title: The Idea Is Good, but…: Failure to Replicate Associations of Oxytocinergic Polymorphisms with Face-Inversion in the N170.
abstract: BACKGROUND
  In event-related potentials, the N170 manifests itself especially in reaction to faces. In the healthy population, face-inversion leads to stronger negative amplitudes and prolonged latencies of the N170, effects not being present in patients with autism-spectrum-disorder (ASD). ASD has frequently been associated with differences in oxytocinergic neurotransmission. This ERP-study aimed to investigate the face-inversion effect in association with oxytocinergic candidate genes. It was expected that risk-allele-carriers of the oxytocin-receptor-gene-polymorphism (rs53576) and of CD38 (rs379863) responded similar to upright and inverted faces as persons with ASD. Additionally, reactions to different facial emotional expressions were studied. As there have been difficulties with replications of those molecular genetic association studies, we aimed to replicate our findings in a second study.
  
  
  METHODS
  Seventy-two male subjects in the first-, and seventy-eight young male subjects in the replication-study conducted a face-inversion-paradigm, while recording EEG. DNA was extracted from buccal cells.
  
  
  RESULTS
  Results revealed stronger N170-amplitudes and longer latencies in reaction to inverted faces in comparison to upright ones. Furthermore, effects of emotion on N170 were evident. Those effects were present in the first and in the second study. Whereas we found molecular-genetic associations of oxytocinergic polymorphisms with the N170 in the first study, we failed to do so in the replication sample.
  
  
  CONCLUSIONS
  Results indicate that a deeper theoretical understanding of this research-field is needed, in order to generate possible explanations for these findings. Results, furthermore, support the hypotheses that success of reproducibility is correlated with strength of lower original p-values and larger effect sizes in the original study.
authors.affiliation: Justus Liebig University Giessen, Department of Psychology, Personality and Biological Psychology, Otto-Behaghel-Strasse 10F, 35394 Giessen, Germany.
authors.forename: Aisha J L
authors.initials: AJ
authors.lastname: Munk
authors.affiliation: Justus Liebig University Giessen, Department of Psychology, Psychotherapy and Systems Neuroscience, Otto-Behaghel-Strasse 10F, 35394 Giessen, Germany.
authors.forename: Andrea
authors.initials: A
authors.lastname: Hermann
authors.affiliation: Justus Liebig University Giessen, Faculty of Medicine, Center for Psychiatry and Psychotherapy, Am Steg 28, 35392 Giessen, Germany.
authors.forename: Jasmin
authors.initials: J
authors.lastname: El Shazly
authors.affiliation: Justus Liebig University Giessen, Department of Psychology, Personality and Biological Psychology, Otto-Behaghel-Strasse 10F, 35394 Giessen, Germany.
authors.forename: Phillip
authors.initials: P
authors.lastname: Grant
authors.affiliation: Justus Liebig University Giessen, Department of Psychology, Personality and Biological Psychology, Otto-Behaghel-Strasse 10F, 35394 Giessen, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hennig
mesh_terms: D000328:Adult; D000067877:Autism Spectrum Disorder / Q000235:genetics* / Q000503:physiopathology; D004569:Electroencephalography; D004644:Emotions; D005071:Evoked Potentials / Q000235:genetics*; D005145:Face; D056726:Genetic Association Studies; D005838:Genotype; D006801:Humans; D008297:Male; D018045:Receptors, Oxytocin / Q000235:genetics*; D012701:Serotonin / Q000235:genetics / Q000378:metabolism; D009435:Synaptic Transmission / Q000235:genetics; D014796:Visual Perception / Q000502:physiology
chemical_list: C569600:OXTR protein, human; D018045:Receptors, Oxytocin; D012701:Serotonin