case.  These results have
been interpreted to suggest that the structure of orientation maps
either is innately predetermined or, if it arises through
self-organization, is determined by external cues such as boundary
conditions or a ``scaffolding'' of horizontal connections.  We show,
to the contrary, that these results are the expected outcomes if
orientation maps develop through activity-instructed,
correlation-based development of the geniculocortical connections
without additional cues.  A weak, binocularly correlated orientation
map is known to exist before deprivation onset; we previously showed
how this can arise through activity-instructed development.  Now we
show that this initial correlation between the two eyes' maps can
persist or increase despite deprivation sufficient to cause massive
loss of the deprived eye's geniculocortical synaptic strength,
followed by reverse suture.  Given sufficient early correlated map
development, each map's fate is ``dynamically committed'': the two
eyes' maps will converge upon a common outcome, even if developing
independently.  This dynamic fate commitment is retained even after
severe deprivation.


Ken
 
        Kenneth D. Miller               telephone: (415) 476-8217
	Associate Professor		fax: (415) 476-4929
        Dept. of Physiology, UCSF	internet: ken at phy.ucsf.edu
        513 Parnassus			www: http://www.keck.ucsf.edu/~ken
        San Francisco, CA 94143-0444