Department of Neurobiology and Anatomy, University of Rochester, Rochester, New York 14642, USA.
J Neurosci. 2013 Jan 16;33(3):972-86. doi: 10.1523/JNEUROSCI.4075-12.2013.
When a monkey needs to decide whether motion direction of one stimulus is the same or different as that of another held in working memory, neurons in dorsolateral prefrontal cortex (DLPFC) faithfully represent the motion directions being evaluated and contribute to their comparison. Here, we examined whether DLPFC neurons are more generally involved in other types of sensory comparisons. Such involvement would support the existence of generalized sensory comparison mechanisms within DLPFC, shedding light on top-down influences this region is likely to provide to the upstream sensory neurons during comparison tasks. We recorded activity of individual neurons in the DLPFC while monkeys performed a memory-guided decision task in which the important dimension was the speed of two sequentially presented moving random-dot stimuli. We found that many neurons, both narrow-spiking putative local interneurons and broad-spiking putative pyramidal output cells, were speed-selective, with tuning reminiscent of that observed in the motion processing middle temporal (MT) cortical area. Throughout the delay, broad-spiking neurons were more active, showing anticipatory rate modulation and transient periods of speed selectivity. During the comparison stimulus, responses of both cell types were modulated by the speed of the first stimulus, and their activity was highly predictive of the animals' behavioral report. These results are similar to those found for comparisons of motion direction, suggesting the existence of generalized neural mechanisms in the DLPFC subserving the comparison of sensory signals.
当猴子需要决定一个刺激的运动方向与工作记忆中另一个刺激的运动方向是否相同时，背外侧前额叶皮层（DLPFC）中的神经元忠实地表示正在评估的运动方向，并有助于它们的比较。在这里，我们研究了 DLPFC 神经元是否更普遍地参与其他类型的感官比较。这种参与将支持 DLPFC 中存在通用的感官比较机制，为该区域在比较任务期间可能向上游感觉神经元提供的自上而下的影响提供了线索。当猴子执行一项记忆引导的决策任务时，我们记录了 DLPFC 中单个神经元的活动，在该任务中，重要的维度是两个连续呈现的运动随机点刺激的速度。我们发现，许多神经元，无论是窄峰假定局部中间神经元还是宽峰假定金字塔输出细胞，都是速度选择性的，其调谐类似于在运动处理中颞叶（MT）皮质区域观察到的调谐。在整个延迟期间，宽峰神经元更活跃，表现出预期的速率调制和短暂的速度选择性。在比较刺激期间，两种细胞类型的反应都受到第一个刺激速度的调制，它们的活动高度预测了动物的行为报告。这些结果与运动方向比较的结果相似，表明 DLPFC 中存在通用的神经机制，用于比较感觉信号。
