title: Disrupted cortical map and absence of cortical barrels in growth-associated protein (GAP)-43 knockout mice.
abstract: There is strong evidence that growth-associated protein (GAP-43), a protein found only in the nervous system, regulates the response of neurons to axonal guidance signals. However, its role in complex spatial patterning in cerebral cortex has not been explored. We show that mice lacking GAP-43 expression (-/-) fail to establish the ordered whisker representation (barrel array) normally found in layer IV of rodent primary somatosensory cortex. Thalamocortical afferents to -/- cortex form irregular patches in layer IV within a poorly defined cortical field, which varies between hemispheres, rather than the stereotypic, whisker-specific, segregated map seen in normal animals. Furthermore, many thalamocortical afferents project abnormally to widely separated cortical targets. Taken together, our findings indicate a loss of identifiable whisker territories in the GAP-43 -/- mouse cortex. Here, we present a disrupted somatotopic map phenotype in cortex, in clear contrast to the blurring of boundaries within an ordered whisker map in other barrelless mutants. Our results indicate that GAP-43 expression is critical for the normal establishment of ordered topography in barrel cortex.
authors.affiliation: Department of Anatomy and Cell Biology, State University of New York Health Science Center, Syracuse, NY 13210, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Maier
authors.forename: S
authors.initials: S
authors.lastname: Mani
authors.forename: S L
authors.initials: SL
authors.lastname: Donovan
authors.forename: D
authors.initials: D
authors.lastname: Soppet
authors.forename: L
authors.initials: L
authors.lastname: Tessarollo
authors.forename: J S
authors.initials: JS
authors.lastname: McCasland
authors.forename: K F
authors.initials: KF
authors.lastname: Meiri
mesh_terms: D000818:Animals; D001303:Auditory Cortex / Q000166:cytology / Q000502:physiology; D001370:Axonal Transport; D001931:Brain Mapping; D003433:Crosses, Genetic; D003576:Electron Transport Complex IV / Q000032:analysis; D005260:Female; D007839:Functional Laterality; D019922:GAP-43 Protein / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D006579:Heterozygote; D007150:Immunohistochemistry; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D010641:Phenotype; D016133:Polymerase Chain Reaction; D013003:Somatosensory Cortex / Q000166:cytology / Q000502:physiology*; D013239:Stereotyped Behavior; D014278:Trigeminal Nuclei / Q000502:physiology; D014738:Vibrissae / Q000294:innervation*
chemical_list: D019922:GAP-43 Protein; D003576:Electron Transport Complex IV