title: To inhale or not to inhale: conditioned avoidance in breathing behavior in an odor--20% CO2 paradigm.
abstract: This study investigated breathing behavior in an odor-CO2-inhalation fear conditioning paradigm. A differential conditioning paradigm was applied in 55 participants. Both acquisition and extinction consisted of three CS+ and three CS- trials. Diluted ammonia and butyric acid served as conditional odor cues (CSs); inhalation of 20% CO2-enriched as US. The US was presented 10s after CS+ onset and both stimuli co-terminated 30s later. Subjective anxiety and US-expectancy were measured online upon presentation of the CSs. Respiratory behavior showed a biphasic pattern during CS+ acquisition trials. Participants paradoxically lowered their ventilation first; an increased ventilation was observed only towards the end of the trial. Extinction of this breathing inhibition was found. Participants avoiding the CO2 during acquisition did not show a reduction in fear from acquisition to extinction, whereas Non-avoiders did. We conclude that paradoxical decreases in ventilation constitute a relevant behavioral index of fear in CO2-inhalation paradigms.
authors.affiliation: Department of Psychology, University of Leuven, Tiensestraat 102, 3000 Leuven, Belgium.
authors.forename: Stien
authors.initials: S
authors.lastname: Fannes
authors.forename: Ilse
authors.initials: I
authors.lastname: Van Diest
authors.forename: Ann
authors.initials: A
authors.lastname: Meulders
authors.forename: Steven
authors.initials: S
authors.lastname: De Peuter
authors.forename: Debora
authors.initials: D
authors.lastname: Vansteenwegen
authors.forename: Omer
authors.initials: O
authors.lastname: Van den Bergh
mesh_terms: D000293:Adolescent; D000328:Adult; D001007:Anxiety / Q000523:psychology; D001362:Avoidance Learning / Q000502:physiology*; D002245:Carbon Dioxide; D003214:Conditioning, Classical; D005108:Extinction, Psychological; D005260:Female; D006801:Humans; D001239:Inhalation / Q000502:physiology*; D008297:Male; D008875:Middle Aged; D009812:Odorants; D011569:Psychiatric Status Rating Scales; D012649:Self Concept; D013997:Time Factors
chemical_list: D002245:Carbon Dioxide