Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, North Carolina 27157, USA.
J Neurosci. 2012 May 2;32(18):6161-9. doi: 10.1523/JNEUROSCI.6365-11.2012.
The lateral prefrontal cortex plays an important role in working memory and decision-making, although little is known about how neural correlates of these functions are shaped by learning. To understand the effect of learning on the neuronal representation of decision-making, we recorded single neurons from the lateral prefrontal cortex of monkeys before and after they were trained to judge whether two stimuli appeared at matching spatial locations. After training, and in agreement with previous studies, a population of neurons exhibited activity that was modulated depending on whether the second stimulus constituted a match or not, which had predictive ability for the monkey's choice. However, even before training, prefrontal neurons displayed modulation depending on the match or non-match status of a stimulus, with approximately equal percentages of neurons preferring a match or a non-match. The difference in firing rate and discriminability for match and non-match stimuli before training was of comparable magnitude as that after training. Changes observed after training involved an increase in the percentage of neurons exhibiting this effect, a greater proportion of neurons preferring non-match stimuli, and a greater percentage of neurons representing information about the first stimulus during the presentation of the second stimulus. Our results suggest that the neuronal activity representing some match/non-match judgments is present in the lateral prefrontal cortex even when subjects are not required to perform a comparison and before any training.
外侧前额叶皮层在工作记忆和决策中发挥着重要作用，尽管人们对这些功能的神经相关性如何通过学习来塑造知之甚少。为了了解学习对决策神经元表示的影响，我们在猴子接受训练以判断两个刺激是否出现在匹配的空间位置之前和之后，从其外侧前额叶皮层中记录了单个神经元。经过训练后，与之前的研究一致，一群神经元表现出的活动取决于第二个刺激是否匹配，而这对猴子的选择具有预测能力。然而，即使在训练之前，前额叶神经元也表现出对刺激的匹配或不匹配状态的调制，其中大约有相等比例的神经元更喜欢匹配或不匹配。在训练之前，匹配和不匹配刺激的放电率和可辨别性的差异与训练后相当。训练后观察到的变化涉及表现出这种效应的神经元百分比增加、更喜欢不匹配刺激的神经元比例增加以及在呈现第二个刺激时代表第一个刺激信息的神经元百分比增加。我们的结果表明，即使在不需要进行比较并且在没有任何训练的情况下，代表某些匹配/不匹配判断的神经元活动也存在于外侧前额叶皮层中。
