title: Psychological and physiological responses to odor-evoked autobiographic memory.
abstract: OBJECTIVE
  The "Proust phenomenon" occurs when a certain smell evokes a specific memory. Recent studies have demonstrated that odor-evoked autobiographic memories are more emotional than those elicited by other sensory stimuli because of the direct neural communication between the olfactory system and the amygdala. The amygdala is known to regulate various physiological activities including the endocrine and immune systems; therefore, odor-evoked autobiographic memory may trigger various psychological and physiological responses; however, the responses elicited by this memory remains obscure. In this study, we aimed to investigate the psychological and physiological responses accompanying odor-evoked autobiographic memory.
  
  
  METHODS
  We recruited healthy male and female volunteers and investigated changes in their mood states and autonomic nervous, endocrine, and immune activities when autobiographic memory was evoked in the participants by asking them to smell an odor(s) that was nostalgic to them.
  
  
  RESULTS
  The autobiographic memories associated with positive emotion resulted in increased positive mood states, such as comfort and happiness, and decreased negative mood states, such as anxiety. Furthermore, heart rate was decreased, skin-conductance level was increased, and peripheral interleukin-2 level was decreased after smelling the nostalgic odor. These psychological and physiological responses were significantly correlated.
  
  
  CONCLUSIONS
  The present study suggests that odor-evoked autobiographic memory along with a positive feeling induce various physiological responses, including the autonomic nervous and immune activities. To the best of our knowledge, the present study is the first to observe an interaction between odor-evoked autobiographic memories and immune function.
authors.affiliation: Division of Cerebral Integration, Department of Cerebral Research, National Institute for Physiological Sciences, Aichi, Japan. mmatsu@nips.ac.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Matsunaga
authors.forename: Tokiko
authors.initials: T
authors.lastname: Isowa
authors.forename: Kaori
authors.initials: K
authors.lastname: Yamakawa
authors.forename: Yoko
authors.initials: Y
authors.lastname: Kawanishi
authors.forename: Hirohito
authors.initials: H
authors.lastname: Tsuboi
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Kaneko
authors.forename: Norihiro
authors.initials: N
authors.lastname: Sadato
authors.forename: Akiko
authors.initials: A
authors.lastname: Oshida
authors.forename: Atsushi
authors.initials: A
authors.lastname: Katayama
authors.forename: Mitsuyoshi
authors.initials: M
authors.lastname: Kashiwagi
authors.forename: Hideki
authors.initials: H
authors.lastname: Ohira
mesh_terms: D000328:Adult; D000339:Affect / Q000502:physiology; D001341:Autonomic Nervous System / Q000502:physiology; D002395:Catecholamines / Q000097:blood; D016207:Cytokines / Q000097:blood; D004644:Emotions / Q000502:physiology; D005260:Female; D006801:Humans; D008297:Male; D061212:Memory, Episodic; D009812:Odorants; D012903:Smell / Q000502:physiology*; D055815:Young Adult
chemical_list: D002395:Catecholamines; D016207:Cytokines