Carelli R M
Department of Psychology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3270, USA.
Synapse. 2000 Mar 1;35(3):238-42. doi: 10.1002/(SICI)1098-2396(20000301)35:3<238::AID-SYN10>3.0.CO;2-Y.
Electrophysiological recording procedures were used in behaving rats (n = 11) to examine the responsiveness of nucleus accumbens (Acb) neurons to stimuli associated with intravenous cocaine delivery during self-administration sessions. Of 208 Acb neurons recorded during cocaine (0.33 mg/inf) self-administration sessions, 78 cells exhibited one of four types of patterned discharges (increases and/or decreases in firing rate) immediately before and/or following the cocaine-reinforced response. All phasically active Acb cells were examined in test sessions consisting of "probe" trials (18-20 per session) during which either the drug only was delivered (0.33 mg/inf cocaine, 6 sec) or the stimulus only (tone-houselight, 20 sec) was randomly presented by the computer, interspersed between reinforced lever press responses. Results show that Acb cells that exhibit postresponse changes in firing rate within seconds of the reinforced response appear to be controlled, at least in part, by the stimulus paired with cocaine delivery during the self-administration session and not via a direct pharmacological action of cocaine. In contrast, neurons displaying exclusively preresponse activity do not appear to be influenced by presentation of the drug-associated stimulus or by a direct pharmacological action of the cocaine, but may be related to initiation of the operant response. These findings are discussed with respect to the role of the Acb in mediating conditioned responses associated with drug reinforcement.
采用电生理记录程序，对11只行为活跃的大鼠进行实验，以检测伏隔核（Acb）神经元在自我给药期间对与静脉注射可卡因相关刺激的反应性。在可卡因（0.33毫克/注射）自我给药期间记录的208个Acb神经元中，78个细胞在可卡因强化反应之前和/或之后，表现出四种模式放电类型之一（放电频率增加和/或减少）。在由“探测”试验组成的测试环节中（每次测试18 - 20次），对所有具有相位活性的Acb细胞进行检测，在此期间，计算机随机呈现仅给予药物（0.33毫克/注射可卡因，持续6秒）或仅给予刺激（音调 - 饲养箱灯光，持续20秒），并穿插在强化的杠杆按压反应之间。结果表明，在强化反应后数秒内表现出放电频率变化的Acb细胞，似乎至少部分受自我给药期间与可卡因给药配对的刺激所控制，而非可卡因的直接药理作用。相比之下，仅表现出反应前活动的神经元似乎不受与药物相关刺激的呈现或可卡因直接药理作用的影响，但可能与操作性反应的启动有关。针对Acb在介导与药物强化相关的条件反应中的作用，对这些发现进行了讨论。
