Measurement of Neurotransmitters Related to Learning and Memory by Brain Dialysis.

有证据表明，儿茶酚胺能神经递质在猴前额叶皮层的认知过程中发挥重要作用。本研究采用在体灌流透析结合高效液相色谱电化学检测技术，探讨了恒河猴前额叶皮层神经递质对空间短时记忆功能的影响。为此，两只猴子进行了8秒延迟反应任务，这是与空间短时记忆，和控制，非延迟位置歧视，任务。我们通过植入前额皮质的透析探针测量多巴胺和去甲肾上腺素的含量。这两项任务每20分钟交替一次。通过比较猴子在执行这两种任务时释放的递质的数量，我们可以估计前额叶皮层中每种递质在空间短时记忆功能中的作用，在许多地方，多巴胺的释放量在延迟反应任务中比在控制任务中更高。这些探针位于主沟周围。延长延迟间隔导致多巴胺释放的升高，这表明长延迟条件下前额叶皮层的活动更高。单胺氧化酶抑制剂帕吉林不仅增加多巴胺的释放，而且增加延迟反应中的错误反应。这个结果很难解释。然而，它提出了一种通过透析探针进行药物注射的新程序。结论：脑透析技术可用于分析认知与神经递质、药物与神经递质之间的关系。

There are several lines of evidence that catecholaminergic neurotransmitters play important roles on the cognitive processes in the monkey prefrontal cortex. In the present study, using the in vivo perfusion dialysis combined with high-performance liquid chromatography (HPLC) with electrochemical detection, we investigated the role of neurotransmitters on spatial short-term memory functions in the rhesus monkey prefrontal cortex. For this purpose, two monkeys were trained on 8-s delayed response task, which is related to spatial short-term memory, and a control, non-delay position discrimination, task. We measured the amount of dopamine and norepinephrine through dialysis probes implanted in the prefrontal cortex. These two tasks are alternated every 20 minutes periods. By comparing the amount of transmitters released while the monkeys are performing these two tasks, we can estimate the role of each transmitter in the prefrontal cortex on spatial short-term memory functions.There were many places where the amount of dopamine release was higher during delayed response performance than during control task performance. These probes were located around the principal sulcus. Lengthening the delay interval resulted in the elevation of dopamine release, which suggests higher activity in the prefrontal cortex in the long delay condition. Pargyline, a MAO-inhibitor, increased not only dopamine release but also error responses in delayed response performance. This result is difficult to interprete. However, it suggests a new procedure of drug injection by dialysis probes. It was difficult for the dialysis procedure to detect laminar differences in neurotransmitter release.In conclusion, the brain dialysis technique is useful for analyses of relations between cognition and neurotransmitters and between drags and neurotransmitters.