Pavlovian conditioning of emotional responses to olfactory and contextual stimuli: a potential model for the development and expression of chemical intolerance

Ann N Y Acad Sci. 2001 Mar;933:291-309. doi: 10.1111/j.1749-6632.2001.tb05832.x.


Chemical intolerance (CI) in humans is a poorly understood phenomenon of uncertain etiology, seemingly influenced by multiple factors both within and between affected individuals. Several authors have suggested that the development of CI in some individuals may be due, at least in part, to Pavlovian conditioning processes in which the expression of overt symptoms to certain substances reflects classically conditioned responses to previously neutral olfactory and contextual stimuli. In this paper, we describe the potential relationship between olfactory and contextual conditioning in experimental animals and the development and expression of CI in humans. Furthermore, as significant advances have been made in delineating the brain areas that underlie these learned responses, we also review recent research on the contributions of the amygdala and perirhinal cortical region to olfactory and contextual fear conditioning.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Review

MeSH terms

  • Amygdala / physiopathology
  • Animals
  • Association Learning / physiology*
  • Brain Mapping
  • Conditioning, Classical / physiology*
  • Electroshock
  • Emotions / physiology*
  • Fear / physiology
  • Hippocampus / physiopathology
  • Humans
  • Male
  • Models, Neurological
  • Models, Psychological
  • Motor Activity
  • Multiple Chemical Sensitivity / physiopathology*
  • Multiple Chemical Sensitivity / psychology
  • N-Methylaspartate / toxicity
  • Odorants*
  • Olfactory Pathways / physiopathology
  • Rats
  • Rats, Sprague-Dawley
  • Reaction Time
  • Sick Building Syndrome / physiopathology
  • Sick Building Syndrome / psychology
  • Single-Blind Method


  • N-Methylaspartate