title: Spatial pattern of spontaneous retinal waves instructs retinotopic map refinement more than activity frequency.
abstract: Spontaneous activity during early development is necessary for the formation of precise neural connections, but it remains uncertain whether activity plays an instructive or permissive role in brain wiring. In the visual system, retinal ganglion cell (RGC) projections to the brain form two prominent sensory maps, one reflecting eye of origin and the other retinotopic location. Recent studies provide compelling evidence supporting an instructive role for spontaneous retinal activity in the development of eye-specific projections, but evidence for a similarly instructive role in the development of retinotopy is more equivocal. Here, we report on experiments in which we knocked down the expression of β2-containing nicotinic acetylcholine receptors (β2-nAChRs) specifically in the retina through a Cre-loxP recombination strategy. Overall levels of spontaneous retinal activity in retina-specific β2-nAChR mutant mice (Rx-β2cKO), examined in vitro and in vivo, were reduced to a degree comparable to that observed in whole animal β2-nAChR mouse mutants (β2KO). However, many residual spontaneous waves in Rx-β2cKO mice displayed local propagating features with strong correlations between nearby but not distant RGCs typical of waves observed in wild-type (WT) but not β2KO mice. We further observed that eye-specific segregation was disrupted in Rx-β2cKO mice, but retinotopy was spared in a competition-dependent manner. These results suggest that propagating patterns of spontaneous retinal waves are essential for normal development of the retinotopic map, even while overall activity levels are significantly reduced, and support an instructive role for spontaneous retinal activity in both eye-specific segregation and retinotopic refinement.
authors: Department of Neurobiology, Yale University, New Haven, CT, 06510.
authors: Hong-Ping
authors: HP
authors: Xu
authors: Department of Neurobiology, Yale University, New Haven, CT, 06510.
authors: Timothy J
authors: TJ
authors: Burbridge
authors: Department of Ophthalmology and Visual Science, Yale University, New Haven, CT, 06510.
authors: Ming-Gang
authors: MG
authors: Chen
authors: Department of Neurobiology, Yale University, New Haven, CT, 06510.
authors: Xinxin
authors: X
authors: Ge
authors: Department of Neurobiology, Yale University, New Haven, CT, 06510.
authors: Yueyi
authors: Y
authors: Zhang
authors: Department of Ophthalmology and Visual Science, Yale University, New Haven, CT, 06510.
authors: Zhimin Jimmy
authors: ZJ
authors: Zhou
authors: Department of Neurobiology, Yale University, New Haven, CT, 06510.|Department of Ophthalmology and Visual Science, Yale University, New Haven, CT, 06510.|Kavli Institute of Neuroscience, Yale University, New Haven, CT, 06510.
authors: Michael C
authors: MC
authors: Crair
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000596:Amino Acids / Q000378:metabolism; D000818:Animals; D001931:Brain Mapping; D020013:Calcium Signaling / Q000502:physiology; D005786:Gene Expression Regulation / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008822:Mice, Transgenic; D011978:Receptors, Nicotinic / Q000235:genetics / Q000378:metabolism; D012160:Retina / Q000166:cytology*; D012165:Retinal Ganglion Cells / Q000502:physiology*; D013477:Superior Colliculi; D014795:Visual Pathways / Q000166:cytology / Q000196:embryology / Q000254:growth & development
chemical_list: D000596:Amino Acids; D049452:Green Fluorescent Proteins; D011978:Receptors, Nicotinic; C098463:dolaisoleucine
keywords: activity-dependent; retinotopy; vision