title: Enhancement of acoustic prepulse inhibition by contextual fear conditioning in mice is maintained even after contextual fear extinction.
abstract: Prepulse inhibition (PPI) of the acoustic startle response is one of the few and major paradigms for investigating sensorimotor gating systems in humans and rodents in a similar fashion. PPI deficits are observed not only in patients with schizophrenia, but also in patients with anxiety disorders. Previous studies have shown that PPI in rats can be enhanced by auditory fear conditioning. In this study, we evaluated the effects of contextual fear conditioning (FC) for six times a day and fear extinction (FE) for seven days on PPI in mice. C57BL/6J mice (male, 8-12 weeks) were divided into three groups; no-FC (control), FC and FC + FE. We measured PPI at the following three time points, (1) baseline before FC, (2) after FC, and (3) after FE. The results showed that PPI was increased after FC. Moreover, the enhanced PPI following FC was observed even after FE with decreased freezing behaviors. These results suggested contextual fear conditioning could enhance acoustic PPI, and that contextual fear extinction could decrease freezing behaviors, but not acoustic PPI.
authors.affiliation: Department of Integrative Neurophysiology, Chiba University Graduate School of Medicine, 1-8-1 Inohana, Chiba 260-8670, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Ishii
authors.forename: Daisuke
authors.initials: D
authors.lastname: Matsuzawa
authors.forename: Yuko
authors.initials: Y
authors.lastname: Fujita
authors.forename: Chihiro
authors.initials: C
authors.lastname: Sutoh
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohtsuka
authors.forename: Shingo
authors.initials: S
authors.lastname: Matsuda
authors.forename: Nobuhisa
authors.initials: N
authors.lastname: Kanahara
authors.forename: Kenji
authors.initials: K
authors.lastname: Hashimoto
authors.forename: Masaomi
authors.initials: M
authors.lastname: Iyo
authors.forename: Eiji
authors.initials: E
authors.lastname: Shimizu
mesh_terms: D000161:Acoustic Stimulation / Q000009:adverse effects; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D003214:Conditioning, Classical / Q000502:physiology*; D005108:Extinction, Psychological / Q000502:physiology; D005239:Fear; D006185:Habituation, Psychophysiologic / Q000502:physiology; D007266:Inhibition, Psychological; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D013216:Reflex, Startle / Q000502:physiology*; D055139:Sensory Gating / Q000502:physiology*