Johnson Jennifer Adrienne, Zatorre Robert J
Montreal Neurological Institute, McGill University, 3801 University St., Montreal, QC H3A 2B4, Canada.
Neuroimage. 2006 Jul 15;31(4):1673-81. doi: 10.1016/j.neuroimage.2006.02.026. Epub 2006 Apr 17.
With information constantly bombarding the human sensory systems, how is it that we attend to behaviorally relevant information? The present study examined the behavioral and neural bases of attending to one sense while ignoring another sense (bimodal selective attention) contrasted with attending simultaneously to two senses (bimodal divided attention). In a functional magnetic resonance imaging (fMRI) study, subjects simultaneously heard novel melodies and viewed geometric shapes. They were instructed to actively attend to only one or to both senses (selective or divided attention) or as a baseline condition, passively observe both (bimodal passive). Memory tests for both attended and unattended stimuli validated that subjects were following the attention instructions. Selective attention led to increased activity in relevant sensory cortices while simultaneously leading to decreased activity in irrelevant sensory cortices. The divided attention instruction did not lead to a global increase in sensory cortex activity compared to the bimodal passive baseline condition. However, divided attention did recruit heteromodal areas in the left dorsolateral prefrontal cortex, while selective attention did not recruit any frontal areas. We propose that sustained selective and divided bimodal attention were achieved via distinct neural processes. Selective attention was achieved primarily via modulation of the sensory cortices. Divided attention was achieved for most individuals via recruitment of the middle-dorsolateral prefrontal cortex. However, there was also a trade-off between activity in posterior-dorsolateral prefrontal cortex and sensory regions, such that individuals who demonstrated the best performance during divided attention also showed the greatest recruitment of sensory cortices.
在信息不断冲击人类感官系统的情况下，我们是如何关注与行为相关的信息的呢？本研究考察了专注于一种感官而忽略另一种感官（双峰选择性注意）与同时关注两种感官（双峰分散性注意）的行为和神经基础，并进行了对比。在一项功能磁共振成像（fMRI）研究中，受试者同时听新颖的旋律并观看几何形状。他们被指示仅积极关注一种感官或两种感官（选择性或分散性注意），或者作为基线条件，被动观察两者（双峰被动）。对关注和未关注刺激的记忆测试证实受试者遵循了注意指示。选择性注意导致相关感觉皮层的活动增加，同时导致不相关感觉皮层的活动减少。与双峰被动基线条件相比，分散性注意指令并未导致感觉皮层活动的整体增加。然而，分散性注意确实激活了左背外侧前额叶皮层的异模态区域，而选择性注意未激活任何额叶区域。我们提出，持续的选择性和分散性双峰注意是通过不同的神经过程实现的。选择性注意主要通过感觉皮层的调制来实现。对于大多数个体来说，分散性注意是通过募集背外侧前额叶中部皮层来实现的。然而，背外侧前额叶后部皮层和感觉区域的活动之间也存在权衡，即在分散性注意期间表现最佳的个体也表现出感觉皮层的最大募集。
