title: Functional gene polymorphisms in the serotonin system and traumatic life events modulate the neural basis of fear acquisition and extinction.
abstract: Fear acquisition and extinction are crucial mechanisms in the etiology and maintenance of anxiety disorders. Moreover, they might play a pivotal role in conveying the influence of genetic and environmental factors on the development of a (more or less) stronger proneness for, or resilience against psychopathology. There are only few insights in the neurobiology of genetically and environmentally based individual differences in fear learning and extinction. In this functional magnetic resonance imaging study, 74 healthy subjects were investigated. These were invited according to 5-HTTLPR/rs25531 (S+ vs. L(A)L(A); triallelic classification) and TPH2 (G(-703)T) (T+ vs. T-) genotype. The aim was to investigate the influence of genetic factors and traumatic life events on skin conductance responses (SCRs) and neural responses (amygdala, insula, dorsal anterior cingulate cortex (dACC) and ventromedial prefrontal cortex (vmPFC)) during acquisition and extinction learning in a differential fear conditioning paradigm. Fear acquisition was characterized by stronger late conditioned and unconditioned responses in the right insula in 5-HTTLPR S-allele carriers. During extinction traumatic life events were associated with reduced amygdala activation in S-allele carriers vs. non-carriers. Beyond that, T-allele carriers of the TPH2 (G(-703)T) polymorphism with a higher number of traumatic life events showed enhanced responsiveness in the amygdala during acquisition and in the vmPFC during extinction learning compared with non-carriers. Finally, a combined effect of the two polymorphisms with higher responses in S- and T-allele carriers was found in the dACC during extinction. The results indicate an increased expression of conditioned, but also unconditioned fear responses in the insula in 5-HTTLPR S-allele carriers. A combined effect of the two polymorphisms on dACC activation during extinction might be associated with prolonged fear expression. Gene-by-environment interactions in amygdala and vmPFC activation may reflect a neural endophenotype translating genetic and adverse environmental influences into vulnerability for or resilience against developing affective psychopathology.
authors.affiliation: Department of Psychotherapy and Systems Neuroscience, Justus Liebig University Giessen, Giessen, Germany. andrea.hermann@psychol.uni-giessen.de
authors.forename: Andrea
authors.initials: A
authors.lastname: Hermann
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Küpper
authors.forename: Anja
authors.initials: A
authors.lastname: Schmitz
authors.forename: Bertram
authors.initials: B
authors.lastname: Walter
authors.forename: Dieter
authors.initials: D
authors.lastname: Vaitl
authors.forename: Jürgen
authors.initials: J
authors.lastname: Hennig
authors.forename: Rudolf
authors.initials: R
authors.lastname: Stark
authors.forename: Katharina
authors.initials: K
authors.lastname: Tabbert
mesh_terms: D000328:Adult; D000483:Alleles; D001921:Brain / Q000473:pathology / Q000502:physiology; D001931:Brain Mapping / Q000379:methods; D003213:Conditioning, Psychological / Q000502:physiology; D004777:Environment; D005108:Extinction, Psychological / Q000502:physiology; D005239:Fear; D005260:Female; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008957:Models, Genetic; D010641:Phenotype; D011110:Polymorphism, Genetic; D012701:Serotonin / Q000378:metabolism*; D012867:Skin / Q000473:pathology; D014947:Wounds and Injuries
chemical_list: D012701:Serotonin