在延缓分辨作业的学习过程中猕猴大脑皮层慢电位的变化

INVESTIGATION OF CORTICAL SLOW POTENTIALS DURDOG THE DELAYED DISCRIMINATION LEARNING IN MONKEYS

本工作在两只猕猴上记录了在延缓分辨作业不同训练阶段的皮层慢电位变化。分辨作业模型与前文报道的相同。延缓分辨行为建立后,在额区的许多部位都能记录到负的慢电位变化。这种慢电位变化出现在延缓期,其幅度随动物行为正确率的提高而增大。这种慢电位在前额区具有最大幅度,在中央沟以后的区域则未能记录到。负慢电位在左右两侧半球的分布基本对称,其幅度大小亦无显著差别。在延缓分辨行为反应消退后,负慢电位也随之消失。在延缓分辨作业的两种测试模式,即给于电击的 R 模式及不给予电击的 B 模式上,负慢电位均出现在延缓期,在时程和幅度上未表现出模式特异性。以上结果提示,本实验中记录到的负慢电位是依赖于学习过程的。它反映了事件间条件性联系的建立。这一负慢电位在前额皮层具有最大的幅值,并出现在延缓期的实验结果支持了前额皮层在短时记忆过程中起着重要作用的论点。

Averaged slow potentials(SPs)were recorded at different training stages ofdelayed discrimination learning in two monkeys.The details of the task sequencewas described in our previous work.It was found that at the early stages of the training the amplitude of SPs wasvery small,and it increased gradually with the increase of percentage of correctresponses.The SPs recorded from the prefrontal cortex had the largest amplitudeand there was no SPs recorded from the rear portion of the cortex.SPs recordedfrom the symmetrical sites of the two hemispheres showed no significant differencesin amplitude and duration.Moreover,the SPs did not show significant differencesin amplitude and distribution between two test models(R Model and B Model).The results obtained from the extinction experiments showed that after extinctionof the behavioral responses the SPs disappeared.The results showed that the SPs recorded were learning-dependent and re-presented the association of events.As the SPs appeared in the delay period andwere prefrontal-dominant,it was suggested that the prefrontal cortex might playan important role in short-term memory process.