猕猴前额皮层神经元对信号刺激和无关刺激反应的比较研究

在两只已建立视觉分辨行为以及一只未经训练的猕猴上记录了前额皮层主沟区的单位放电，视觉分辨作业包括下列事件；（1）暗示信号红光（在R模式中）或蓝光（在B模式中）（1.30^s);(2）延缓期（2.10s)；（3）反应期出现白光（1.88s)在R模式中动物必需在白光出现后立即拉杆以避免电击在B模式中不给予电击,要求动物不拉杆,共记录了127个前额皮层单位,其中80个单位的放电变化与视觉分辨作业的事件相关,占总数的63%,在测试间歇期内观察了前额皮尾神经元对无关的短声\闪光以及闪烁的红、蓝和白光的反应，总共对96个单位进行了短声和/或闪光刺激的测试，其中23个（24%）对上述刺激产生反应，并大部分（15个）是与行为作业中事件相关的单位，在对103个单位进行闪烁的红、蓝、白光测试中，发现只有12个（12%）单位有反应，在另一只未经训练的猕猴的前额皮层主沟区记录了100个单位，发现只有4个（4%）单位对无关的光刺激有反应，这些光刺激的物理性与上述实验中所采用的刺激相同，以上结果表明，通过学习具有行为意义的刺激能引起更多的前额叶神经元的放电活动，也就是说前额叶神经元对具有行为意义的刺激的反应是在学习过程中形成的，它们的活动是可塑的。

COMPARISON BETWEEN RESPONSES OF MONKEY PREFRONTAL NEURONS TO SIGNAL AND TNDIFFERENT STIMULI

Unit activities of the principal sulcus area were recorded in three monkeys(Macaca mullata).Two of them were trained to perform visual discrimination task,and the other had not received any training.The sequence of the task is as follows:(1)a cue of presentation of red(in R Model)or blue(in B Model)light(1.3s);(2)a delay period(2.1s);(3)a reaction period of presentation of white light(4.88s).The monkey should draw a bar after the onset of the white light of R Model toavoid a electric shock,and should not draw the bar after the onset of the white lightof B Model in which the monkeys would not receive the electric shock.Of 127 prefrontal units recorded from the two trained monkeys when they wereperforming the task,80 units(63%)were related to the events of the task.Ninety sixunits were recorded for the test of responses to click and flash in the intertrial interval,and 23 units(24%)responsed to click and/or flash.Fifteen out of 23 units were event-related.Twelve out of 103 units responsed to the red,blue and white flash in theintertrial interval.A hundred units were recorded from the untrained monkey aonly 4 units showed nonspecific responses to the indifferent stimuli.The results showed that after training much more prefrontal neurons involvedin processing of the information of signal stimuli than those in response to the indif-ferent stimuli.In other words,the prefrontal neurons possess plasticity and changetheir activities during the training of visual discrimination task.