title: Biochemical specificity of von Economo neurons in hominoids.
abstract: OBJECTIVE
  Von Economo neurons (VENs) are defined by their thin, elongated cell body and long dendrites projecting from apical and basal ends. These distinctive neurons are mostly present in anterior cingulate (ACC) and fronto-insular (FI) cortex, with particularly high densities in cetaceans, elephants, and hominoid primates (i.e., humans and apes). This distribution suggests that VENs contribute to specializations of neural circuits in species that share both large brain size and complex social cognition, possibly representing an adaptation to rapidly relay socially-relevant information over long distances across the brain. Recent evidence indicates that unique patterns of protein expression may also characterize VENs, particularly involving molecules that are known to regulate gut and immune function.
  
  
  METHODS
  In this study, we used quantitative stereologic methods to examine the expression of three such proteins that are localized in VENs-activating-transcription factor 3 (ATF3), interleukin 4 receptor (IL4Rα), and neuromedin B (NMB). We quantified immunoreactivity against these proteins in different morphological classes of ACC layer V neurons of hominoids.
  
  
  RESULTS
  Among the different neuron types analyzed (pyramidal, VEN, fork, enveloping, and other multipolar), VENs showed the greatest percentage that displayed immunostaining. Additionally, a higher proportion of VENs in humans were immunoreactive to ATF3, IL4Rα, and NMB than in other apes. No other ACC layer V neuron type displayed a significant species difference in the percentage of immunoreactive neurons.
  
  
  CONCLUSIONS
  These findings demonstrate that phylogenetic variation exists in the protein expression profile of VENs, suggesting that humans might have evolved biochemical specializations for enhanced interoceptive sensitivity.
authors.affiliation: Department of Anthropology, The George Washington University, Washington, DC 20052, USA.
authors.forename: Cheryl D
authors.initials: CD
authors.lastname: Stimpson
authors.forename: Nicole A
authors.initials: NA
authors.lastname: Tetreault
authors.forename: John M
authors.initials: JM
authors.lastname: Allman
authors.forename: Bob
authors.initials: B
authors.lastname: Jacobs
authors.forename: Camilla
authors.initials: C
authors.lastname: Butti
authors.forename: Patrick R
authors.initials: PR
authors.lastname: Hof
authors.forename: Chet C
authors.initials: CC
authors.lastname: Sherwood
mesh_terms: D051700:Activating Transcription Factor 3 / Q000502:physiology; D000328:Adult; D000818:Animals; D002452:Cell Count; D002540:Cerebral Cortex / Q000502:physiology*; D005260:Female; D015186:Hominidae / Q000145:classification / Q000502:physiology*; D006801:Humans; D016674:Hylobatidae / Q000502:physiology; D021621:Imaging, Three-Dimensional; D007150:Immunohistochemistry; D008297:Male; D008875:Middle Aged; D015287:Neurokinin B / Q000031:analogs & derivatives / Q000502:physiology; D009474:Neurons / Q000145:classification / Q000502:physiology*; D019948:Receptors, Interleukin-4 / Q000502:physiology; D012919:Social Behavior; D055815:Young Adult
chemical_list: D051700:Activating Transcription Factor 3; D019948:Receptors, Interleukin-4; D015287:Neurokinin B; C038393:neuromedin B