Boussaoud D, Wise S P
Laboratory of Neurophysiology, National Institute of Mental Health, Poolesville, MD 20837.
Exp Brain Res. 1993;95(1):15-27. doi: 10.1007/BF00229650.
We examined neuronal activity in three parts of the primate frontal cortex: the dorsal (PMd) and ventral (PMv) premotor cortex and a ventrolateral part of the dorsolateral prefrontal (PF) cortex. Two monkeys fixated a 0.2 degrees white square in the center of a video display while depressing a switch located between two touch pads. On each trial, a spatial-attentional/mnemonic (SAM) cue was presented first. The SAM cue consisted of one 2 degrees x 2 degrees square, usually red or green, and its location indicated where a conditional motor instruction would appear after a delay period. The stimulus event containing the motor instruction, termed the motor instructional/conditional (MIC) cue, could be of two general types. It might consist of a single 2 degrees x 2 degrees square stimulus identical to one of the SAM cues presented at the same location as the SAM cue on that trial. When the MIC cue was a single square, it instructed the monkey to move its forelimb to one of the two touch pads according to the following conditional rule: a green MIC cue meant that contact with the right touch pad would be rewarded on that trial and a red MIC cue instructed a movement to the left touch pad. Alternatively, the MIC cue might consist of two 2 degrees x 2 degrees squares, only one of which was at the SAM-cue location: in those cases, one square was red and the other was green. The colored square at the SAM cue location for that trial was the instructing stimulus, and the other part of the MIC cue was irrelevant. When, after a variable delay period, the MIC cue disappeared, the monkey had to touch the appropriate target within 1 s to receive a reward and could break visual fixation. The experimental design allowed comparison of frontal cortical activity when one stimulus, identical in retinocentric, craniocentric, and allocentric spatial location as well as all other stimulus parameters, had two different meanings for the animal's behavior. When a stimulus was the SAM cue, it led to either a reorientation of spatial attention to its location, or the storage of its location in spatial memory. By contrast, when it was the MIC cue, the same stimulus instructed a motor act to be executed after a delay period. For the majority of PMd neurons (55%), post-MIC cue activity exceeded post-SAM cue activity.(ABSTRACT TRUNCATED AT 400 WORDS)
背侧（PMd）和腹侧（PMv）运动前皮质以及背外侧前额叶（PF）皮质的腹外侧部分。两只猴子注视着视频显示器中央一个0.2度的白色方块，同时按下位于两个触摸板之间的开关。在每次试验中，首先会呈现一个空间注意/记忆（SAM）线索。SAM线索由一个2度×2度的方块组成，通常为红色或绿色，其位置表明在延迟期后条件性运动指令将会出现的位置。包含运动指令的刺激事件，称为运动指令/条件（MIC）线索，通常有两种类型。它可能由一个与该试验中在与SAM线索相同位置呈现的SAM线索之一相同的2度×2度的单个方块刺激组成。当MIC线索是单个方块时，它指示猴子根据以下条件规则将其前肢移动到两个触摸板之一：绿色的MIC线索意味着在该试验中与右侧触摸板接触将获得奖励，红色的MIC线索指示向左触摸板移动。或者，MIC线索可能由两个2度×2度的方块组成，其中只有一个位于SAM线索的位置：在这些情况下，一个方块是红色的，另一个是绿色的。该试验中位于SAM线索位置的彩色方块是指示性刺激，而MIC线索的另一部分是无关的。在可变的延迟期后，当MIC线索消失时，猴子必须在1秒内触摸适当的目标以获得奖励，并且可以中断视觉注视。该实验设计允许比较当一个在视网膜中心、颅骨中心和异中心空间位置以及所有其他刺激参数上相同的刺激对动物行为有两种不同含义时额叶皮质的活动。当一个刺激是SAM线索时，它会导致空间注意力重新定向到其位置，或者将其位置存储在空间记忆中。相比之下，当它是MIC线索时，相同的刺激指示在延迟期后执行一个运动行为。对于大多数PMd神经元（55%），MIC线索后的活动超过了SAM线索后的活动。（摘要截断于400字）
