Mesches M H, Bianchin M, McGaugh J L
Department of Psychobiology, University of California, Irvine 92697-3800, USA.
Neurobiol Learn Mem. 1996 Nov;66(3):324-40. doi: 10.1006/nlme.1996.0073.
The aim of these experiments was to determine whether impaired retention performance in aversively motivated tasks, induced by blockade of amygdala AMPA receptors, is due to influences on mechanisms underlying memory retrieval or to other influences on performance. Rats received either footshock escape training (1 or 10 trials), or no foot shock, in a two-compartment straight alley and bilateral intra-amygdala infusions of the AMPA receptor antagonist CNQX (0.5 microgram) were subsequently administered prior to inhibitory avoidance retention testing 8 days later. The CNQX impaired, but did not block, inhibitory avoidance retention performance as indicated by the initial latencies to enter the shock compartment. The animals were then retained in the alley until they remained in the starting compartment for 100 consecutive s and entries into the shock compartment were recorded as errors. In both the controls and CNQX-treated groups, increases in amount of original training resulted in fewer errors, indicating memory for the escape training. Furthermore, regardless of the amount of original training (i.e., 0, 1, or 10 trials), CNQX-treated groups made more errors. Other experiments examined intra-amygdala CNQX effects on reactivity to footshock, locomotor activity, and anxiety. CNQX decreased reactivity to footshock, blocked shock-induced decreases in locomotor activity, and had an anxiolytic effect in an elevated plus maze comparable to that induced by midazolam (0.5 microgram). These findings suggest that intra-amygdala infusions of CNQX prior to retention testing affect inhibitory avoidance retention performance following aversive training by altering locomotor activity, reducing sensitivity to footshock, and reducing anxiety. The implications of these findings for hypotheses concerning amygdala function in aversively motivated learning and memory is discussed.
这些实验的目的是确定由杏仁核AMPA受体阻断所诱发的、在厌恶动机任务中出现的记忆保持能力受损，是由于对记忆提取所涉及机制的影响，还是对行为表现的其他影响。大鼠在两室直通道中接受足部电击逃避训练（1次或10次试验），或不接受足部电击，随后在8天后进行抑制性回避记忆保持测试前，双侧杏仁核内注射AMPA受体拮抗剂CNQX（0.5微克）。如进入电击室的初始潜伏期所示，CNQX损害了但并未阻断抑制性回避记忆保持表现。然后将动物留在通道中，直到它们在起始室中连续停留100秒，并将进入电击室的次数记录为错误次数。在对照组和CNQX处理组中，原始训练量的增加均导致错误次数减少，表明对逃避训练有记忆。此外，无论原始训练量如何（即0次、1次或10次试验），CNQX处理组的错误次数都更多。其他实验研究了杏仁核内注射CNQX对足部电击反应性、运动活动和焦虑的影响。CNQX降低了对足部电击的反应性，阻断了电击诱导的运动活动减少，并在高架十字迷宫中产生了与咪达唑仑（0.5微克）诱导的类似的抗焦虑作用。这些发现表明，在记忆保持测试前杏仁核内注射CNQX，通过改变运动活动、降低对足部电击的敏感性和减轻焦虑，影响了厌恶训练后的抑制性回避记忆保持表现。本文讨论了这些发现对于有关杏仁核在厌恶动机学习和记忆中功能的假说的意义。
