Romano A G, Kachelries W J, Simansky K J, Harvey J A
Department of Pharmacology, Medical College of Pennsylvania, Philadelphia 19129, USA.
Pharmacol Biochem Behav. 1995 Oct;52(2):415-20. doi: 10.1016/0091-3057(95)00129-k.
Previous studies had demonstrated that in utero exposure to cocaine produces structural changes in the development of the rabbit's anterior cingulate cortex. Because the anterior cingulate cortex has been proposed to subserve a variety of cognitive processes including associative learning, we investigated the effects of intrauterine exposure to cocaine on the acquisition of the rabbit's classically conditioned nictitating membrane response. Adult, sexually mature rabbits born of dams that had received intravenous injections of either saline or cocaine (4 mg/kg, twice a day) from day 8 to day 29 of gestation were classically conditioned by pairing tone and light CSs with an airpuff US. Rabbits that had been exposed to cocaine in utero demonstrated a more rapid acquisition of CRs to a tone CS but not to a light CS as compared with saline controls. Control experiments indicated that the accelerated learning to the tone CS was not due to sensitization, pseudoconditioning, altered baseline rate of responding, an increased responsiveness to the airpuff US, or to a change in the intensity threshold of the tone CS for elicitation of CRs. We conclude that in utero exposure to cocaine alters the processing of auditory stimuli and this leads to an abnormally rapid acquisition of CRs. It is suggested that this functional consequence of prenatal exposure to cocaine is due to structural abnormalities in anterior cingulate cortex.
先前的研究表明，子宫内接触可卡因会使兔子前扣带回皮质的发育产生结构变化。由于前扣带回皮质被认为参与多种认知过程，包括联想学习，我们研究了子宫内接触可卡因对兔子经典条件反射性瞬膜反应习得的影响。成年、性成熟的兔子，其母兔在妊娠第8天至第29天接受静脉注射生理盐水或可卡因（4毫克/千克，每日两次），通过将音调与光条件刺激（CS）与吹气非条件刺激（US）配对进行经典条件反射训练。与生理盐水对照组相比，子宫内接触可卡因的兔子对音调CS表现出更快的条件反应（CR）习得，但对光CS则不然。对照实验表明，对音调CS的加速学习并非由于敏感化、假性条件反射、反应基线率改变、对吹气US的反应性增加或音调CS引发CR的强度阈值变化。我们得出结论，子宫内接触可卡因会改变听觉刺激的处理过程，进而导致CR的异常快速习得。有人认为，产前接触可卡因的这种功能后果是由于前扣带回皮质的结构异常所致。
