One-trial object recognition memory in the domestic rabbit (Oryctolagus cuniculus) is disrupted by NMDA receptor antagonists

Behav Brain Res. 2013 Aug 1;250:62-73. doi: 10.1016/j.bbr.2013.04.049. Epub 2013 May 4.


The spontaneous response to novelty is the basis of one-trial object recognition tests for the study of object recognition memory (ORM) in rodents. We describe an object recognition task for the rabbit, based on its natural tendency to scent-mark ("chin") novel objects. The object recognition task comprised a 15min sample phase in which the rabbit was placed into an open field arena containing two similar objects, then removed for a 5-360min delay, and then returned to the same arena that contained one object similar to the original ones ("Familiar") and one that differed from the original ones ("Novel"), for a 15min test phase. Chin-marks directed at each of the objects were registered. Some animals received injections (sc) of saline, ketamine (1mg/kg), or MK-801 (37μg/kg), 5 or 20min before the sample phase. We found that chinning decreased across the sample phase, and that this response showed stimulus specificity, a defining characteristic of habituation: in the test phase, chinning directed at the Novel, but not Familiar, object was increased. Chinning directed preferentially at the novel object, which we interpret as novelty-induced sensitization and the behavioral correlate of ORM, was promoted by tactile/visual and spatial novelty. ORM deficits were induced by pre-treatment with MK-801 and, to a lesser extent, ketamine. Novel object discrimination was not observed after delays longer than 5min. These results suggest that short-term habituation and sensitization, not long-term memory, underlie novel object discrimination in this test paradigm.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Disease Models, Animal
  • Dizocilpine Maleate / toxicity
  • Dose-Response Relationship, Drug
  • Excitatory Amino Acid Antagonists / toxicity*
  • Exploratory Behavior / drug effects
  • Female
  • Ketamine / toxicity
  • Male
  • Memory Disorders / chemically induced*
  • Memory Disorders / physiopathology*
  • Rabbits
  • Recognition, Psychology / drug effects*
  • Sex Characteristics
  • Statistics, Nonparametric
  • Time Factors


  • Excitatory Amino Acid Antagonists
  • Ketamine
  • Dizocilpine Maleate