Institute of Cognitive Neuroscience - UCL (University College London), 17 Queen Square, London WC1N 3AR, UK.
Neuropsychologia. 2011 Jul;49(8):2185-98. doi: 10.1016/j.neuropsychologia.2011.02.045. Epub 2011 Mar 1.
Patients with lesions in rostral prefrontal cortex (PFC) often experience problems in everyday-life situations requiring multitasking. A key cognitive component that is critical in multitasking situations is prospective memory, defined as the ability to carry out an intended action after a delay period filled with unrelated activity. The few functional imaging studies investigating prospective memory have shown consistent activation in both medial and lateral rostral PFC but also in more posterior prefrontal regions and non-frontal regions. The aim of this study was to determine regions that are necessary for prospective memory performance, using the human lesion approach. We designed an experimental paradigm allowing us to assess time-based (remembering to do something at a particular time) and event-based (remembering to do something in a particular situation) prospective memory, using two types of material, words and pictures. Time estimation tasks and tasks controlling for basic attention, inhibition and multiple instructions processing were also administered. We examined brain-behaviour relationships with a voxelwise lesion method in 45 patients with focal brain lesions and 107 control subjects using this paradigm. The results showed that lesions in the right polar prefrontal region (in Brodmann area 10) were specifically associated with a deficit in time-based prospective memory tasks for both words and pictures. This deficit could not be explained by impairments in basic attention, detection, inhibition or multiple instruction processing, and there was also no deficit in event-based prospective memory conditions. In addition to their prospective memory difficulties, these polar prefrontal patients were significantly impaired in time estimation ability compared to other patients. The same region was found to be involved using both words and pictures, suggesting that right rostral PFC plays a material nonspecific role in prospective memory. This is the first lesion study showing that rostral PFC is crucial for time-based prospective memory. The findings suggest that time-based and event-based prospective memory might be supported at least in part by distinct brain regions. Two particularly plausible explanations for the deficit rest upon a possible role for polar prefrontal structures in supporting in time estimation, and/or in retrieving an intention to act. More broadly, the results are consistent with the view that the deficit of rostral patients in multitasking situations might at least in part be explained by a deficit in prospective memory.
前额皮质（PFC）损伤的患者在日常生活中经常遇到需要多任务处理的问题。多任务处理情境下的关键认知成分是前瞻性记忆，即延迟一段时间后仍能执行预先计划的行为的能力。少数功能影像学研究表明，内侧和外侧额前皮质以及更靠后的前额皮质和非前额皮质区域都与前瞻性记忆有关。本研究旨在采用人类脑损伤方法确定进行前瞻性记忆所需的脑区。我们设计了一个实验范式，允许我们使用两种材料（单词和图片）评估基于时间（在特定时间记住要做某事）和基于事件（在特定情况下记住要做某事）的前瞻性记忆。我们还进行了时间估计任务以及控制基本注意、抑制和多重指令处理的任务。我们使用该范式，对 45 名患有局灶性脑损伤的患者和 107 名对照者进行了基于体素的脑损伤方法，以检查大脑与行为之间的关系。结果表明，右侧极额前皮质（Brodmann 区 10）的损伤与基于时间的单词和图片前瞻性记忆任务缺陷有关。这种缺陷不能用基本注意、检测、抑制或多重指令处理的损伤来解释，基于事件的前瞻性记忆条件也没有缺陷。除了前瞻性记忆困难外，这些极额前皮质患者在时间估计能力方面明显受损，与其他患者相比。与其他患者相比，使用单词和图片均发现同一区域受损，表明右侧额前皮质在前瞻性记忆中发挥了材料非特异性作用。这是第一个表明额前皮质对基于时间的前瞻性记忆至关重要的脑损伤研究。这些发现表明，基于时间的和基于事件的前瞻性记忆可能至少部分由不同的脑区支持。对于这种缺陷，有两种特别合理的解释，一种可能是极额前皮质结构在支持时间估计方面发挥作用，另一种可能是在检索执行意图方面发挥作用。更广泛地说，这些结果与以下观点一致，即前额皮质损伤患者在多任务处理情境下的缺陷至少部分可以用前瞻性记忆缺陷来解释。
