title: Balanced interhemispheric cortical activity is required for correct targeting of the corpus callosum.
abstract: Bilateral integration of sensory and associative brain processing is achieved by precise connections between homologous regions in the two hemispheres via the corpus callosum. These connections form postnatally, and unilateral deprivation of sensory or spontaneous cortical activity during a critical period severely disrupts callosal wiring. However, little is known about how this early activity affects precise circuit formation. Here, using in utero electroporation of reporter genes, optogenetic constructs, and direct disruption of activity in callosal neurons combined with whisker ablations, we show that balanced interhemispheric activity, and not simply intact cortical activity in either hemisphere, is required for functional callosal targeting. Moreover, bilateral ablation of whiskers in symmetric or asymmetric configurations shows that spatially symmetric interhemispheric activity is required for appropriate callosal targeting. Our findings reveal a principle governing axon targeting, where spatially balanced activity between regions is required to establish their appropriate connectivity.
authors.affiliation: Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Rodrigo
authors.initials: R
authors.lastname: Suárez
authors.affiliation: Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Laura R
authors.initials: LR
authors.lastname: Fenlon
authors.affiliation: Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Roger
authors.initials: R
authors.lastname: Marek
authors.affiliation: Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Lilach
authors.initials: L
authors.lastname: Avitan
authors.affiliation: Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Pankaj
authors.initials: P
authors.lastname: Sah
authors.affiliation: Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; School of Mathematics and Physics, The University of Queensland, Brisbane, QLD 4072, Australia.
authors.forename: Geoffrey J
authors.initials: GJ
authors.lastname: Goodhill
authors.affiliation: Queensland Brain Institute, The University of Queensland, Brisbane, QLD 4072, Australia; School of Biomedical Sciences, The University of Queensland, Brisbane, QLD 4072, Australia. Electronic address: richards@uq.edu.au.
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Richards
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D000831:Animals, Newborn; D003337:Corpus Callosum / Q000502:physiology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D051379:Mice; D009434:Neural Pathways / Q000502:physiology; D011247:Pregnancy