Laboratory of Cognitive and Computational Neuroscience, Complutense University of Madrid-Polytechnic University of Madrid, Madrid, Spain.
Neuropsychologia. 2010 Nov;48(13):3846-54. doi: 10.1016/j.neuropsychologia.2010.09.015. Epub 2010 Sep 22.
The present study investigated the binding of verbal and spatial features in immediate memory. In a recent study, we demonstrated incidental and asymmetrical letter-location binding effects when participants attended to letter features (but not when they attended to location features) that were associated with greater oscillatory activity over prefrontal and posterior regions during the retention period. We were interested to investigate whether the patterns of brain activity associated with the incidental binding of letters and locations observed when only the verbal feature is attended differ from those reflecting the binding resulting from the controlled/explicit processing of both verbal and spatial features. To achieve this, neural activity was recorded using magnetoencephalography (MEG) while participants performed two working memory tasks. Both tasks were identical in terms of their perceptual characteristics and only differed with respect to the task instructions. One of the tasks required participants to process both letters and locations. In the other, participants were instructed to memorize only the letters, regardless of their location. Time-frequency representation of MEG data based on the wavelet transform of the signals was calculated on a single trial basis during the maintenance period of both tasks. Critically, despite equivalent behavioural binding effects in both tasks, single and dual feature encoding relied on different neuroanatomical and neural oscillatory correlates. We propose that enhanced activation of an anterior-posterior dorsal network observed in the task requiring the processing of both features reflects the necessity for allocating greater resources to intentionally process verbal and spatial features in this task.
本研究调查了即时记忆中言语和空间特征的结合。在最近的一项研究中，当参与者关注与前额叶和后区域在保留期间的振荡活动相关更大的字母特征（但不关注位置特征时）时，我们证明了偶然的和不对称的字母-位置结合效应。我们有兴趣研究当仅关注言语特征时观察到的与偶然结合的字母和位置相关的大脑活动模式是否与反映由言语和空间特征的控制/显式处理引起的结合不同。为了实现这一目标，使用脑磁图（MEG）记录了神经活动，同时参与者执行了两项工作记忆任务。两个任务在其感知特征方面是相同的，只是在任务指令方面有所不同。其中一项任务要求参与者同时处理字母和位置。在另一项任务中，参与者被指示仅记住字母，而不管其位置如何。在两个任务的维持期间，基于信号的小波变换，对 MEG 数据的时频表示进行了单次试验计算。关键的是，尽管两个任务都存在等效的行为结合效应，但单个和双重特征编码依赖于不同的神经解剖学和神经振荡相关性。我们提出，在需要同时处理两个特征的任务中观察到的前后背侧网络的增强激活反映了在该任务中有意处理言语和空间特征需要分配更多资源的必要性。
