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VERSION:2.0
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METHOD:PUBLISH
BEGIN:VEVENT
DTSTAMP:20260918T112156Z
LAST-MODIFIED:-11130T050000Z
DTSTART:20111109T203000Z
DTEND:20111109T213000Z
UID:event251@bu.edu
URL:http://physics.bu.edu/internal/events/show/251
SUMMARY:Reorganization of columnar architecture in the growing visual corte
	x
DESCRIPTION:Featuring Wolfgang Keil\, Max-Planck Institute for Dynamics and
	 Self-Organization\nHosted by: Pankaj Mehta\n\nPart of the Biophysics/Conde
	nsed Matter Seminar Series.\n\nAbstract:The impressive ability of cortical 
	circuits to reorganize during and after the so-called critical period has b
	een demonstratedin numerous studies by artificially manipulating cortical a
	ctivity; e.g.\, by monocular deprivation. But what is the function of a per
	iod of relatively strong plasticity at such a late stage in normal developm
	ent? Here\, we propose that cortical circuitsmay remain plastic for an exte
	nded period in development to facilitate themodification of neuronal circui
	ts to adjust for cortical growth. In acute and chronic experiments\, we stu
	dy the layout of ocular dominance(OD) columns in cat primary visual cortex 
	during a period ofsubstantial postnatal growth. We find that despite a cons
	iderable sizeincrease of primary visual cortex\, the spacing between column
	s islargely preserved. In contrast\, their spatial arrangement changes syst
	ematically over this period. Whereas in young animals columns are more band
	-like\, layouts become more isotropic in mature animals. Interestingly\, th
	is reorganization is largest close to the peak of the critical period. We p
	ropose a novel mechanism of growth-induced reorganization of columnar circu
	its that is based on the “zigzag instability\,” a dynamical ins
	tability observed in several inanimatepattern-forming systems. We argue tha
	t this mechanism is inherent to awide class of models for the activity-depe
	ndent formation of ODcolumns. Analyzing one representative of this class\, 
	the ElasticNetwork model\, we show that this mechanism can account for the 
	preservation of column spacing and the specific mode of reorganization of O
	D columns that we observe. We conclude that column width ispreserved by sys
	tematic reorganization of neuronal selectivitiesduring cortical expansion a
	nd that this reorganization is welldescribed by the zigzag instability. Our
	 work suggests that corticalplasticity may play an important role in normal
	 development throughfacilitating growth-related modifications of neuronal c
	ircuits.
LOCATION:SCI 328\, 590 Commonwealth Avenue\, 02215
STATUS:CONFIRMED
CLASS:PUBLIC
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