title: Comparison of two intracranial self-stimulation (ICSS) paradigms in C57BL/6 mice: head-dipping and place-learning.
abstract: A variety of intracranial self-stimulation (ICSS) paradigms have been utilized for investigations of reward. Among them, nose-poking and spatial-preference paradigms are known to be relatively more resistant to the effects of drug-induced motor-deficits in rat studies, although these two ICSS paradigms have not been directly compared in previous studies. In the present study, head-dipping and place-learning (forms of nose-poking and spatial-preference tasks, respectively) paradigms with lateral hypothalamus stimulation were systematically analyzed using C57BL/6 mice in the presence and absence of two motor-deficit-inducing drugs: tolperisone and harmaline. Rapid acquisition and rapid extinction patterns of ICSS responding were observed in the head-dipping and place-learning paradigms. In contrast to these pre-drug similarities in responding, dramatic differences were noted after drug administration. Tolperisone significantly reduced head-dipping but not place-learning ICSS responding. Similarly, reduction of ICSS responding after harmaline was more pronounced in the head-dipping task. Therefore, the place-learning paradigm may be superior for the assessment of reward values under motor-deficit-inducing conditions in C57BL/6 mice. The relative benefits and disadvantages of both ICSS paradigms are discussed. Combinations of complementary ICSS paradigms using mice may be useful for further investigations of the molecular bases of reward.
authors.affiliation: Laboratory for Neurobiology of Emotion, Brain Science Institute, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan. ikedak@prit.go.jp
authors.forename: K
authors.initials: K
authors.lastname: Ikeda
authors.forename: S J
authors.initials: SJ
authors.lastname: Moss
authors.forename: S C
authors.initials: SC
authors.lastname: Fowler
authors.forename: H
authors.initials: H
authors.lastname: Niki
mesh_terms: D000818:Animals; D001245:Association Learning / Q000502:physiology; D001931:Brain Mapping; D002755:Choice Behavior / Q000502:physiology*; D003214:Conditioning, Classical / Q000502:physiology*; D004558:Electric Stimulation; D007031:Hypothalamus / Q000502:physiology; D051379:Mice; D008810:Mice, Inbred C57BL; D009042:Motivation; D009043:Motor Activity / Q000502:physiology*; D012653:Self Stimulation / Q000502:physiology*; D012931:Social Environment; D013239:Stereotyped Behavior / Q000502:physiology*