Pasternak Tatiana, Lui Leo L, Spinelli Philip M
Department of Neurobiology and Anatomy, and Center for Visual Science, University of Rochester, Rochester, New York 14642
Department of Neurobiology and Anatomy, and Center for Visual Science, University of Rochester, Rochester, New York 14642.
J Neurosci. 2015 May 6;35(18):7095-105. doi: 10.1523/JNEUROSCI.5265-14.2015.
The contribution of the lateral prefrontal cortex (LPFC) to working memory is the topic of active debate. On the one hand, it has been argued that the persistent delay activity in LPFC recorded during some working memory tasks is a reflection of sensory storage, the notion supported by some lesion studies. On the other hand, there is emerging evidence that the LPFC plays a key role in the maintenance of sensory information not by storing relevant visual signals but by allocating visual attention to such stimuli. In this study, we addressed this question by examining the effects of unilateral LPFC lesions during a working memory task requiring monkeys to compare directions of two moving stimuli, separated by a delay. The lesions resulted in impaired thresholds for contralesional stimuli at longer delays, and these deficits were most dramatic when the task required rapid reallocation of spatial attention. In addition, these effects were equally pronounced when the remembered stimuli were at threshold or moved coherently. The contralesional nature of the deficits points to the importance of the interactions between the LPFC and the motion processing neurons residing in extrastriate area MT. Delay-specificity of the deficit supports LPFC involvement in the maintenance stage of the comparison task. However, because this deficit was independent of stimulus features giving rise to the remembered direction and was most pronounced during rapid shifts of attention, its role is more likely to be attending and accessing the preserved motion signals rather than their storage.
外侧前额叶皮质（LPFC）对工作记忆的贡献是一个活跃的争论话题。一方面，有人认为在某些工作记忆任务中记录到的LPFC持续延迟活动是感觉存储的反映，一些损伤研究支持了这一观点。另一方面，有新证据表明，LPFC在感觉信息的维持中起关键作用，不是通过存储相关视觉信号，而是通过将视觉注意力分配到此类刺激上。在本研究中，我们通过在一项工作记忆任务中检查单侧LPFC损伤的影响来解决这个问题，该任务要求猴子比较两个移动刺激的方向，中间有延迟。损伤导致在较长延迟时对侧刺激的阈值受损，当任务需要快速重新分配空间注意力时，这些缺陷最为明显。此外，当记忆的刺激处于阈值或连贯移动时，这些影响同样显著。缺陷的对侧性质表明LPFC与位于纹外区MT的运动处理神经元之间相互作用的重要性。缺陷的延迟特异性支持LPFC参与比较任务的维持阶段。然而，由于这种缺陷与产生记忆方向的刺激特征无关，并且在注意力快速转移期间最为明显，其作用更可能是关注和获取保留的运动信号，而不是存储它们。
