title: Hippocampal theta rhythm and drug-related reward-seeking behavior: an analysis of cocaine-induced conditioned place preference in rats.
abstract: Drug cravings are elicited by environmental stimuli associated with the rewarding effects of drugs. As an animal model of such associative learning, conditioned place preference (CPP) is widely used. Since the hippocampus is closely related to reward memory and the hippocampal local field potential (LFP), and in particular the theta rhythm is known to be associated with bodily movements, the theta rhythm might be one of the key neural substrates. On the basis of this assumption, we recorded the behaviors and hippocampal LFP of eight rats during cocaine-induced acquisition and expression of CPP. The earliest appearance of phase-locked theta activity was observed before the rats entered the cocaine-paired environment after conditioning; after entrance, the theta disappeared. This phase-locked theta was stronger when the rats stayed for a long time in the cocaine-paired environment. Our observation suggested that the phase-locked hippocampal theta rhythm is related to the approaching behavior of the rat caused by reward memory. Thus, the role of the hippocampus in drug craving should be emphasized further.
authors.affiliation: SHIMOJO Implicit Brain Function Project, Exploratory Research for Advanced Technology, Japan Science and Technology Agency, NTT Atsugi Research and Development Center 3-1 Morinosatowakamiya, Atsugi-shi, Kanagawa 243-0198, Japan. ytakano@cs.brl.ntt.co.jp
authors.forename: Yuji
authors.initials: Y
authors.lastname: Takano
authors.forename: Tomoko
authors.initials: T
authors.lastname: Tanaka
authors.forename: Haruka
authors.initials: H
authors.lastname: Takano
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Hironaka
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D003042:Cocaine / Q000494:pharmacology*; D019970:Cocaine-Related Disorders / Q000503:physiopathology*; D018765:Dopamine Uptake Inhibitors / Q000494:pharmacology; D005106:Exploratory Behavior / Q000187:drug effects* / Q000502:physiology; D006624:Hippocampus / Q000187:drug effects* / Q000502:physiology; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D012201:Reward; D013826:Theta Rhythm / Q000187:drug effects*
chemical_list: D018765:Dopamine Uptake Inhibitors; D003042:Cocaine