title: Genealogical correspondence of a forebrain centre implies an executive brain in the protostome-deuterostome bilaterian ancestor.
abstract: Orthologous genes involved in the formation of proteins associated with memory acquisition are similarly expressed in forebrain centres that exhibit similar cognitive properties. These proteins include cAMP-dependent protein kinase A catalytic subunit (PKA-Cα) and phosphorylated Ca(2+)/calmodulin-dependent protein kinase II (pCaMKII), both required for long-term memory formation which is enriched in rodent hippocampus and insect mushroom bodies, both implicated in allocentric memory and both possessing corresponding neuronal architectures. Antibodies against these proteins resolve forebrain centres, or their equivalents, having the same ground pattern of neuronal organization in species across five phyla. The ground pattern is defined by olfactory or chemosensory afferents supplying systems of parallel fibres of intrinsic neurons intersected by orthogonal domains of afferent and efferent arborizations with local interneurons providing feedback loops. The totality of shared characters implies a deep origin in the protostome-deuterostome bilaterian ancestor of elements of a learning and memory circuit. Proxies for such an ancestral taxon are simple extant bilaterians, particularly acoels that express PKA-Cα and pCaMKII in discrete anterior domains that can be properly referred to as brains.
authors.affiliation: Department of Neuroscience, School of Mind, Brain, and Behavior, University of Arizona, Tucson, AZ 85721, USA gwolffneuro@gmail.com.
authors.forename: Gabriella H
authors.identifier: http://orcid.org/0000-0002-0075-4975
authors.initials: GH
authors.lastname: Wolff
authors.affiliation: Department of Neuroscience, School of Mind, Brain, and Behavior, University of Arizona, Tucson, AZ 85721, USA Center for Insect Science, University of Arizona, Tucson, AZ 85721, USA.
authors.forename: Nicholas J
authors.identifier: http://orcid.org/0000-0002-1115-1774
authors.initials: NJ
authors.lastname: Strausfeld
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal; D005075:Biological Evolution; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2 / Q000235:genetics / Q000378:metabolism; D054751:Cyclic AMP-Dependent Protein Kinase Catalytic Subunits / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation / Q000502:physiology; D006056:Golgi Apparatus; D007448:Invertebrates / Q000033:anatomy & histology* / Q000235:genetics / Q000502:physiology; D024521:Mushroom Bodies / Q000033:anatomy & histology* / Q000502:physiology; D016548:Prosencephalon / Q000033:anatomy & histology* / Q000502:physiology; D014404:Tubulin; D014714:Vertebrates / Q000033:anatomy & histology* / Q000235:genetics / Q000502:physiology
chemical_list: D000911:Antibodies, Monoclonal; D014404:Tubulin; D054751:Cyclic AMP-Dependent Protein Kinase Catalytic Subunits; C463959:protein kinase A Calpha; D054732:Calcium-Calmodulin-Dependent Protein Kinase Type 2
keywords: convergence; evolution; hippocampus; homology; mushroom body