Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, North Carolina.
Department of Neurobiology and Anatomy, Wake Forest University School of Medicine, Winston-Salem, North Carolina
J Neurophysiol. 2015 Jan 1;113(1):44-57. doi: 10.1152/jn.00413.2014. Epub 2014 Oct 8.
Both dorsolateral prefrontal and posterior parietal cortex have been implicated in spatial working memory and representation of task information. Prior experiments training animals to recall the first of a sequence of stimuli and examining the effect of subsequent distractors have identified increased ability of the prefrontal cortex to represent remembered stimuli and filter distractors. It is unclear, however, if this prefrontal functional specialization extends to stimuli appearing earlier in a sequence, when subjects are cued to remember subsequent ones. It is also not known how task information interacts with persistent activity representing remembered stimuli and distractors in the two areas. To address these questions, we trained monkeys to remember either the first or second of two stimuli presented in sequence and recorded neuronal activity from the posterior parietal and dorsolateral prefrontal cortex. The prefrontal cortex was better able to represent the actively remembered stimulus, whereas the posterior parietal cortex was more modulated by distractors; however, task effects interfered with this representation. As a result, large proportions of neurons with persistent activity and task effects exhibited a preference for a stimulus when it appeared as a distractor in both areas. Additionally, prefrontal neurons were modulated to a greater extent by task factors during the delay period of the task. The results indicate that the prefrontal cortex is better able than the posterior parietal cortex to differentiate between distractors and actively remembered stimuli and is more modulated by the task; however, this relative preference is highly context dependent and depends on the specific requirements of the task.
背外侧前额叶皮层和顶后皮质都与空间工作记忆和任务信息的表示有关。先前的实验训练动物回忆序列中第一个刺激，并检查后续干扰物的影响，结果表明前额叶皮层有更强的能力来表示记忆中的刺激并过滤干扰物。然而，目前尚不清楚这种前额叶功能特化是否扩展到序列中较早出现的刺激，当被试被提示记住后续刺激时。也不知道任务信息如何与两个区域中表示记忆刺激和干扰物的持续活动相互作用。为了解决这些问题，我们训练猴子记住序列中呈现的两个刺激中的第一个或第二个，并记录来自顶后皮质和背外侧前额叶皮层的神经元活动。前额叶皮层能够更好地表示主动记忆的刺激，而顶后皮质则更多地受到干扰物的调节；然而，任务效应干扰了这种表示。结果，大量具有持续活动和任务效应的神经元在两个区域中作为干扰物出现时，对刺激表现出偏好。此外，在任务的延迟期间，前额叶神经元受任务因素的调节程度更大。结果表明，前额叶皮层比顶后皮质更能区分干扰物和主动记忆的刺激，并且更容易受到任务的调节；然而，这种相对偏好高度依赖于上下文，取决于任务的具体要求。
