TOPIC HIGHLIGHT Role of classical conditioning in learning gastrointestinal symptoms

Nausea and/or vomiting are aversive gastrointestinal (GI) symptoms. Nausea and vomit ing mani fest unconditionally after a nauseogenic experience. However, there is correlative, quasiexperimental and experimental evidence that nausea and vomiting can also be learned via classical (Pavlovian) conditioning and might occur in anticipation of the nauseogenic event. Classical conditioning of nausea can develop with chemotherapy in cancer patients. Initially, nausea and vomiting occur during and after the administration of cytotoxic drugs (post-treatment nausea and vomiting) as unconditioned responses (UR). In addition, 20%-30 % of cancer patients receiving chemotherapy report these side effects, despite antiemetic medication, when being re-exposed to th